module Sequel::Model::DatasetMethods

  1. lib/sequel/model/base.rb
Parent: Model

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)

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
[show source] 
# File lib/sequel/model/base.rb, line 1924
def [](*args)
  if args.length == 1 && (i = args.at(0)) && i.is_a?(Integer)
    with_pk(i)
  else
    super
  end
end
destroy ()

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)
# ...
[show source] 
# File lib/sequel/model/base.rb, line 1941
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)

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)
[show source] 
# File lib/sequel/model/base.rb, line 1951
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)

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')
[show source] 
# File lib/sequel/model/base.rb, line 1965
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)

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)
[show source] 
# File lib/sequel/model/base.rb, line 1978
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)

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
[show source] 
# File lib/sequel/model/base.rb, line 1995
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)

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
# ...
[show source] 
# File lib/sequel/model/base.rb, line 2011
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)

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, ...}>,
#     ...}
[show source] 
# File lib/sequel/model/base.rb, line 2027
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)

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
[show source] 
# File lib/sequel/model/base.rb, line 2045
def with_pk(pk)
  first(model.qualified_primary_key_hash(pk))
end
with_pk! (pk)

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

[show source] 
# File lib/sequel/model/base.rb, line 2051
def with_pk!(pk)
  with_pk(pk) || raise(NoMatchingRow)
end