module Sequel::Plugins::SingleTableInheritance::ClassMethods

Attributes

The base dataset for STI, to which filters are added to get only the models for the specific STI subclass.

The column name holding the STI key for this model

Array holding keys for all subclasses of this class, used for the dataset filter in subclasses. Nil in the main class.

sti_key_chooser [R]

A proc which returns the value to use for new instances. This defaults to a lookup in the key map.

sti_key_map [R]

A hash/proc with class keys and column value values, mapping the class to a particular value given to the sti_key column. Used to set the column value when creating objects, and for the filter when retrieving objects in subclasses.

sti_model_map [R]

A hash/proc with column value keys and class values, mapping the value of the sti_key column to the appropriate class to use.

Public Instance Methods

freeze ()

Source

    # File lib/sequel/plugins/single_table_inheritance.rb
164 def freeze
165   @sti_key_array.freeze if @sti_key_array
166   @sti_key_map.freeze if @sti_key_map.is_a?(Hash)
167   @sti_model_map.freeze if @sti_model_map.is_a?(Hash)
168 
169   super
170 end

Freeze STI information when freezing model class. Note that because of how STI works, you should not freeze an STI subclass until after all subclasses of it have been created.

Calls superclass method

sti_class_from_sti_key (key)

Source

    # File lib/sequel/plugins/single_table_inheritance.rb
179 def sti_class_from_sti_key(key)
180   sti_class(sti_model_map[key])
181 end

Return the sti class based on one of the keys from sti_model_map.

sti_load (r)

Source

    # File lib/sequel/plugins/single_table_inheritance.rb
174 def sti_load(r)
175   sti_class_from_sti_key(r[sti_key]).call(r)
176 end

Return an instance of the class specified by sti_key, used by the row_proc.

sti_subclass_added (key)

Source

    # File lib/sequel/plugins/single_table_inheritance.rb
185 def sti_subclass_added(key)
186   if sti_key_array
187     key_array = Array(key)
188     Sequel.synchronize{sti_key_array.push(*key_array)}
189     superclass.sti_subclass_added(key)
190   end
191 end

Make sure that all subclasses of the parent class correctly include keys for all of their descendant classes.

Private Instance Methods

dataset_extend (mod, opts=OPTS)

Source

    # File lib/sequel/plugins/single_table_inheritance.rb
197 def dataset_extend(mod, opts=OPTS)
198   @sti_dataset = @sti_dataset.with_extend(mod)
199   super
200 end

Extend the sti dataset with the module when extending the main dataset.

Calls superclass method

inherited (subclass)

Source

    # File lib/sequel/plugins/single_table_inheritance.rb
204 def inherited(subclass)
205   super
206   key = Array(sti_key_map[subclass]).dup
207   sti_subclass_added(key)
208   rp = dataset.row_proc
209   subclass.set_dataset(sti_subclass_dataset(key), :inherited=>true)
210   subclass.instance_exec do
211     @dataset = @dataset.with_row_proc(rp)
212     @sti_key_array = key
213     self.simple_table = nil
214   end
215 end

Copy the necessary attributes to the subclasses, and filter the subclass’s dataset based on the sti_key_map entry for the class.

Calls superclass method

set_dataset_row_proc (ds)

Source

    # File lib/sequel/plugins/single_table_inheritance.rb
219 def set_dataset_row_proc(ds)
220   if @dataset
221     ds.with_row_proc(@dataset.row_proc)
222   else
223     super
224   end
225 end

If calling set_dataset manually, make sure to set the dataset row proc to one that handles inheritance correctly.

Calls superclass method

sti_class (v)

Source

    # File lib/sequel/plugins/single_table_inheritance.rb
234 def sti_class(v)
235   case v
236   when String, Symbol
237     begin
238       klass = constantize(v)
239       if Class === klass && @sti_root_class >= klass
240         klass
241       else
242         @sti_root_class
243       end
244     rescue
245       self
246     end
247   when nil
248     self
249   when Class
250     v
251   else
252     raise(Error, "Invalid class type used: #{v.inspect}")
253   end
254 end

Return a class object. If a class is given, return it directly. Treat strings and symbols as class names. If nil is given or an invalid class name string or symbol is used, return self. If the class is valid but is not a subclass of the class that loaded the single_table_inheritance plugin, use the class that loaded the plugin. Raise an error for other types.

sti_subclass_dataset (key)

Source

    # File lib/sequel/plugins/single_table_inheritance.rb
258 def sti_subclass_dataset(key)
259   sti_dataset.where(SQL::QualifiedIdentifier.new(sti_dataset.first_source_alias, sti_key)=>Sequel.delay{Sequel.synchronize{key}})
260 end

Use the given dataset for the subclass, with key being the allowed values for the sti_kind field.