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
2135 def [](*args)
2136   if args.length == 1 && (i = args[0]) && i.is_a?(Integer)
2137     with_pk(i)
2138   else
2139     super
2140   end
2141 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
2195 def as_hash(key_column=nil, value_column=nil, opts=OPTS)
2196   if key_column
2197     super
2198   else
2199     raise(Sequel::Error, "No primary key for model") unless model && (pk = model.primary_key)
2200     super(pk, value_column, opts) 
2201   end
2202 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
2152 def destroy
2153   @db.transaction(:server=>opts[:server], :skip_transaction=>model.use_transactions == false) do
2154     all(&:destroy).length
2155   end
2156 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
2163 def last(*a, &block)
2164   if ds = _primary_key_order
2165     ds.last(*a, &block)
2166   else
2167     super
2168   end
2169 end
model() click to toggle source

The model class associated with this dataset

Artist.dataset.model # => Artist
     # File lib/sequel/model/base.rb
2127 def model
2128   @opts[:model]
2129 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
2179 def paged_each(*a, &block)
2180   if ds = _primary_key_order
2181     ds.paged_each(*a, &block)
2182   else
2183     super
2184   end
2185 end
to_hash(*a) click to toggle source

Alias of as_hash for backwards compatibility.

     # File lib/sequel/model/base.rb
2205 def to_hash(*a)
2206   as_hash(*a)
2207 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
2219 def with_pk(pk)
2220   if pk && (loader = _with_pk_loader)
2221     loader.first(*pk)
2222   else
2223     first(model.qualified_primary_key_hash(pk))
2224   end
2225 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
2229 def with_pk!(pk)
2230   with_pk(pk) || raise(NoMatchingRow.new(self))
2231 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
2237 def _force_primary_key_order
2238   cached_dataset(:_pk_order_ds){order(*model.primary_key)}
2239 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
2243 def _primary_key_order
2244   if @opts[:order].nil? && model && model.primary_key
2245     _force_primary_key_order
2246   end
2247 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
2250 def _with_pk_loader
2251   cached_placeholder_literalizer(:_with_pk_loader) do |pl|
2252     table = model.table_name
2253     cond = case primary_key = model.primary_key
2254     when Array
2255       primary_key.map{|key| [SQL::QualifiedIdentifier.new(table, key), pl.arg]}
2256     when Symbol
2257       {SQL::QualifiedIdentifier.new(table, primary_key)=>pl.arg}
2258     else
2259       raise(Error, "#{model} does not have a primary key")
2260     end
2261 
2262     where(cond).limit(1)
2263   end
2264 end
non_sql_option?(key) click to toggle source
Calls superclass method
     # File lib/sequel/model/base.rb
2266 def non_sql_option?(key)
2267   super || key == :model
2268 end