Dataset methods are methods that the model class extends its dataset with in the call to set_dataset.
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 1852 def [](*args) if args.length == 1 && (i = args.at(0)) && i.is_a?(Integer) with_pk(i) else super end end
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 1869 def destroy pr = proc{all{|r| r.destroy}.length} model.use_transactions ? @db.transaction(:server=>opts[:server], &pr) : pr.call end
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 1882 def to_hash(key_column=nil, value_column=nil) if key_column super else raise(Sequel::Error, "No primary key for model") unless model and pk = model.primary_key super(pk, value_column) end end
Given a primary key value, return the first record in the dataset with that primary key value.
# 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 1900 def with_pk(pk) first(model.qualified_primary_key_hash(pk)) end
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