A Database object represents a virtual connection to a database. The Database class is meant to be subclassed by database adapters in order to provide the functionality needed for executing queries.
This methods generally execute SQL code on the database server.
Runs the supplied SQL statement string on the database server. Returns self so it can be safely chained:
DB << "UPDATE albums SET artist_id = NULL" << "DROP TABLE artists"
# File lib/sequel/database/query.rb, line 25 def <<(sql) run(sql) self end
Call the prepared statement with the given name with the given hash of arguments.
DB[:items].filter(:id=>1).prepare(:first, :sa) DB.call(:sa) # SELECT * FROM items WHERE id = 1
# File lib/sequel/database/query.rb, line 35 def call(ps_name, hash={}, &block) prepared_statement(ps_name).call(hash, &block) end
Dump foreign key constraints for all tables as a migration. This complements the :foreign_keys=>false option to dump_schema_migration. This only dumps the constraints (not the columns) using alter_table/add_foreign_key with an array of columns.
Note that the migration this produces does not have a down block, so you cannot reverse it.
# File lib/sequel/extensions/schema_dumper.rb, line 25 def dump_foreign_key_migration(options={}) Sequel::Deprecation.deprecate('Loading the schema_dumper extension globally', "Please use Database#extension to load the extension into this database") unless is_a?(SchemaDumper) ts = tables(options) Sequel.migration do change do#{ts.sort_by{|t| t.to_s}.map{|t| dump_table_foreign_keys(t)}.reject{|x| x == ''}.join("\n\n").gsub(/^/o, ' ')} endend end
Dump indexes for all tables as a migration. This complements the :indexes=>false option to dump_schema_migration. Options:
:same_db |
Create a dump for the same database type, so don't ignore errors if the index statements fail. |
:index_names |
If set to false, don't record names of indexes. If set to :namespace, prepend the table name to the index name if the database does not use a global index namespace. |
# File lib/sequel/extensions/schema_dumper.rb, line 44 def dump_indexes_migration(options={}) Sequel::Deprecation.deprecate('Loading the schema_dumper extension globally', "Please use Database#extension to load the extension into this database") unless is_a?(SchemaDumper) ts = tables(options) Sequel.migration do change do#{ts.sort_by{|t| t.to_s}.map{|t| dump_table_indexes(t, :add_index, options)}.reject{|x| x == ''}.join("\n\n").gsub(/^/o, ' ')} endend end
Dump the cached schema to the filename given in Marshal format.
# File lib/sequel/extensions/schema_caching.rb, line 51 def dump_schema_cache(file) Sequel::Deprecation.deprecate('Loading the schema_caching extension globally', "Please use Database#extension to load the extension into this database") unless is_a?(SchemaCaching) File.open(file, 'wb'){|f| f.write(Marshal.dump(@schemas))} nil end
Dump the cached schema to the filename given unless the file already exists.
# File lib/sequel/extensions/schema_caching.rb, line 59 def dump_schema_cache?(file) Sequel::Deprecation.deprecate('Loading the schema_caching extension globally', "Please use Database#extension to load the extension into this database") unless is_a?(SchemaCaching) dump_schema_cache(file) unless File.exist?(file) end
Return a string that contains a Sequel::Migration subclass that when run would recreate the database structure. Options:
:same_db |
Don't attempt to translate database types to ruby types. If this isn't set to true, all database types will be translated to ruby types, but there is no guarantee that the migration generated will yield the same type. Without this set, types that aren't recognized will be translated to a string-like type. |
:foreign_keys |
If set to false, don't dump foreign_keys (they can be |
added later via #dump_foreign_key_migration)
:indexes |
If set to false, don't dump indexes (they can be added later via dump_index_migration). |
:index_names |
If set to false, don't record names of indexes. If set to :namespace, prepend the table name to the index name. |
# File lib/sequel/extensions/schema_dumper.rb, line 69 def dump_schema_migration(options={}) Sequel::Deprecation.deprecate('Loading the schema_dumper extension globally', "Please use Database#extension to load the extension into this database") unless is_a?(SchemaDumper) options = options.dup if options[:indexes] == false && !options.has_key?(:foreign_keys) # Unless foreign_keys option is specifically set, disable if indexes # are disabled, as foreign keys that point to non-primary keys rely # on unique indexes being created first options[:foreign_keys] = false end ts = sort_dumped_tables(tables(options), options) skipped_fks = if sfk = options[:skipped_foreign_keys] # Handle skipped foreign keys by adding them at the end via # alter_table/add_foreign_key. Note that skipped foreign keys # probably result in a broken down migration. sfka = sfk.sort_by{|table, fks| table.to_s}.map{|table, fks| dump_add_fk_constraints(table, fks.values)} sfka.join("\n\n").gsub(/^/, ' ') unless sfka.empty? end Sequel.migration do change do#{ts.map{|t| dump_table_schema(t, options)}.join("\n\n").gsub(/^/o, ' ')}#{"\n \n" if skipped_fks}#{skipped_fks} endend end
Return a string with a create table block that will recreate the given table's schema. Takes the same options as dump_schema_migration.
# File lib/sequel/extensions/schema_dumper.rb, line 99 def dump_table_schema(table, options={}) Sequel::Deprecation.deprecate('Loading the schema_dumper extension globally', "Please use Database#extension to load the extension into this database") unless is_a?(SchemaDumper) table = table.value.to_s if table.is_a?(SQL::Identifier) gen = dump_table_generator(table, options) commands = [gen.dump_columns, gen.dump_constraints, gen.dump_indexes].reject{|x| x == ''}.join("\n\n") "create_table(#{table.inspect}#{', :ignore_index_errors=>true' if !options[:same_db] && options[:indexes] != false && !gen.indexes.empty?}) do\n#{commands.gsub(/^/o, ' ')}\nend" end
Executes the given SQL on the database. This method should be overridden in descendants. This method should not be called directly by user code.
# File lib/sequel/database/query.rb, line 41 def execute(sql, opts={}) Sequel::Deprecation.deprecate('Database#execute default implementation and Sequel::NotImplemented', 'All database instances can be assumed to implement execute') raise NotImplemented, "#execute should be overridden by adapters" end
Method that should be used when submitting any DDL (Data Definition Language) SQL, such as create_table. By default, calls execute_dui. This method should not be called directly by user code.
