Module: Sequel::Model::DatasetMethods

Defined in:
lib/sequel/model/base.rb

Overview

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

Instance Attribute Summary collapse

Instance Method Summary collapse

Instance Attribute Details

#model ⇒ Object

The model class associated with this dataset

Artist.dataset.model # => Artist



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# File 'lib/sequel/model/base.rb', line 1565

def model
  @model
end

Instance Method Details

#[](*args) ⇒ Object

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



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# File 'lib/sequel/model/base.rb', line 1571

def [](*args)
  if args.length == 1 && (i = args.at(0)) && i.is_a?(Integer)
    with_pk(i)
  else
    super
  end
end

#destroy ⇒ Object

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)
# ...



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# File 'lib/sequel/model/base.rb', line 1588

def destroy
  pr = proc{all{|r| r.destroy}.length}
  model.use_transactions ? @db.transaction(&pr) : pr.call
end

#to_hash(key_column = nil, value_column = nil) ⇒ Object

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, ...}>,
#     ...}



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# File 'lib/sequel/model/base.rb', line 1601

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) ⇒ Object

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



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# File 'lib/sequel/model/base.rb', line 1619

def with_pk(pk)
  case primary_key = model.primary_key
  when Array
    raise(Error, "single primary key given (#{pk.inspect}) when a composite primary key is expected (#{primary_key.inspect})") unless pk.is_a?(Array)
    raise(Error, "composite primary key given (#{pk.inspect}) does not match composite primary key length (#{primary_key.inspect})") if pk.length != primary_key.length
    first(primary_key.zip(pk))
  else
    raise(Error, "composite primary key given (#{pk.inspect}) when a single primary key is expected (#{primary_key.inspect})") if pk.is_a?(Array)
    first(primary_key=>pk)
  end
end