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
2108 def [](*args)
2109   if args.length == 1 && (i = args[0]) && i.is_a?(Integer)
2110     with_pk(i)
2111   else
2112     super
2113   end
2114 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
2167 def as_hash(key_column=nil, value_column=nil, opts=OPTS)
2168   if key_column
2169     super
2170   else
2171     raise(Sequel::Error, "No primary key for model") unless model && (pk = model.primary_key)
2172     super(pk, value_column, opts) 
2173   end
2174 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
2125 def destroy
2126   pr = proc{all(&:destroy).length}
2127   model.use_transactions ? @db.transaction(:server=>opts[:server], &pr) : pr.call
2128 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
2135 def last(*a, &block)
2136   if ds = _primary_key_order
2137     ds.last(*a, &block)
2138   else
2139     super
2140   end
2141 end
model() click to toggle source

The model class associated with this dataset

Artist.dataset.model # => Artist
     # File lib/sequel/model/base.rb
2100 def model
2101   @opts[:model]
2102 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
2151 def paged_each(*a, &block)
2152   if ds = _primary_key_order
2153     ds.paged_each(*a, &block)
2154   else
2155     super
2156   end
2157 end
to_hash(*a) click to toggle source

Alias of as_hash for backwards compatibility.

     # File lib/sequel/model/base.rb
2177 def to_hash(*a)
2178   as_hash(*a)
2179 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
2191 def with_pk(pk)
2192   if pk && (loader = _with_pk_loader)
2193     loader.first(*pk)
2194   else
2195     first(model.qualified_primary_key_hash(pk))
2196   end
2197 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
2201 def with_pk!(pk)
2202   with_pk(pk) || raise(NoMatchingRow.new(self))
2203 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
2209 def _primary_key_order
2210   if @opts[:order].nil? && model && (pk = model.primary_key)
2211     cached_dataset(:_pk_order_ds){order(*pk)}
2212   end
2213 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
2216 def _with_pk_loader
2217   cached_placeholder_literalizer(:_with_pk_loader) do |pl|
2218     table = model.table_name
2219     cond = case primary_key = model.primary_key
2220     when Array
2221       primary_key.map{|key| [SQL::QualifiedIdentifier.new(table, key), pl.arg]}
2222     when Symbol
2223       {SQL::QualifiedIdentifier.new(table, primary_key)=>pl.arg}
2224     else
2225       raise(Error, "#{model} does not have a primary key")
2226     end
2227 
2228     where(cond).limit(1)
2229   end
2230 end
non_sql_option?(key) click to toggle source
Calls superclass method
     # File lib/sequel/model/base.rb
2232 def non_sql_option?(key)
2233   super || key == :model
2234 end