# File lib/sequel/database/query.rb, line 49 def execute_ddl(sql, opts={}, &block) execute_dui(sql, opts, &block) end
Method that should be used when issuing a DELETE, UPDATE, or INSERT statement. By default, calls execute. This method should not be called directly by user code.
# File lib/sequel/database/query.rb, line 56 def execute_dui(sql, opts={}, &block) execute(sql, opts, &block) end
Method that should be used when issuing a INSERT statement. By default, calls execute_dui. This method should not be called directly by user code.
# File lib/sequel/database/query.rb, line 63 def execute_insert(sql, opts={}, &block) execute_dui(sql, opts, &block) end
Returns an array of hashes containing foreign key information from the table. Each hash will contain at least the following fields:
:columns |
An array of columns in the given table |
:table |
The table referenced by the columns |
:key |
An array of columns referenced (in the table specified by :table), but can be nil on certain adapters if the primary key is referenced. |
The hash may also contain entries for:
:deferrable |
Whether the constraint is deferrable |
:name |
The name of the constraint |
:on_delete |
The action to take ON DELETE |
:on_update |
The action to take ON UPDATE |
# File lib/sequel/database/query.rb, line 81 def foreign_key_list(table, opts={}) Sequel::Deprecation.deprecate('Database#foreign_key_list default implementation and Sequel::NotImplemented', 'Use Database#supports_foreign_key_parsing? to check for support') raise NotImplemented, "#foreign_key_list should be overridden by adapters" end
Returns a single value from the database, e.g.:
DB.get(1) # SELECT 1 # => 1 DB.get{server_version{}} # SELECT server_version()
# File lib/sequel/database/query.rb, line 91 def get(*args, &block) @default_dataset.get(*args, &block) end
Return a hash containing index information for the table. Hash keys are index name symbols. Values are subhashes with two keys, :columns and :unique. The value of :columns is an array of symbols of column names. The value of :unique is true or false depending on if the index is unique.
Should not include the primary key index, functional indexes, or partial indexes.
DB.indexes(:artists) # => {:artists_name_ukey=>{:columns=>[:name], :unique=>true}}
# File lib/sequel/database/query.rb, line 104 def indexes(table, opts={}) Sequel::Deprecation.deprecate('Database#indexes default implementation and Sequel::NotImplemented', 'Use Database#supports_index_parsing? to check for support') raise NotImplemented, "#indexes should be overridden by adapters" end
Replace the schema cache with the data from the given file, which should be in Marshal format.
# File lib/sequel/extensions/schema_caching.rb, line 66 def load_schema_cache(file) Sequel::Deprecation.deprecate('Loading the schema_caching extension globally', "Please use Database#extension to load the extension into this database") unless is_a?(SchemaCaching) @schemas = Marshal.load(File.read(file)) nil end
Replace the schema cache with the data from the given file if the file exists.
# File lib/sequel/extensions/schema_caching.rb, line 74 def load_schema_cache?(file) Sequel::Deprecation.deprecate('Loading the schema_caching extension globally', "Please use Database#extension to load the extension into this database") unless is_a?(SchemaCaching) load_schema_cache(file) if File.exist?(file) end
Return a dataset modified by the query block
# File lib/sequel/extensions/query.rb, line 24 def query(&block) Sequel::Deprecation.deprecate('Loading the query extension globally', "Please use Database#extension to load the extension into this database") unless is_a?(DatabaseQuery) dataset.query(&block) end
Returns the schema for the given table as an array with all members being arrays of length 2, the first member being the column name, and the second member being a hash of column information. The table argument can also be a dataset, as long as it only has one table. Available options are:
:reload |
Ignore any cached results, and get fresh information from the database. |
:schema |
An explicit schema to use. It may also be implicitly provided via the table name. |
If schema parsing is supported by the database, the column information should hash at least contain the following entries:
:allow_null |
Whether NULL is an allowed value for the column. |
:db_type |
The database type for the column, as a database specific string. |
:default |
The database default for the column, as a database specific string. |
:primary_key |
Whether the columns is a primary key column. If this column is not present, it means that primary key information is unavailable, not that the column is not a primary key. |
:ruby_default |
The database default for the column, as a ruby object. In many cases, complex database defaults cannot be parsed into ruby objects, in which case nil will be used as the value. |
:type |
A symbol specifying the type, such as :integer or :string. |
Example:
DB.schema(:artists) # [[:id, # {:type=>:integer, # :primary_key=>true, # :default=>"nextval('artist_id_seq'::regclass)", # :ruby_default=>nil, # :db_type=>"integer", # :allow_null=>false}], # [:name, # {:type=>:string, # :primary_key=>false, # :default=>nil, # :ruby_default=>nil, # :db_type=>"text", # :allow_null=>false}]]
# File lib/sequel/database/query.rb, line 159 def schema(table, opts={}) raise(Error, 'schema parsing is not implemented on this database') unless supports_schema_parsing? opts = opts.dup tab = if table.is_a?(Dataset) o = table.opts from = o[:from] raise(Error, "can only parse the schema for a dataset with a single from table") unless from && from.length == 1 && !o.include?(:join) && !o.include?(:sql) table.first_source_table else table end qualifiers = split_qualifiers(tab) table_name = qualifiers.pop sch = qualifiers.pop information_schema_schema = case qualifiers.length when 1 Sequel.identifier(*qualifiers) when 2 Sequel.qualify(*qualifiers) end if table.is_a?(Dataset) quoted_name = table.literal(tab) opts[:dataset] = table else quoted_name = schema_utility_dataset.literal(table) end opts[:schema] = sch if sch && !opts.include?(:schema) opts[:information_schema_schema] = information_schema_schema if information_schema_schema && !opts.include?(:information_schema_schema) Sequel.synchronize{@schemas.delete(quoted_name)} if opts[:reload] if v = Sequel.synchronize{@schemas[quoted_name]} return v end cols = schema_parse_table(table_name, opts) raise(Error, 'schema parsing returned no columns, table probably doesn\t exist') if cols.nil? || cols.empty? cols.each{|_,c| c[:ruby_default] = column_schema_to_ruby_default(c[:default], c[:type])} Sequel.synchronize{@schemas[quoted_name] = cols} if cache_schema cols end
Returns true if a table with the given name exists. This requires a query to the database.
