module Sequel::Model::DatasetMethods

DatasetMethods contains methods that all model datasets have.

Public Instance Methods

Source

     # File lib/sequel/model/base.rb
2279 def [](*args)
2280   if args.length == 1 && (i = args[0]) && i.is_a?(Integer)
2281     with_pk(i)
2282   else
2283     super
2284   end
2285 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
2339 def as_hash(key_column=nil, value_column=nil, opts=OPTS)
2340   if key_column
2341     super
2342   else
2343     raise(Sequel::Error, "No primary key for model") unless model && (pk = model.primary_key)
2344     super(pk, value_column, opts) 
2345   end
2346 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
2296 def destroy
2297   @db.transaction(:server=>opts[:server], :skip_transaction=>model.use_transactions == false) do
2298     all(&:destroy).length
2299   end
2300 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
2307 def last(*a, &block)
2308   if ds = _primary_key_order
2309     ds.last(*a, &block)
2310   else
2311     super
2312   end
2313 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
2271 def model
2272   @opts[:model]
2273 end

The model class associated with this dataset

Artist.dataset.model # => Artist

paged_each (*a, &block)

Source

     # File lib/sequel/model/base.rb
2323 def paged_each(*a, &block)
2324   if ds = _primary_key_order
2325     ds.paged_each(*a, &block)
2326   else
2327     super
2328   end
2329 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
2349 def to_hash(*a)
2350   as_hash(*a)
2351 end

Alias of as_hash for backwards compatibility.

with_pk (pk)

Source

     # File lib/sequel/model/base.rb
2363 def with_pk(pk)
2364   if pk && (loader = _with_pk_loader)
2365     loader.first(*pk)
2366   else
2367     first(model.qualified_primary_key_hash(pk))
2368   end
2369 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
2373 def with_pk!(pk)
2374   with_pk(pk) || raise(NoMatchingRow.new(self))
2375 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
2381 def _force_primary_key_order
2382   cached_dataset(:_pk_order_ds){order(*unambiguous_primary_key)}
2383 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
2387 def _primary_key_order
2388   if @opts[:order].nil? && model && model.primary_key
2389     _force_primary_key_order
2390   end
2391 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
2394 def _with_pk_loader
2395   cached_placeholder_literalizer(:_with_pk_loader) do |pl|
2396     table = model.table_name
2397     cond = case primary_key = model.primary_key
2398     when Array
2399       primary_key.map{|key| [SQL::QualifiedIdentifier.new(table, key), pl.arg]}
2400     when Symbol
2401       {SQL::QualifiedIdentifier.new(table, primary_key)=>pl.arg}
2402     else
2403       raise(Error, "#{model} does not have a primary key")
2404     end
2405 
2406     where(cond).limit(1)
2407   end
2408 end

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

non_sql_option? (key)

Source

     # File lib/sequel/model/base.rb
2419 def non_sql_option?(key)
2420   super || key == :model
2421 end

Calls superclass method

unambiguous_primary_key ()

Source

     # File lib/sequel/model/base.rb
2411 def unambiguous_primary_key
2412   if joined_dataset?
2413     model.qualified_primary_key
2414   else
2415     model.primary_key
2416   end
2417 end

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