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
2095 def [](*args)
2096   if args.length == 1 && (i = args[0]) && i.is_a?(Integer)
2097     with_pk(i)
2098   else
2099     super
2100   end
2101 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
2154 def as_hash(key_column=nil, value_column=nil, opts=OPTS)
2155   if key_column
2156     super
2157   else
2158     raise(Sequel::Error, "No primary key for model") unless model && (pk = model.primary_key)
2159     super(pk, value_column, opts) 
2160   end
2161 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
2112 def destroy
2113   pr = proc{all(&:destroy).length}
2114   model.use_transactions ? @db.transaction(:server=>opts[:server], &pr) : pr.call
2115 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
2122 def last(*a, &block)
2123   if ds = _primary_key_order
2124     ds.last(*a, &block)
2125   else
2126     super
2127   end
2128 end
model() click to toggle source

The model class associated with this dataset

Artist.dataset.model # => Artist
     # File lib/sequel/model/base.rb
2087 def model
2088   @opts[:model]
2089 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
2138 def paged_each(*a, &block)
2139   if ds = _primary_key_order
2140     ds.paged_each(*a, &block)
2141   else
2142     super
2143   end
2144 end
to_hash(*a) click to toggle source

Alias of as_hash for backwards compatibility.

     # File lib/sequel/model/base.rb
2164 def to_hash(*a)
2165   as_hash(*a)
2166 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
2178 def with_pk(pk)
2179   if pk && (loader = _with_pk_loader)
2180     loader.first(*pk)
2181   else
2182     first(model.qualified_primary_key_hash(pk))
2183   end
2184 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
2188 def with_pk!(pk)
2189   with_pk(pk) || raise(NoMatchingRow.new(self))
2190 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
2196 def _primary_key_order
2197   if @opts[:order].nil? && model && (pk = model.primary_key)
2198     cached_dataset(:_pk_order_ds){order(*pk)}
2199   end
2200 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
2203 def _with_pk_loader
2204   cached_placeholder_literalizer(:_with_pk_loader) do |pl|
2205     table = model.table_name
2206     cond = case primary_key = model.primary_key
2207     when Array
2208       primary_key.map{|key| [SQL::QualifiedIdentifier.new(table, key), pl.arg]}
2209     when Symbol
2210       {SQL::QualifiedIdentifier.new(table, primary_key)=>pl.arg}
2211     else
2212       raise(Error, "#{model} does not have a primary key")
2213     end
2214 
2215     where(cond).limit(1)
2216   end
2217 end
non_sql_option?(key) click to toggle source
Calls superclass method
     # File lib/sequel/model/base.rb
2219 def non_sql_option?(key)
2220   super || key == :model
2221 end