DB.table_exists?(:foo) # => false # SELECT NULL FROM foo LIMIT 1
Note that since this does a SELECT from the table, it can give false negatives if you don't have permission to SELECT from the table.
# File lib/sequel/database/query.rb, line 212 def table_exists?(name) sch, table_name = schema_and_table(name) name = SQL::QualifiedIdentifier.new(sch, table_name) if sch _table_exists?(from(name)) true rescue DatabaseError false end
Return all tables in the database as an array of symbols.
DB.tables # => [:albums, :artists]
# File lib/sequel/database/query.rb, line 224 def tables(opts={}) Sequel::Deprecation.deprecate('Database#tables default implementation and Sequel::NotImplemented', 'Use Database#supports_table_listing? to check for support') raise NotImplemented, "#tables should be overridden by adapters" end
Return all views in the database as an array of symbols.
DB.views # => [:gold_albums, :artists_with_many_albums]
# File lib/sequel/database/query.rb, line 232 def views(opts={}) Sequel::Deprecation.deprecate('Database#views default implementation and Sequel::NotImplemented', 'Use Database#supports_view_listing? to check for support') raise NotImplemented, "#views should be overridden by adapters" end
These methods execute code on the database that modifies the database's schema.
The order of column modifiers to use when defining a column.
The alter table operations that are combinable.
The default options for join table columns.
Adds a column to the specified table. This method expects a column name, a datatype and optionally a hash with additional constraints and options:
DB.add_column :items, :name, :text, :unique => true, :null => false DB.add_column :items, :category, :text, :default => 'ruby'
See alter_table.
# File lib/sequel/database/schema_methods.rb, line 36 def add_column(table, *args) alter_table(table) {add_column(*args)} end
Adds an index to a table for the given columns:
DB.add_index :posts, :title DB.add_index :posts, [:author, :title], :unique => true
Options:
:ignore_errors |
Ignore any DatabaseErrors that are raised |
See alter_table.
# File lib/sequel/database/schema_methods.rb, line 49 def add_index(table, columns, options={}) e = options[:ignore_errors] begin alter_table(table){add_index(columns, options)} rescue DatabaseError raise unless e end end
Alters the given table with the specified block. Example:
DB.alter_table :items do add_column :category, :text, :default => 'ruby' drop_column :category rename_column :cntr, :counter set_column_type :value, :float set_column_default :value, :float add_index [:group, :category] drop_index [:group, :category] end
Note that add_column accepts all the options available for column definitions using create_table, and add_index accepts all the options available for index definition.
See Schema::AlterTableGenerator and the "Migrations and Schema Modification" guide.
# File lib/sequel/database/schema_methods.rb, line 75 def alter_table(name, generator=nil, &block) generator ||= alter_table_generator(&block) remove_cached_schema(name) apply_alter_table_generator(name, generator) nil end
Return a new Schema::AlterTableGenerator instance with the receiver as the database and the given block.
# File lib/sequel/database/schema_methods.rb, line 84 def alter_table_generator(&block) alter_table_generator_class.new(self, &block) end
Create a join table using a hash of foreign keys to referenced table names. Example:
create_join_table(:cat_id=>:cats, :dog_id=>:dogs) # CREATE TABLE cats_dogs ( # cat_id integer NOT NULL REFERENCES cats, # dog_id integer NOT NULL REFERENCES dogs, # PRIMARY KEY (cat_id, dog_id) # ) # CREATE INDEX cats_dogs_dog_id_cat_id_index ON cats_dogs(dog_id, cat_id)
The primary key and index are used so that almost all operations on the table can benefit from one of the two indexes, and the primary key ensures that entries in the table are unique, which is the typical desire for a join table.
You can provide column options by making the values in the hash be option hashes, so long as the option hashes have a :table entry giving the table referenced:
create_join_table(:cat_id=>{:table=>:cats, :type=>Bignum}, :dog_id=>:dogs)
You can provide a second argument which is a table options hash:
create_join_table({:cat_id=>:cats, :dog_id=>:dogs}, :temp=>true)
Some table options are handled specially:
:index_options |
The options to pass to the index |
:name |
The name of the table to create |
:no_index |
Set to true not to create the second index. |
:no_primary_key |
Set to true to not create the primary key. |
# File lib/sequel/database/schema_methods.rb, line 120 def create_join_table(hash, options={}) keys = hash.keys.sort_by{|k| k.to_s} create_table(join_table_name(hash, options), options) do keys.each do |key| v = hash[key] unless v.is_a?(Hash) v = {:table=>v} end v = DEFAULT_JOIN_TABLE_COLUMN_OPTIONS.merge(v) foreign_key(key, v) end primary_key(keys) unless options[:no_primary_key] index(keys.reverse, options[:index_options] || {}) unless options[:no_index] end end
Creates a view, replacing a view with the same name if one already exists.
DB.create_or_replace_view(:some_items, "SELECT * FROM items WHERE price < 100") DB.create_or_replace_view(:some_items, DB[:items].filter(:category => 'ruby'))
For databases where replacing a view is not natively supported, support is emulated by dropping a view with the same name before creating the view.
# File lib/sequel/database/schema_methods.rb, line 212 def create_or_replace_view(name, source, options = {}) if supports_create_or_replace_view? options = options.merge(:replace=>true) else drop_view(name) rescue nil end create_view(name, source, options) end
Creates a table with the columns given in the provided block:
DB.create_table :posts do primary_key :id column :title, :text String :content index :title end
General options:
:as |
Create the table using the value, which should be either a dataset or a literal SQL string. If this option is used, a block should not be given to the method. |
:ignore_index_errors |
Ignore any errors when creating indexes. |
:temp |
Create the table as a temporary table. |
MySQL specific options:
:charset |
The character set to use for the table. |
:collate |
The collation to use for the table. |
:engine |
The table engine to use for the table. |
PostgreSQL specific options:
:unlogged |
Create the table as an unlogged table. |
See Schema::Generator and the "Schema Modification" guide.
