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
2088 def [](*args)
2089   if args.length == 1 && (i = args[0]) && i.is_a?(Integer)
2090     with_pk(i)
2091   else
2092     super
2093   end
2094 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
2147 def as_hash(key_column=nil, value_column=nil, opts=OPTS)
2148   if key_column
2149     super
2150   else
2151     raise(Sequel::Error, "No primary key for model") unless model && (pk = model.primary_key)
2152     super(pk, value_column, opts) 
2153   end
2154 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
2105 def destroy
2106   pr = proc{all(&:destroy).length}
2107   model.use_transactions ? @db.transaction(:server=>opts[:server], &pr) : pr.call
2108 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
2115 def last(*a, &block)
2116   if ds = _primary_key_order
2117     ds.last(*a, &block)
2118   else
2119     super
2120   end
2121 end
model() click to toggle source

The model class associated with this dataset

Artist.dataset.model # => Artist
     # File lib/sequel/model/base.rb
2080 def model
2081   @opts[:model]
2082 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
2131 def paged_each(*a, &block)
2132   if ds = _primary_key_order
2133     ds.paged_each(*a, &block)
2134   else
2135     super
2136   end
2137 end
to_hash(*a) click to toggle source

Alias of as_hash for backwards compatibility.

     # File lib/sequel/model/base.rb
2157 def to_hash(*a)
2158   as_hash(*a)
2159 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
2171 def with_pk(pk)
2172   if pk && (loader = _with_pk_loader)
2173     loader.first(*pk)
2174   else
2175     first(model.qualified_primary_key_hash(pk))
2176   end
2177 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
2181 def with_pk!(pk)
2182   with_pk(pk) || raise(NoMatchingRow.new(self))
2183 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
2189 def _primary_key_order
2190   if @opts[:order].nil? && model && (pk = model.primary_key)
2191     cached_dataset(:_pk_order_ds){order(*pk)}
2192   end
2193 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
2196 def _with_pk_loader
2197   cached_placeholder_literalizer(:_with_pk_loader) do |pl|
2198     table = model.table_name
2199     cond = case primary_key = model.primary_key
2200     when Array
2201       primary_key.map{|key| [SQL::QualifiedIdentifier.new(table, key), pl.arg]}
2202     when Symbol
2203       {SQL::QualifiedIdentifier.new(table, primary_key)=>pl.arg}
2204     else
2205       raise(Error, "#{model} does not have a primary key")
2206     end
2207 
2208     where(cond).limit(1)
2209   end
2210 end
non_sql_option?(key) click to toggle source
Calls superclass method
     # File lib/sequel/model/base.rb
2212 def non_sql_option?(key)
2213   super || key == :model
2214 end