module Sequel::Model::DatasetMethods

DatasetMethods contains methods that all model datasets have.

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
Calls superclass method
     # File lib/sequel/model/base.rb
2121 def [](*args)
2122   if args.length == 1 && (i = args[0]) && i.is_a?(Integer)
2123     with_pk(i)
2124   else
2125     super
2126   end
2127 end
as_hash(key_column=nil, value_column=nil, opts=OPTS) click to toggle source

This allows you to call as_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.as_hash # SELECT * FROM artists
# => {1=>#<Artist {:id=>1, ...}>,
#     2=>#<Artist {:id=>2, ...}>,
#     ...}
Calls superclass method
     # File lib/sequel/model/base.rb
2180 def as_hash(key_column=nil, value_column=nil, opts=OPTS)
2181   if key_column
2182     super
2183   else
2184     raise(Sequel::Error, "No primary key for model") unless model && (pk = model.primary_key)
2185     super(pk, value_column, opts) 
2186   end
2187 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
2138 def destroy
2139   pr = proc{all(&:destroy).length}
2140   model.use_transactions ? @db.transaction(:server=>opts[:server], &pr) : pr.call
2141 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
Calls superclass method
     # File lib/sequel/model/base.rb
2148 def last(*a, &block)
2149   if ds = _primary_key_order
2150     ds.last(*a, &block)
2151   else
2152     super
2153   end
2154 end
model() click to toggle source

The model class associated with this dataset

Artist.dataset.model # => Artist
     # File lib/sequel/model/base.rb
2113 def model
2114   @opts[:model]
2115 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
# ...
Calls superclass method
     # File lib/sequel/model/base.rb
2164 def paged_each(*a, &block)
2165   if ds = _primary_key_order
2166     ds.paged_each(*a, &block)
2167   else
2168     super
2169   end
2170 end
to_hash(*a) click to toggle source

Alias of as_hash for backwards compatibility.

     # File lib/sequel/model/base.rb
2190 def to_hash(*a)
2191   as_hash(*a)
2192 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 (artists.id = 1) LIMIT 1

# Composite primary key
Artist.dataset.with_pk([1, 2])
# SELECT * FROM artists WHERE ((artists.id1 = 1) AND (artists.id2 = 2)) LIMIT 1
     # File lib/sequel/model/base.rb
2204 def with_pk(pk)
2205   if pk && (loader = _with_pk_loader)
2206     loader.first(*pk)
2207   else
2208     first(model.qualified_primary_key_hash(pk))
2209   end
2210 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
2214 def with_pk!(pk)
2215   with_pk(pk) || raise(NoMatchingRow.new(self))
2216 end

Private Instance Methods

_primary_key_order() click to toggle source

If the dataset is not already ordered, and the model has a primary key, return a clone ordered by the primary key.

     # File lib/sequel/model/base.rb
2222 def _primary_key_order
2223   if @opts[:order].nil? && model && (pk = model.primary_key)
2224     cached_dataset(:_pk_order_ds){order(*pk)}
2225   end
2226 end
_with_pk_loader() click to toggle source

A cached placeholder literalizer, if one exists for the current dataset.

     # File lib/sequel/model/base.rb
2229 def _with_pk_loader
2230   cached_placeholder_literalizer(:_with_pk_loader) do |pl|
2231     table = model.table_name
2232     cond = case primary_key = model.primary_key
2233     when Array
2234       primary_key.map{|key| [SQL::QualifiedIdentifier.new(table, key), pl.arg]}
2235     when Symbol
2236       {SQL::QualifiedIdentifier.new(table, primary_key)=>pl.arg}
2237     else
2238       raise(Error, "#{model} does not have a primary key")
2239     end
2240 
2241     where(cond).limit(1)
2242   end
2243 end
non_sql_option?(key) click to toggle source
Calls superclass method
     # File lib/sequel/model/base.rb
2245 def non_sql_option?(key)
2246   super || key == :model
2247 end