# File lib/sequel/database/schema_methods.rb, line 161 def create_table(name, options={}, &block) remove_cached_schema(name) options = {:generator=>options} if options.is_a?(Schema::CreateTableGenerator) if sql = options[:as] raise(Error, "can't provide both :as option and block to create_table") if block create_table_as(name, sql, options) else generator = options[:generator] || create_table_generator(&block) create_table_from_generator(name, generator, options) create_table_indexes_from_generator(name, generator, options) nil end end
Forcibly create a table, attempting to drop it if it already exists, then creating it.
DB.create_table!(:a){Integer :a} # SELECT NULL FROM a LIMIT 1 -- check existence # DROP TABLE a -- drop table if already exists # CREATE TABLE a (a integer)
# File lib/sequel/database/schema_methods.rb, line 181 def create_table!(name, options={}, &block) drop_table?(name) create_table(name, options, &block) end
Creates the table unless the table already exists.
DB.create_table?(:a){Integer :a} # SELECT NULL FROM a LIMIT 1 -- check existence # CREATE TABLE a (a integer) -- if it doesn't already exist
# File lib/sequel/database/schema_methods.rb, line 191 def create_table?(name, options={}, &block) if supports_create_table_if_not_exists? create_table(name, options.merge(:if_not_exists=>true), &block) elsif !table_exists?(name) create_table(name, options, &block) end end
Return a new Schema::CreateTableGenerator instance with the receiver as the database and the given block.
# File lib/sequel/database/schema_methods.rb, line 201 def create_table_generator(&block) create_table_generator_class.new(self, &block) end
Creates a view based on a dataset or an SQL string:
DB.create_view(:cheap_items, "SELECT * FROM items WHERE price < 100") DB.create_view(:ruby_items, DB[:items].filter(:category => 'ruby'))
PostgreSQL/SQLite specific option:
:temp |
Create a temporary view, automatically dropped on disconnect. |
# File lib/sequel/database/schema_methods.rb, line 229 def create_view(name, source, options = {}) execute_ddl(create_view_sql(name, source, options)) remove_cached_schema(name) nil end
Removes a column from the specified table:
DB.drop_column :items, :category
See alter_table.
# File lib/sequel/database/schema_methods.rb, line 240 def drop_column(table, *args) alter_table(table) {drop_column(*args)} end
Removes an index for the given table and column/s:
DB.drop_index :posts, :title DB.drop_index :posts, [:author, :title]
See alter_table.
# File lib/sequel/database/schema_methods.rb, line 250 def drop_index(table, columns, options={}) alter_table(table){drop_index(columns, options)} end
Drop the join table that would have been created with the same arguments to create_join_table:
drop_join_table(:cat_id=>:cats, :dog_id=>:dogs) # DROP TABLE cats_dogs
# File lib/sequel/database/schema_methods.rb, line 259 def drop_join_table(hash, options={}) drop_table(join_table_name(hash, options), options) end
Drops one or more tables corresponding to the given names:
DB.drop_table(:posts) # DROP TABLE posts DB.drop_table(:posts, :comments) DB.drop_table(:posts, :comments, :cascade=>true)
# File lib/sequel/database/schema_methods.rb, line 268 def drop_table(*names) options = names.last.is_a?(Hash) ? names.pop : {} names.each do |n| execute_ddl(drop_table_sql(n, options)) remove_cached_schema(n) end nil end
Drops the table if it already exists. If it doesn't exist, does nothing.
DB.drop_table?(:a) # SELECT NULL FROM a LIMIT 1 -- check existence # DROP TABLE a -- if it already exists
# File lib/sequel/database/schema_methods.rb, line 283 def drop_table?(*names) options = names.last.is_a?(Hash) ? names.pop : {} if supports_drop_table_if_exists? options = options.merge(:if_exists=>true) names.each do |name| drop_table(name, options) end else names.each do |name| drop_table(name, options) if table_exists?(name) end end end
Drops one or more views corresponding to the given names:
DB.drop_view(:cheap_items) DB.drop_view(:cheap_items, :pricey_items) DB.drop_view(:cheap_items, :pricey_items, :cascade=>true)
# File lib/sequel/database/schema_methods.rb, line 302 def drop_view(*names) options = names.last.is_a?(Hash) ? names.pop : {} names.each do |n| execute_ddl(drop_view_sql(n, options)) remove_cached_schema(n) end nil end
Renames a column in the specified table. This method expects the current column name and the new column name:
DB.rename_column :items, :cntr, :counter
See alter_table.
# File lib/sequel/database/schema_methods.rb, line 328 def rename_column(table, *args) alter_table(table) {rename_column(*args)} end
Renames a table:
DB.tables #=> [:items] DB.rename_table :items, :old_items DB.tables #=> [:old_items]
# File lib/sequel/database/schema_methods.rb, line 316 def rename_table(name, new_name) execute_ddl(rename_table_sql(name, new_name)) remove_cached_schema(name) nil end
Sets the default value for the given column in the given table:
DB.set_column_default :items, :category, 'perl!'
See alter_table.
# File lib/sequel/database/schema_methods.rb, line 337 def set_column_default(table, *args) alter_table(table) {set_column_default(*args)} end
Set the data type for the given column in the given table:
DB.set_column_type :items, :price, :float
See alter_table.
# File lib/sequel/database/schema_methods.rb, line 346 def set_column_type(table, *args) alter_table(table) {set_column_type(*args)} end
These methods all return instances of this database's dataset class.
Returns a dataset for the database. If the first argument is a string, the method acts as an alias for Database#fetch, returning a dataset for arbitrary SQL, with or without placeholders:
DB['SELECT * FROM items'].all DB['SELECT * FROM items WHERE name = ?', my_name].all
Otherwise, acts as an alias for Database#from, setting the primary table for the dataset:
DB[:items].sql #=> "SELECT * FROM items"
# File lib/sequel/database/dataset.rb, line 19 def [](*args) args.first.is_a?(String) ? fetch(*args) : from(*args) end
Returns a blank dataset for this database.
