module Sequel::Model::DatasetMethods

DatasetMethods contains methods that all model datasets have.

Public Instance Methods

Source

     # File lib/sequel/model/base.rb
2287 def [](*args)
2288   if args.length == 1 && (i = args[0]) && i.is_a?(Integer)
2289     with_pk(i)
2290   else
2291     super
2292   end
2293 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
2347 def as_hash(key_column=nil, value_column=nil, opts=OPTS)
2348   if key_column
2349     super
2350   else
2351     raise(Sequel::Error, "No primary key for model") unless model && (pk = model.primary_key)
2352     super(pk, value_column, opts) 
2353   end
2354 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
2304 def destroy
2305   @db.transaction(:server=>opts[:server], :skip_transaction=>model.use_transactions == false) do
2306     all(&:destroy).length
2307   end
2308 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
2315 def last(*a, &block)
2316   if ds = _primary_key_order
2317     ds.last(*a, &block)
2318   else
2319     super
2320   end
2321 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
2279 def model
2280   @opts[:model]
2281 end

The model class associated with this dataset

Artist.dataset.model # => Artist

paged_each (*a, &block)

Source

     # File lib/sequel/model/base.rb
2331 def paged_each(*a, &block)
2332   if ds = _primary_key_order
2333     ds.paged_each(*a, &block)
2334   else
2335     super
2336   end
2337 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
2357 def to_hash(*a)
2358   as_hash(*a)
2359 end

Alias of as_hash for backwards compatibility.

with_pk (pk)

Source

     # File lib/sequel/model/base.rb
2371 def with_pk(pk)
2372   if pk && (loader = _with_pk_loader)
2373     loader.first(*pk)
2374   else
2375     first(model.qualified_primary_key_hash(pk))
2376   end
2377 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
2381 def with_pk!(pk)
2382   with_pk(pk) || raise(NoMatchingRow.new(self))
2383 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
2389 def _force_primary_key_order
2390   cached_dataset(:_pk_order_ds){order(*unambiguous_primary_key)}
2391 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
2395 def _primary_key_order
2396   if @opts[:order].nil? && model && model.primary_key
2397     _force_primary_key_order
2398   end
2399 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
2402 def _with_pk_loader
2403   cached_placeholder_literalizer(:_with_pk_loader) do |pl|
2404     table = model.table_name
2405     cond = case primary_key = model.primary_key
2406     when Array
2407       primary_key.map{|key| [SQL::QualifiedIdentifier.new(table, key), pl.arg]}
2408     when Symbol
2409       {SQL::QualifiedIdentifier.new(table, primary_key)=>pl.arg}
2410     else
2411       raise(Error, "#{model} does not have a primary key")
2412     end
2413 
2414     where(cond).limit(1)
2415   end
2416 end

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

non_sql_option? (key)

Source

     # File lib/sequel/model/base.rb
2427 def non_sql_option?(key)
2428   super || key == :model
2429 end

Calls superclass method

unambiguous_primary_key ()

Source

     # File lib/sequel/model/base.rb
2419 def unambiguous_primary_key
2420   if joined_dataset?
2421     model.qualified_primary_key
2422   else
2423     model.primary_key
2424   end
2425 end

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