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Sequel::Model::DatasetMethods

Dataset methods are methods that the model class extends its dataset with in the call to set_dataset.

Attributes

model[RW]

The model class associated with this dataset

Artist.dataset.model # => Artist

Public Instance Methods

[](*args) click to toggle source

Assume if a single integer is given that it is a lookup by primary key, and call with_pk with the argument.

Artist.dataset[1] # SELECT * FROM artists WHERE (id = 1) LIMIT 1
# File lib/sequel/model/base.rb, line 2025
def [](*args)
  if args.length == 1 && (i = args.at(0)) && i.is_a?(Integer)
    with_pk(i)
  else
    super
  end
end
destroy() click to toggle source

Destroy each row in the dataset by instantiating it and then calling destroy on the resulting model object. This isn't as fast as deleting the dataset, which does a single SQL call, but this runs any destroy hooks on each object in the dataset.

Artist.dataset.destroy
# DELETE FROM artists WHERE (id = 1)
# DELETE FROM artists WHERE (id = 2)
# ...
# File lib/sequel/model/base.rb, line 2042
def destroy
  pr = proc{all{|r| r.destroy}.length}
  model.use_transactions ? @db.transaction(:server=>opts[:server], &pr) : pr.call
end
graph(table, *args, &block) click to toggle source

Allow Sequel::Model classes to be used as dataset arguments when graphing:

Artist.graph(Album, :artist_id=>id)
# SELECT artists.id, artists.name, albums.id AS albums_id, albums.artist_id, albums.name AS albums_name
# FROM artists LEFT OUTER JOIN albums ON (albums.artist_id = artists.id)
# File lib/sequel/model/base.rb, line 2052
def graph(table, *args, &block)
  if table.is_a?(Class) && table < Sequel::Model
    super(table.dataset, *args, &block)
  else
    super
  end
end
insert_sql(*values) click to toggle source

Handle Sequel::Model instances when inserting, using the model instance's values for the insert, unless the model instance can be used directly in SQL.

Album.insert(Album.load(:name=>'A'))
# INSERT INTO albums (name) VALUES ('A')
# File lib/sequel/model/base.rb, line 2066
def insert_sql(*values)
  if values.size == 1 && (v = values.at(0)).is_a?(Sequel::Model) && !v.respond_to?(:sql_literal_append)
    super(v.to_hash)
  else
    super
  end
end
join_table(type, table, *args, &block) click to toggle source

Allow Sequel::Model classes to be used as table name arguments in dataset join methods:

Artist.join(Album, :artist_id=>id)
# SELECT * FROM artists INNER JOIN albums ON (albums.artist_id = artists.id)
# File lib/sequel/model/base.rb, line 2079
def join_table(type, table, *args, &block)
  if table.is_a?(Class) && table < Sequel::Model
    if table.dataset.simple_select_all?
      super(type, table.table_name, *args, &block)
    else
      super(type, table.dataset, *args, &block)
    end
  else
    super
  end
end
last(*a, &block) click to toggle source

If there is no order already defined on this dataset, order it by the primary key and call last.

Album.last
# SELECT * FROM albums ORDER BY id DESC LIMIT 1
# File lib/sequel/model/base.rb, line 2096
def last(*a, &block)
  if opts[:order].nil? && model && (pk = model.primary_key)
    order(*pk).last(*a, &block)
  else
    super
  end
end
paged_each(*a, &block) click to toggle source

If there is no order already defined on this dataset, order it by the primary key and call paged_each.

Album.paged_each{|row| ...}
# SELECT * FROM albums ORDER BY id LIMIT 1000 OFFSET 0
# SELECT * FROM albums ORDER BY id LIMIT 1000 OFFSET 1000
# SELECT * FROM albums ORDER BY id LIMIT 1000 OFFSET 2000
# ...
# File lib/sequel/model/base.rb, line 2112
def paged_each(*a, &block)
  if opts[:order].nil? && model && (pk = model.primary_key)
    order(*pk).paged_each(*a, &block)
  else
    super
  end
end
to_hash(key_column=nil, value_column=nil) click to toggle source

This allows you to call to_hash without any arguments, which will result in a hash with the primary key value being the key and the model object being the value.

Artist.dataset.to_hash # SELECT * FROM artists
# => {1=>#<Artist {:id=>1, ...}>,
#     2=>#<Artist {:id=>2, ...}>,
#     ...}
# File lib/sequel/model/base.rb, line 2128
def to_hash(key_column=nil, value_column=nil)
  if key_column
    super
  else
    raise(Sequel::Error, "No primary key for model") unless model && (pk = model.primary_key)
    super(pk, value_column) 
  end
end
with_pk(pk) click to toggle source

Given a primary key value, return the first record in the dataset with that primary key value. If no records matches, returns nil.

# Single primary key
Artist.dataset.with_pk(1) # SELECT * FROM artists WHERE (id = 1) LIMIT 1

# Composite primary key
Artist.dataset.with_pk([1, 2]) # SELECT * FROM artists
                               # WHERE ((id1 = 1) AND (id2 = 2)) LIMIT 1
# File lib/sequel/model/base.rb, line 2146
def with_pk(pk)
  first(model.qualified_primary_key_hash(pk))
end
with_pk!(pk) click to toggle source

Same as with_pk, but raises NoMatchingRow instead of returning nil if no row matches.

# File lib/sequel/model/base.rb, line 2152
def with_pk!(pk)
  with_pk(pk) || raise(NoMatchingRow)
end

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