DB.dataset # SELECT * DB.dataset.from(:items) # SELECT * FROM items
# File lib/sequel/database/dataset.rb, line 27 def dataset(opts=(no_arg_given=true; nil)) # REMOVE40 if no_arg_given @dataset_class.new(self) else @dataset_class.new(self, opts) end end
Fetches records for an arbitrary SQL statement. If a block is given, it is used to iterate over the records:
DB.fetch('SELECT * FROM items'){|r| p r}
The fetch method returns a dataset instance:
DB.fetch('SELECT * FROM items').all
fetch can also perform parameterized queries for protection against SQL injection:
DB.fetch('SELECT * FROM items WHERE name = ?', my_name).all
# File lib/sequel/database/dataset.rb, line 49 def fetch(sql, *args, &block) ds = @default_dataset.with_sql(sql, *args) ds.each(&block) if block ds end
Returns a new dataset with the from method invoked. If a block is given, it is used as a filter on the dataset.
DB.from(:items) # SELECT * FROM items DB.from(:items){id > 2} # SELECT * FROM items WHERE (id > 2)
# File lib/sequel/database/dataset.rb, line 60 def from(*args, &block) ds = @default_dataset.from(*args) block ? ds.filter(&block) : ds end
Returns a new dataset with the select method invoked.
DB.select(1) # SELECT 1 DB.select{server_version{}} # SELECT server_version() DB.select(:id).from(:items) # SELECT id FROM items
# File lib/sequel/database/dataset.rb, line 70 def select(*args, &block) @default_dataset.select(*args, &block) end
This methods involve the Database's connection pool.
The Database subclass for the given adapter scheme. Raises Sequel::AdapterNotFound if the adapter could not be loaded.
# File lib/sequel/database/connecting.rb, line 21 def self.adapter_class(scheme) return scheme if scheme.is_a?(Class) scheme = scheme.to_s.gsub('-', '_').to_sym unless klass = ADAPTER_MAP[scheme] # attempt to load the adapter file begin require "sequel/adapters/#{scheme}" rescue LoadError => e raise Sequel.convert_exception_class(e, AdapterNotFound) end # make sure we actually loaded the adapter unless klass = ADAPTER_MAP[scheme] raise AdapterNotFound, "Could not load #{scheme} adapter: adapter class not registered in ADAPTER_MAP" end end klass end
Returns the scheme symbol for the Database class.
# File lib/sequel/database/connecting.rb, line 43 def self.adapter_scheme @scheme end
Connects to a database. See Sequel.connect.
# File lib/sequel/database/connecting.rb, line 48 def self.connect(conn_string, opts = {}) case conn_string when String if match = /\A(jdbc|do):/.match(conn_string) c = adapter_class(match[1].to_sym) opts = opts.merge(:orig_opts=>opts.dup) opts = {:uri=>conn_string}.merge(opts) else uri = URI.parse(conn_string) scheme = uri.scheme scheme = :dbi if scheme =~ /\Adbi-/ c = adapter_class(scheme) uri_options = c.send(:uri_to_options, uri) uri.query.split('&').collect{|s| s.split('=')}.each{|k,v| uri_options[k.to_sym] = v if k && !k.empty?} unless uri.query.to_s.strip.empty? uri_options.to_a.each{|k,v| uri_options[k] = (defined?(URI::DEFAULT_PARSER) ? URI::DEFAULT_PARSER : URI).unescape(v) if v.is_a?(String)} opts = uri_options.merge(opts).merge!(:orig_opts=>opts.dup, :uri=>conn_string, :adapter=>scheme) end when Hash opts = conn_string.merge(opts) opts = opts.merge(:orig_opts=>opts.dup) c = adapter_class(opts[:adapter_class] || opts[:adapter] || opts['adapter']) else raise Error, "Sequel::Database.connect takes either a Hash or a String, given: #{conn_string.inspect}" end # process opts a bit opts = opts.inject({}) do |m, (k,v)| k = :user if k.to_s == 'username' m[k.to_sym] = v m end begin db = c.new(opts) db.test_connection if opts[:test] && db.send(:typecast_value_boolean, opts[:test]) if block_given? return yield(db) end ensure if block_given? db.disconnect if db Sequel.synchronize{::Sequel::DATABASES.delete(db)} end end db end
Returns the scheme symbol for this instance's class, which reflects which adapter is being used. In some cases, this can be the same as the database_type (for native adapters), in others (i.e. adapters with subadapters), it will be different.
Sequel.connect('jdbc:postgres://...').adapter_scheme # => :jdbc
# File lib/sequel/database/connecting.rb, line 121 def adapter_scheme self.class.adapter_scheme end
Dynamically add new servers or modify server options at runtime. Also adds new servers to the connection pool. Intended for use with master/slave or shard configurations where it is useful to add new server hosts at runtime.
servers argument should be a hash with server name symbol keys and hash or proc values. If a servers key is already in use, it's value is overridden with the value provided.
DB.add_servers(:f=>{:host=>"hash_host_f"})
# File lib/sequel/database/connecting.rb, line 134 def add_servers(servers) if h = @opts[:servers] Sequel.synchronize{h.merge!(servers)} @pool.add_servers(servers.keys) end end
Connects to the database. This method should be overridden by descendants.
# File lib/sequel/database/connecting.rb, line 142 def connect(server) Sequel::Deprecation.deprecate('Database#connect default implementation and Sequel::NotImplemented', 'All database instance can be assumed to implement connect.') raise NotImplemented, "#connect should be overridden by adapters" end
The database type for this database object, the same as the adapter scheme by default. Should be overridden in adapters (especially shared adapters) to be the correct type, so that even if two separate Database objects are using different adapters you can tell that they are using the same database type. Even better, you can tell that two Database objects that are using the same adapter are connecting to different database types (think JDBC or DataObjects).
Sequel.connect('jdbc:postgres://...').database_type # => :postgres
# File lib/sequel/database/connecting.rb, line 156 def database_type adapter_scheme end
Disconnects all available connections from the connection pool. Any connections currently in use will not be disconnected. Options:
:servers |
Should be a symbol specifing the server to disconnect from, or an array of symbols to specify multiple servers. |
Example:
DB.disconnect # All servers DB.disconnect(:servers=>:server1) # Single server DB.disconnect(:servers=>[:server1, :server2]) # Multiple servers
# File lib/sequel/database/connecting.rb, line 170 def disconnect(opts = {}) pool.disconnect(opts) end
Should only be called by the connection pool code to disconnect a connection. By default, calls the close method on the connection object, since most adapters use that, but should be overwritten on other adapters.
