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
2132 def [](*args)
2133   if args.length == 1 && (i = args[0]) && i.is_a?(Integer)
2134     with_pk(i)
2135   else
2136     super
2137   end
2138 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
2191 def as_hash(key_column=nil, value_column=nil, opts=OPTS)
2192   if key_column
2193     super
2194   else
2195     raise(Sequel::Error, "No primary key for model") unless model && (pk = model.primary_key)
2196     super(pk, value_column, opts) 
2197   end
2198 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
2149 def destroy
2150   pr = proc{all(&:destroy).length}
2151   model.use_transactions ? @db.transaction(:server=>opts[:server], &pr) : pr.call
2152 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
2159 def last(*a, &block)
2160   if ds = _primary_key_order
2161     ds.last(*a, &block)
2162   else
2163     super
2164   end
2165 end
model() click to toggle source

The model class associated with this dataset

Artist.dataset.model # => Artist
     # File lib/sequel/model/base.rb
2124 def model
2125   @opts[:model]
2126 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
2175 def paged_each(*a, &block)
2176   if ds = _primary_key_order
2177     ds.paged_each(*a, &block)
2178   else
2179     super
2180   end
2181 end
to_hash(*a) click to toggle source

Alias of as_hash for backwards compatibility.

     # File lib/sequel/model/base.rb
2201 def to_hash(*a)
2202   as_hash(*a)
2203 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
2215 def with_pk(pk)
2216   if pk && (loader = _with_pk_loader)
2217     loader.first(*pk)
2218   else
2219     first(model.qualified_primary_key_hash(pk))
2220   end
2221 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
2225 def with_pk!(pk)
2226   with_pk(pk) || raise(NoMatchingRow.new(self))
2227 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
2233 def _primary_key_order
2234   if @opts[:order].nil? && model && (pk = model.primary_key)
2235     cached_dataset(:_pk_order_ds){order(*pk)}
2236   end
2237 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
2240 def _with_pk_loader
2241   cached_placeholder_literalizer(:_with_pk_loader) do |pl|
2242     table = model.table_name
2243     cond = case primary_key = model.primary_key
2244     when Array
2245       primary_key.map{|key| [SQL::QualifiedIdentifier.new(table, key), pl.arg]}
2246     when Symbol
2247       {SQL::QualifiedIdentifier.new(table, primary_key)=>pl.arg}
2248     else
2249       raise(Error, "#{model} does not have a primary key")
2250     end
2251 
2252     where(cond).limit(1)
2253   end
2254 end
non_sql_option?(key) click to toggle source
Calls superclass method
     # File lib/sequel/model/base.rb
2256 def non_sql_option?(key)
2257   super || key == :model
2258 end