module Sequel::Model::DatasetMethods

DatasetMethods contains methods that all model datasets have.

Public Instance Methods

Source

     # File lib/sequel/model/base.rb
2193 def [](*args)
2194   if args.length == 1 && (i = args[0]) && i.is_a?(Integer)
2195     with_pk(i)
2196   else
2197     super
2198   end
2199 end

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

as_hash (key_column=nil, value_column=nil, opts=OPTS)

Source

     # File lib/sequel/model/base.rb
2253 def as_hash(key_column=nil, value_column=nil, opts=OPTS)
2254   if key_column
2255     super
2256   else
2257     raise(Sequel::Error, "No primary key for model") unless model && (pk = model.primary_key)
2258     super(pk, value_column, opts) 
2259   end
2260 end

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

destroy ()

Source

     # File lib/sequel/model/base.rb
2210 def destroy
2211   @db.transaction(:server=>opts[:server], :skip_transaction=>model.use_transactions == false) do
2212     all(&:destroy).length
2213   end
2214 end

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)
# ...

last (*a, &block)

Source

     # File lib/sequel/model/base.rb
2221 def last(*a, &block)
2222   if ds = _primary_key_order
2223     ds.last(*a, &block)
2224   else
2225     super
2226   end
2227 end

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

model ()

Source

     # File lib/sequel/model/base.rb
2185 def model
2186   @opts[:model]
2187 end

The model class associated with this dataset

Artist.dataset.model # => Artist

paged_each (*a, &block)

Source

     # File lib/sequel/model/base.rb
2237 def paged_each(*a, &block)
2238   if ds = _primary_key_order
2239     ds.paged_each(*a, &block)
2240   else
2241     super
2242   end
2243 end

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

to_hash (*a)

Source

     # File lib/sequel/model/base.rb
2263 def to_hash(*a)
2264   as_hash(*a)
2265 end

Alias of as_hash for backwards compatibility.

with_pk (pk)

Source

     # File lib/sequel/model/base.rb
2277 def with_pk(pk)
2278   if pk && (loader = _with_pk_loader)
2279     loader.first(*pk)
2280   else
2281     first(model.qualified_primary_key_hash(pk))
2282   end
2283 end

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

with_pk! (pk)

Source

     # File lib/sequel/model/base.rb
2287 def with_pk!(pk)
2288   with_pk(pk) || raise(NoMatchingRow.new(self))
2289 end

Same as with_pk, but raises NoMatchingRow instead of returning nil if no row matches.

Private Instance Methods

_force_primary_key_order ()

Source

     # File lib/sequel/model/base.rb
2295 def _force_primary_key_order
2296   cached_dataset(:_pk_order_ds){order(*unambiguous_primary_key)}
2297 end

Return the dataset ordered by the model’s primary key. This should not be used if the model does not have a primary key.

_primary_key_order ()

Source

     # File lib/sequel/model/base.rb
2301 def _primary_key_order
2302   if @opts[:order].nil? && model && model.primary_key
2303     _force_primary_key_order
2304   end
2305 end

If the dataset is not already ordered, and the model has a primary key, return a clone ordered by the primary key.

_with_pk_loader ()

Source

     # File lib/sequel/model/base.rb
2308 def _with_pk_loader
2309   cached_placeholder_literalizer(:_with_pk_loader) do |pl|
2310     table = model.table_name
2311     cond = case primary_key = model.primary_key
2312     when Array
2313       primary_key.map{|key| [SQL::QualifiedIdentifier.new(table, key), pl.arg]}
2314     when Symbol
2315       {SQL::QualifiedIdentifier.new(table, primary_key)=>pl.arg}
2316     else
2317       raise(Error, "#{model} does not have a primary key")
2318     end
2319 
2320     where(cond).limit(1)
2321   end
2322 end

A cached placeholder literalizer, if one exists for the current dataset.

non_sql_option? (key)

Source

     # File lib/sequel/model/base.rb
2333 def non_sql_option?(key)
2334   super || key == :model
2335 end

Calls superclass method

unambiguous_primary_key ()

Source

     # File lib/sequel/model/base.rb
2325 def unambiguous_primary_key
2326   if joined_dataset?
2327     model.qualified_primary_key
2328   else
2329     model.primary_key
2330   end
2331 end

The primary key for the dataset’s model, qualified if the dataset is joined.