# File lib/sequel/database/connecting.rb, line 177 def disconnect_connection(conn) conn.close end
Yield a new Database instance for every server in the connection pool. Intended for use in sharded environments where there is a need to make schema modifications (DDL queries) on each shard.
DB.each_server{|db| db.create_table(:users){primary_key :id; String :name}}
# File lib/sequel/database/connecting.rb, line 186 def each_server(&block) raise(Error, "Database#each_server must be passed a block") unless block servers.each{|s| self.class.connect(server_opts(s), &block)} end
Dynamically remove existing servers from the connection pool. Intended for use with master/slave or shard configurations where it is useful to remove existing server hosts at runtime.
servers should be symbols or arrays of symbols. If a nonexistent server is specified, it is ignored. If no servers have been specified for this database, no changes are made. If you attempt to remove the :default server, an error will be raised.
DB.remove_servers(:f1, :f2)
# File lib/sequel/database/connecting.rb, line 201 def remove_servers(*servers) if h = @opts[:servers] servers.flatten.each{|s| Sequel.synchronize{h.delete(s)}} @pool.remove_servers(servers) end end
An array of servers/shards for this Database object.
DB.servers # Unsharded: => [:default] DB.servers # Sharded: => [:default, :server1, :server2]
# File lib/sequel/database/connecting.rb, line 212 def servers pool.servers end
Returns true if the database is using a single-threaded connection pool.
# File lib/sequel/database/connecting.rb, line 217 def single_threaded? @single_threaded end
Acquires a database connection, yielding it to the passed block. This is useful if you want to make sure the same connection is used for all database queries in the block. It is also useful if you want to gain direct access to the underlying connection object if you need to do something Sequel does not natively support.
If a server option is given, acquires a connection for that specific server, instead of the :default server.
DB.synchronize do |conn| ... end
# File lib/sequel/database/connecting.rb, line 234 def synchronize(server=nil) @pool.hold(server || :default){|conn| yield conn} end
Attempts to acquire a database connection. Returns true if successful. Will probably raise an Error if unsuccessful. If a server argument is given, attempts to acquire a database connection to the given server/shard.
# File lib/sequel/database/connecting.rb, line 249 def test_connection(server=nil) synchronize(server){|conn|} true end
Check whether the given connection is currently valid, by running a query against it. If the query fails, the connection should probably be removed from the connection pool.
# File lib/sequel/database/connecting.rb, line 258 def valid_connection?(conn) sql = valid_connection_sql begin log_connection_execute(conn, sql) rescue Sequel::DatabaseError, *database_error_classes false else true end end
This methods change the default behavior of this database's datasets.
The default class to use for datasets
The identifier input method to use by default for all databases (default: adapter default)
The identifier output method to use by default for all databases (default: adapter default)
Whether to quote identifiers (columns and tables) by default for all databases (default: adapter default)
The class to use for creating datasets. Should respond to new with the Database argument as the first argument, and an optional options hash.
REMOVE40
# File lib/sequel/database/dataset_defaults.rb, line 48 def _default_schema @default_schema end
If the database has any dataset modules associated with it, use a subclass of the given class that includes the modules as the dataset class.
# File lib/sequel/database/dataset_defaults.rb, line 63 def dataset_class=(c) unless @dataset_modules.empty? c = Class.new(c) @dataset_modules.each{|m| c.send(:include, m)} end @dataset_class = c reset_default_dataset end
# File lib/sequel/database/dataset_defaults.rb, line 51 def default_schema Sequel::Deprecation.deprecate('Database#default_schema', 'Use qualified tables instead') @default_schema end
# File lib/sequel/database/dataset_defaults.rb, line 55 def default_schema=(v) Sequel::Deprecation.deprecate('Database#default_schema=', 'Use qualified tables instead') if v @default_schema = v end
Equivalent to extending all datasets produced by the database with a module. What it actually does is use a subclass of the current dataset_class as the new dataset_class, and include the module in the subclass. Instead of a module, you can provide a block that is used to create an anonymous module.
This allows you to override any of the dataset methods even if they are defined directly on the dataset class that this Database object uses.
Examples:
# Introspec columns for all of DB's datasets DB.extend_datasets(Sequel::ColumnsIntrospection) # Trace all SELECT queries by printing the SQL and the full backtrace DB.extend_datasets do def fetch_rows(sql) puts sql puts caller super end end
# File lib/sequel/database/dataset_defaults.rb, line 94 def extend_datasets(mod=nil, &block) raise(Error, "must provide either mod or block, not both") if mod && block mod = Module.new(&block) if block if @dataset_modules.empty? @dataset_modules = [mod] @dataset_class = Class.new(@dataset_class) else @dataset_modules << mod end @dataset_class.send(:include, mod) reset_default_dataset end
Set the method to call on identifiers going into the database:
DB[:items] # SELECT * FROM items DB.identifier_input_method = :upcase DB[:items] # SELECT * FROM ITEMS
# File lib/sequel/database/dataset_defaults.rb, line 112 def identifier_input_method=(v) reset_default_dataset @identifier_input_method = v end
Set the method to call on identifiers coming from the database:
DB[:items].first # {:id=>1, :name=>'foo'} DB.identifier_output_method = :upcase DB[:items].first # {:ID=>1, :NAME=>'foo'}
# File lib/sequel/database/dataset_defaults.rb, line 122 def identifier_output_method=(v) reset_default_dataset @identifier_output_method = v end
Set whether to quote identifiers (columns and tables) for this database:
DB[:items] # SELECT * FROM items DB.quote_identifiers = true DB[:items] # SELECT * FROM "items"
# File lib/sequel/database/dataset_defaults.rb, line 132 def quote_identifiers=(v) reset_default_dataset @quote_identifiers = v end
This methods affect relating to the logging of executed SQL.
Numeric specifying the duration beyond which queries are logged at warn level instead of info level.
Log level at which to log SQL queries. This is actually the method sent to the logger, so it should be the method name symbol. The default is :info, it can be set to :debug to log at DEBUG level.
