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
2037 def [](*args)
2038   if args.length == 1 && (i = args[0]) && i.is_a?(Integer)
2039     with_pk(i)
2040   else
2041     super
2042   end
2043 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
2096 def as_hash(key_column=nil, value_column=nil, opts=OPTS)
2097   if key_column
2098     super
2099   else
2100     raise(Sequel::Error, "No primary key for model") unless model && (pk = model.primary_key)
2101     super(pk, value_column, opts) 
2102   end
2103 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
2054 def destroy
2055   pr = proc{all(&:destroy).length}
2056   model.use_transactions ? @db.transaction(:server=>opts[:server], &pr) : pr.call
2057 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
2064 def last(*a, &block)
2065   if ds = _primary_key_order
2066     ds.last(*a, &block)
2067   else
2068     super
2069   end
2070 end
model() click to toggle source

The model class associated with this dataset

Artist.dataset.model # => Artist
     # File lib/sequel/model/base.rb
2029 def model
2030   @opts[:model]
2031 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
2080 def paged_each(*a, &block)
2081   if ds = _primary_key_order
2082     ds.paged_each(*a, &block)
2083   else
2084     super
2085   end
2086 end
to_hash(*a) click to toggle source

Alias of as_hash for backwards compatibility.

     # File lib/sequel/model/base.rb
2106 def to_hash(*a)
2107   as_hash(*a)
2108 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
2120 def with_pk(pk)
2121   if pk && (loader = _with_pk_loader)
2122     loader.first(*pk)
2123   else
2124     first(model.qualified_primary_key_hash(pk))
2125   end
2126 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
2130 def with_pk!(pk)
2131   with_pk(pk) || raise(NoMatchingRow.new(self))
2132 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
2138 def _primary_key_order
2139   if @opts[:order].nil? && model && (pk = model.primary_key)
2140     cached_dataset(:_pk_order_ds){order(*pk)}
2141   end
2142 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
2145 def _with_pk_loader
2146   cached_placeholder_literalizer(:_with_pk_loader) do |pl|
2147     table = model.table_name
2148     cond = case primary_key = model.primary_key
2149     when Array
2150       primary_key.map{|key| [SQL::QualifiedIdentifier.new(table, key), pl.arg]}
2151     when Symbol
2152       {SQL::QualifiedIdentifier.new(table, primary_key)=>pl.arg}
2153     else
2154       raise(Error, "#{model} does not have a primary key")
2155     end
2156 
2157     where(cond).limit(1)
2158   end
2159 end
non_sql_option?(key) click to toggle source
Calls superclass method
     # File lib/sequel/model/base.rb
2161 def non_sql_option?(key)
2162   super || key == :model
2163 end