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
2125 def [](*args)
2126   if args.length == 1 && (i = args[0]) && i.is_a?(Integer)
2127     with_pk(i)
2128   else
2129     super
2130   end
2131 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
2184 def as_hash(key_column=nil, value_column=nil, opts=OPTS)
2185   if key_column
2186     super
2187   else
2188     raise(Sequel::Error, "No primary key for model") unless model && (pk = model.primary_key)
2189     super(pk, value_column, opts) 
2190   end
2191 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
2142 def destroy
2143   pr = proc{all(&:destroy).length}
2144   model.use_transactions ? @db.transaction(:server=>opts[:server], &pr) : pr.call
2145 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
2152 def last(*a, &block)
2153   if ds = _primary_key_order
2154     ds.last(*a, &block)
2155   else
2156     super
2157   end
2158 end
model() click to toggle source

The model class associated with this dataset

Artist.dataset.model # => Artist
     # File lib/sequel/model/base.rb
2117 def model
2118   @opts[:model]
2119 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
2168 def paged_each(*a, &block)
2169   if ds = _primary_key_order
2170     ds.paged_each(*a, &block)
2171   else
2172     super
2173   end
2174 end
to_hash(*a) click to toggle source

Alias of as_hash for backwards compatibility.

     # File lib/sequel/model/base.rb
2194 def to_hash(*a)
2195   as_hash(*a)
2196 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
2208 def with_pk(pk)
2209   if pk && (loader = _with_pk_loader)
2210     loader.first(*pk)
2211   else
2212     first(model.qualified_primary_key_hash(pk))
2213   end
2214 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
2218 def with_pk!(pk)
2219   with_pk(pk) || raise(NoMatchingRow.new(self))
2220 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
2226 def _primary_key_order
2227   if @opts[:order].nil? && model && (pk = model.primary_key)
2228     cached_dataset(:_pk_order_ds){order(*pk)}
2229   end
2230 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
2233 def _with_pk_loader
2234   cached_placeholder_literalizer(:_with_pk_loader) do |pl|
2235     table = model.table_name
2236     cond = case primary_key = model.primary_key
2237     when Array
2238       primary_key.map{|key| [SQL::QualifiedIdentifier.new(table, key), pl.arg]}
2239     when Symbol
2240       {SQL::QualifiedIdentifier.new(table, primary_key)=>pl.arg}
2241     else
2242       raise(Error, "#{model} does not have a primary key")
2243     end
2244 
2245     where(cond).limit(1)
2246   end
2247 end
non_sql_option?(key) click to toggle source
Calls superclass method
     # File lib/sequel/model/base.rb
2249 def non_sql_option?(key)
2250   super || key == :model
2251 end