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
2138 def [](*args)
2139   if args.length == 1 && (i = args[0]) && i.is_a?(Integer)
2140     with_pk(i)
2141   else
2142     super
2143   end
2144 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
2198 def as_hash(key_column=nil, value_column=nil, opts=OPTS)
2199   if key_column
2200     super
2201   else
2202     raise(Sequel::Error, "No primary key for model") unless model && (pk = model.primary_key)
2203     super(pk, value_column, opts) 
2204   end
2205 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
2155 def destroy
2156   @db.transaction(:server=>opts[:server], :skip_transaction=>model.use_transactions == false) do
2157     all(&:destroy).length
2158   end
2159 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
2166 def last(*a, &block)
2167   if ds = _primary_key_order
2168     ds.last(*a, &block)
2169   else
2170     super
2171   end
2172 end
model() click to toggle source

The model class associated with this dataset

Artist.dataset.model # => Artist
     # File lib/sequel/model/base.rb
2130 def model
2131   @opts[:model]
2132 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
2182 def paged_each(*a, &block)
2183   if ds = _primary_key_order
2184     ds.paged_each(*a, &block)
2185   else
2186     super
2187   end
2188 end
to_hash(*a) click to toggle source

Alias of as_hash for backwards compatibility.

     # File lib/sequel/model/base.rb
2208 def to_hash(*a)
2209   as_hash(*a)
2210 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
2222 def with_pk(pk)
2223   if pk && (loader = _with_pk_loader)
2224     loader.first(*pk)
2225   else
2226     first(model.qualified_primary_key_hash(pk))
2227   end
2228 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
2232 def with_pk!(pk)
2233   with_pk(pk) || raise(NoMatchingRow.new(self))
2234 end

Private Instance Methods

_force_primary_key_order() click to toggle source

Return the dataset ordered by the model’s primary key. This should not be used if the model does not have a primary key.

     # File lib/sequel/model/base.rb
2240 def _force_primary_key_order
2241   cached_dataset(:_pk_order_ds){order(*model.primary_key)}
2242 end
_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
2246 def _primary_key_order
2247   if @opts[:order].nil? && model && model.primary_key
2248     _force_primary_key_order
2249   end
2250 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
2253 def _with_pk_loader
2254   cached_placeholder_literalizer(:_with_pk_loader) do |pl|
2255     table = model.table_name
2256     cond = case primary_key = model.primary_key
2257     when Array
2258       primary_key.map{|key| [SQL::QualifiedIdentifier.new(table, key), pl.arg]}
2259     when Symbol
2260       {SQL::QualifiedIdentifier.new(table, primary_key)=>pl.arg}
2261     else
2262       raise(Error, "#{model} does not have a primary key")
2263     end
2264 
2265     where(cond).limit(1)
2266   end
2267 end
non_sql_option?(key) click to toggle source
Calls superclass method
     # File lib/sequel/model/base.rb
2269 def non_sql_option?(key)
2270   super || key == :model
2271 end