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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 1852
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 1869
def destroy
  pr = proc{all{|r| r.destroy}.length}
  model.use_transactions ? @db.transaction(:server=>opts[:server], &pr) : pr.call
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 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
with_pk(pk) click to toggle source

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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