Log a message at error level, with information about the exception.
# File lib/sequel/database/logging.rb, line 21 def log_exception(exception, message) log_each(:error, "#{exception.class}: #{exception.message.strip if exception.message}: #{message}") end
Log a message at level info to all loggers.
# File lib/sequel/database/logging.rb, line 26 def log_info(message, args=nil) log_each(:info, args ? "#{message}; #{args.inspect}" : message) end
Yield to the block, logging any errors at error level to all loggers, and all other queries with the duration at warn or info level.
# File lib/sequel/database/logging.rb, line 32 def log_yield(sql, args=nil) return yield if @loggers.empty? sql = "#{sql}; #{args.inspect}" if args start = Time.now begin yield rescue => e log_exception(e, sql) raise ensure log_duration(Time.now - start, sql) unless e end end
These methods don't fit neatly into another category.
Empty exception regexp to class map, used by default if Sequel doesn't have specific support for the database in use.
The general default size for string columns for all Sequel::Database instances.
Hash of extension name symbols to callable objects to load the extension into the Database object (usually by extending it with a module defined in the extension).
Used for checking/removing leading zeroes from strings so they don't get interpreted as octal.
:nocov: Replacement string when replacing leading zeroes.
Mapping of schema type symbols to class or arrays of classes for that symbol.
The specific default size of string columns for this Sequel::Database, usually 255 by default.
Register a hook that will be run when a new Database is instantiated. It is called with the new database handle.
# File lib/sequel/database/misc.rb, line 40 def self.after_initialize(&block) raise Error, "must provide block to after_initialize" unless block Sequel.synchronize do previous = @initialize_hook @initialize_hook = Proc.new do |db| previous.call(db) block.call(db) end end end
Apply an extension to all Database objects created in the future.
# File lib/sequel/database/misc.rb, line 52 def self.extension(*extensions) after_initialize{|db| db.extension(*extensions)} end
Constructs a new instance of a database connection with the specified options hash.
Accepts the following options:
The default size of string columns, 255 by default. | |
A string method symbol to call on identifiers going into the database | |
A string method symbol to call on identifiers coming from the database | |
:logger |
A specific logger to use |
:loggers |
An array of loggers to use |
Whether to quote identifiers | |
:servers |
A hash specifying a server/shard specific options, keyed by shard symbol |
Whether to use a single-threaded connection pool | |
Method to use to log SQL to a logger, :info by default. |
All options given are also passed to the connection pool.
# File lib/sequel/database/misc.rb, line 113 def initialize(opts = {}, &block) @opts ||= opts @opts = connection_pool_default_options.merge(@opts) @loggers = Array(@opts[:logger]) + Array(@opts[:loggers]) self.log_warn_duration = @opts[:log_warn_duration] block ||= proc{|server| connect(server)} @opts[:servers] = {} if @opts[:servers].is_a?(String) @opts[:adapter_class] = self.class @opts[:single_threaded] = @single_threaded = typecast_value_boolean(@opts.fetch(:single_threaded, Database.single_threaded)) @schemas = {} @default_schema = @opts.fetch(:default_schema, default_schema_default) @default_string_column_size = @opts[:default_string_column_size] || DEFAULT_STRING_COLUMN_SIZE @prepared_statements = {} @transactions = {} @identifier_input_method = nil @identifier_output_method = nil @quote_identifiers = nil @timezone = nil @dataset_class = dataset_class_default @cache_schema = typecast_value_boolean(@opts.fetch(:cache_schema, true)) @dataset_modules = [] @schema_type_classes = SCHEMA_TYPE_CLASSES.dup self.sql_log_level = @opts[:sql_log_level] ? @opts[:sql_log_level].to_sym : :info @pool = ConnectionPool.get_pool(self, @opts) reset_identifier_mangling adapter_initialize unless typecast_value_boolean(@opts[:keep_reference]) == false Sequel.synchronize{::Sequel::DATABASES.push(self)} end Sequel::Database.run_after_initialize(self) end
Register an extension callback for Database objects. ext should be the extension name symbol, and mod should either be a Module that the database is extended with, or a callable object called with the database object. If mod is not provided, a block can be provided and is treated as the mod object.
# File lib/sequel/database/misc.rb, line 61 def self.register_extension(ext, mod=nil, &block) if mod raise(Error, "cannot provide both mod and block to Database.register_extension") if block if mod.is_a?(Module) block = proc{|db| db.extend(mod)} else block = mod end end Sequel.synchronize{EXTENSIONS[ext] = block} end
Run the after_initialize hook for the given instance.
# File lib/sequel/database/misc.rb, line 74 def self.run_after_initialize(instance) @initialize_hook.call(instance) end
If a transaction is not currently in process, yield to the block immediately. Otherwise, add the block to the list of blocks to call after the currently in progress transaction commits (and only if it commits). Options:
:server |
The server/shard to use. |
# File lib/sequel/database/misc.rb, line 153 def after_commit(opts={}, &block) raise Error, "must provide block to after_commit" unless block synchronize(opts[:server]) do |conn| if h = _trans(conn) raise Error, "cannot call after_commit in a prepared transaction" if h[:prepare] (h[:after_commit] ||= []) << block else yield end end end
If a transaction is not currently in progress, ignore the block. Otherwise, add the block to the list of the blocks to call after the currently in progress transaction rolls back (and only if it rolls back). Options:
:server |
The server/shard to use. |
# File lib/sequel/database/misc.rb, line 170 def after_rollback(opts={}, &block) raise Error, "must provide block to after_rollback" unless block synchronize(opts[:server]) do |conn| if h = _trans(conn) raise Error, "cannot call after_rollback in a prepared transaction" if h[:prepare] (h[:after_rollback] ||= []) << block end end end
Cast the given type to a literal type
DB.cast_type_literal(Float) # double precision DB.cast_type_literal(:foo) # foo
# File lib/sequel/database/misc.rb, line 184 def cast_type_literal(type) type_literal(:type=>type) end
Load an extension into the receiver. In addition to requiring the extension file, this also modifies the database to work with the extension (usually extending it with a module defined in the extension file). If no related extension file exists or the extension does not have specific support for Database objects, an Error will be raised. Returns self.
