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
2101 def [](*args)
2102   if args.length == 1 && (i = args[0]) && i.is_a?(Integer)
2103     with_pk(i)
2104   else
2105     super
2106   end
2107 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
2160 def as_hash(key_column=nil, value_column=nil, opts=OPTS)
2161   if key_column
2162     super
2163   else
2164     raise(Sequel::Error, "No primary key for model") unless model && (pk = model.primary_key)
2165     super(pk, value_column, opts) 
2166   end
2167 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
2118 def destroy
2119   pr = proc{all(&:destroy).length}
2120   model.use_transactions ? @db.transaction(:server=>opts[:server], &pr) : pr.call
2121 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
2128 def last(*a, &block)
2129   if ds = _primary_key_order
2130     ds.last(*a, &block)
2131   else
2132     super
2133   end
2134 end
model() click to toggle source

The model class associated with this dataset

Artist.dataset.model # => Artist
     # File lib/sequel/model/base.rb
2093 def model
2094   @opts[:model]
2095 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
2144 def paged_each(*a, &block)
2145   if ds = _primary_key_order
2146     ds.paged_each(*a, &block)
2147   else
2148     super
2149   end
2150 end
to_hash(*a) click to toggle source

Alias of as_hash for backwards compatibility.

     # File lib/sequel/model/base.rb
2170 def to_hash(*a)
2171   as_hash(*a)
2172 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
2184 def with_pk(pk)
2185   if pk && (loader = _with_pk_loader)
2186     loader.first(*pk)
2187   else
2188     first(model.qualified_primary_key_hash(pk))
2189   end
2190 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
2194 def with_pk!(pk)
2195   with_pk(pk) || raise(NoMatchingRow.new(self))
2196 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
2202 def _primary_key_order
2203   if @opts[:order].nil? && model && (pk = model.primary_key)
2204     cached_dataset(:_pk_order_ds){order(*pk)}
2205   end
2206 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
2209 def _with_pk_loader
2210   cached_placeholder_literalizer(:_with_pk_loader) do |pl|
2211     table = model.table_name
2212     cond = case primary_key = model.primary_key
2213     when Array
2214       primary_key.map{|key| [SQL::QualifiedIdentifier.new(table, key), pl.arg]}
2215     when Symbol
2216       {SQL::QualifiedIdentifier.new(table, primary_key)=>pl.arg}
2217     else
2218       raise(Error, "#{model} does not have a primary key")
2219     end
2220 
2221     where(cond).limit(1)
2222   end
2223 end
non_sql_option?(key) click to toggle source
Calls superclass method
     # File lib/sequel/model/base.rb
2225 def non_sql_option?(key)
2226   super || key == :model
2227 end