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
2156 def [](*args)
2157   if args.length == 1 && (i = args[0]) && i.is_a?(Integer)
2158     with_pk(i)
2159   else
2160     super
2161   end
2162 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
2216 def as_hash(key_column=nil, value_column=nil, opts=OPTS)
2217   if key_column
2218     super
2219   else
2220     raise(Sequel::Error, "No primary key for model") unless model && (pk = model.primary_key)
2221     super(pk, value_column, opts) 
2222   end
2223 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
2173 def destroy
2174   @db.transaction(:server=>opts[:server], :skip_transaction=>model.use_transactions == false) do
2175     all(&:destroy).length
2176   end
2177 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
2184 def last(*a, &block)
2185   if ds = _primary_key_order
2186     ds.last(*a, &block)
2187   else
2188     super
2189   end
2190 end
model() click to toggle source

The model class associated with this dataset

Artist.dataset.model # => Artist
     # File lib/sequel/model/base.rb
2148 def model
2149   @opts[:model]
2150 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
2200 def paged_each(*a, &block)
2201   if ds = _primary_key_order
2202     ds.paged_each(*a, &block)
2203   else
2204     super
2205   end
2206 end
to_hash(*a) click to toggle source

Alias of as_hash for backwards compatibility.

     # File lib/sequel/model/base.rb
2226 def to_hash(*a)
2227   as_hash(*a)
2228 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
2240 def with_pk(pk)
2241   if pk && (loader = _with_pk_loader)
2242     loader.first(*pk)
2243   else
2244     first(model.qualified_primary_key_hash(pk))
2245   end
2246 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
2250 def with_pk!(pk)
2251   with_pk(pk) || raise(NoMatchingRow.new(self))
2252 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
2258 def _force_primary_key_order
2259   cached_dataset(:_pk_order_ds){order(*model.primary_key)}
2260 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
2264 def _primary_key_order
2265   if @opts[:order].nil? && model && model.primary_key
2266     _force_primary_key_order
2267   end
2268 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
2271 def _with_pk_loader
2272   cached_placeholder_literalizer(:_with_pk_loader) do |pl|
2273     table = model.table_name
2274     cond = case primary_key = model.primary_key
2275     when Array
2276       primary_key.map{|key| [SQL::QualifiedIdentifier.new(table, key), pl.arg]}
2277     when Symbol
2278       {SQL::QualifiedIdentifier.new(table, primary_key)=>pl.arg}
2279     else
2280       raise(Error, "#{model} does not have a primary key")
2281     end
2282 
2283     where(cond).limit(1)
2284   end
2285 end
non_sql_option?(key) click to toggle source
Calls superclass method
     # File lib/sequel/model/base.rb
2287 def non_sql_option?(key)
2288   super || key == :model
2289 end