# File lib/sequel/database/misc.rb, line 193 def extension(*exts) Sequel.extension(*exts) exts.each do |ext| if pr = Sequel.synchronize{EXTENSIONS[ext]} pr.call(self) else raise(Error, "Extension #{ext} does not have specific support handling individual databases") end end self end
Convert the given timestamp from the application's timezone, to the databases's timezone or the default database timezone if the database does not have a timezone.
# File lib/sequel/database/misc.rb, line 208 def from_application_timestamp(v) Sequel.convert_output_timestamp(v, timezone) end
Return true if already in a transaction given the options, false otherwise. Respects the :server option for selecting a shard.
# File lib/sequel/database/misc.rb, line 215 def in_transaction?(opts={}) synchronize(opts[:server]){|conn| !!_trans(conn)} end
Returns a string representation of the database object including the class name and connection URI and options used when connecting (if any).
# File lib/sequel/database/misc.rb, line 221 def inspect a = [] a << uri.inspect if uri if (oo = opts[:orig_opts]) && !oo.empty? a << oo.inspect end "#<#{self.class}: #{a.join(' ')}>" end
Proxy the literal call to the dataset.
DB.literal(1) # 1 DB.literal(:a) # a DB.literal('a') # 'a'
# File lib/sequel/database/misc.rb, line 235 def literal(v) schema_utility_dataset.literal(v) end
Synchronize access to the prepared statements cache.
# File lib/sequel/database/misc.rb, line 240 def prepared_statement(name) Sequel.synchronize{prepared_statements[name]} end
Proxy the quote_identifier method to the dataset, useful for quoting unqualified identifiers for use outside of datasets.
# File lib/sequel/database/misc.rb, line 247 def quote_identifier(v) schema_utility_dataset.quote_identifier(v) end
Return ruby class or array of classes for the given type symbol.
# File lib/sequel/database/misc.rb, line 252 def schema_type_class(type) @schema_type_classes[type] end
Default serial primary key options, used by the table creation code.
# File lib/sequel/database/misc.rb, line 258 def serial_primary_key_options {:primary_key => true, :type => Integer, :auto_increment => true} end
Cache the prepared statement object at the given name.
# File lib/sequel/database/misc.rb, line 263 def set_prepared_statement(name, ps) ps.prepared_sql Sequel.synchronize{prepared_statements[name] = ps} end
The timezone to use for this database, defaulting to Sequel.database_timezone.
# File lib/sequel/database/misc.rb, line 269 def timezone @timezone || Sequel.database_timezone end
Convert the given timestamp to the application's timezone, from the databases's timezone or the default database timezone if the database does not have a timezone.
# File lib/sequel/database/misc.rb, line 276 def to_application_timestamp(v) Sequel.convert_timestamp(v, timezone) end
Typecast the value to the given column_type. Calls typecast_value_#{column_type} if the method exists, otherwise returns the value. This method should raise Sequel::InvalidValue if assigned value is invalid.
# File lib/sequel/database/misc.rb, line 285 def typecast_value(column_type, value) return nil if value.nil? meth = "typecast_value_#{column_type}" begin respond_to?(meth, true) ? send(meth, value) : value rescue ArgumentError, TypeError => e raise Sequel.convert_exception_class(e, InvalidValue) end end
These methods all return booleans, with most describing whether or not the database supprots a given feature.
Whether the database uses a global namespace for the index. If false, the indexes are going to be namespaced per table.
# File lib/sequel/database/features.rb, line 11 def global_index_namespace? true end
Whether the database supports CREATE TABLE IF NOT EXISTS syntax, false by default.
# File lib/sequel/database/features.rb, line 17 def supports_create_table_if_not_exists? false end
Whether the database supports deferrable constraints, false by default as few databases do.
# File lib/sequel/database/features.rb, line 23 def supports_deferrable_constraints? false end
Whether the database supports deferrable foreign key constraints, false by default as few databases do.
# File lib/sequel/database/features.rb, line 29 def supports_deferrable_foreign_key_constraints? supports_deferrable_constraints? end
Whether the database supports DROP TABLE IF EXISTS syntax, default is the same as supports_create_table_if_not_exists?.
# File lib/sequel/database/features.rb, line 35 def supports_drop_table_if_exists? supports_create_table_if_not_exists? end
Whether the database supports Database#foreign_key_list for parsing foreign keys.
# File lib/sequel/database/features.rb, line 41 def supports_foreign_key_parsing? [:access, :mssql, :mysql, :postgres, :sqlite].include?(database_type) end
Whether the database supports Database#indexes for parsing indexes.
# File lib/sequel/database/features.rb, line 46 def supports_index_parsing? [:access, :cubrid, :db2, :mssql, :mysql, :postgres, :sqlite].include?(database_type) || adapter_scheme == :jdbc end
Whether the database and adapter support prepared transactions (two-phase commit), false by default.
# File lib/sequel/database/features.rb, line 52 def supports_prepared_transactions? false end
Whether the database and adapter support savepoints, false by default.
# File lib/sequel/database/features.rb, line 57 def supports_savepoints? false end
Whether the database and adapter support savepoints inside prepared transactions (two-phase commit), default is false.
# File lib/sequel/database/features.rb, line 63 def supports_savepoints_in_prepared_transactions? supports_prepared_transactions? && supports_savepoints? end
Whether the database supports schema parsing via Database#schema.
# File lib/sequel/database/features.rb, line 68 def supports_schema_parsing? respond_to?(:schema_parse_table, true) end
Whether the database supports Database#tables for getting list of tables.
# File lib/sequel/database/features.rb, line 73 def supports_table_listing? [:access, :cubrid, :db2, :firebird, :mssql, :mysql, :oracle, :postgres, :sqlite].include?(database_type) || adapter_scheme == :jdbc end
Whether the database and adapter support transaction isolation levels, false by default.
# File lib/sequel/database/features.rb, line 83 def supports_transaction_isolation_levels? false end
Whether DDL statements work correctly in transactions, false by default.
# File lib/sequel/database/features.rb, line 88 def supports_transactional_ddl? false end
Whether the database supports Database#views for getting list of views.
# File lib/sequel/database/features.rb, line 78 def supports_view_listing? supports_table_listing? end
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