Class Sequel::Model::Associations::AssociationReflection
In: lib/sequel/model/associations.rb
Parent: Hash

AssociationReflection is a Hash subclass that keeps information on Sequel::Model associations. It provides methods to reduce internal code duplication. It should not be instantiated by the user.

Methods

Included Modules

Sequel::Inflections

Constants

ASSOCIATION_DATASET_PROC = proc{|r| r.association_dataset_for(self)}
FINALIZE_SETTINGS = { :associated_class=>:class, :associated_dataset=>:_dataset, :associated_eager_dataset=>:associated_eager_dataset, :eager_limit_strategy=>:_eager_limit_strategy, :filter_by_associations_conditions_dataset=>:filter_by_associations_conditions_dataset, :placeholder_loader=>:placeholder_loader, :predicate_key=>:predicate_key, :predicate_keys=>:predicate_keys, :reciprocal=>:reciprocal, }.freeze   Map of methods to cache keys used for finalizing associations.

Public Instance methods

Name symbol for the _add internal association method

[Source]

    # File lib/sequel/model/associations.rb, line 36
36:         def _add_method
37:           self[:_add_method]
38:         end

Name symbol for the _remove_all internal association method

[Source]

    # File lib/sequel/model/associations.rb, line 41
41:         def _remove_all_method
42:           self[:_remove_all_method]
43:         end

Name symbol for the _remove internal association method

[Source]

    # File lib/sequel/model/associations.rb, line 46
46:         def _remove_method
47:           self[:_remove_method]
48:         end

Name symbol for the _setter association method

[Source]

    # File lib/sequel/model/associations.rb, line 51
51:         def _setter_method
52:           self[:_setter_method]
53:         end

Name symbol for the add association method

[Source]

    # File lib/sequel/model/associations.rb, line 56
56:         def add_method
57:           self[:add_method]
58:         end

Apply all non-instance specific changes to the given dataset and return it.

[Source]

    # File lib/sequel/model/associations.rb, line 84
84:         def apply_dataset_changes(ds)
85:           ds = ds.with_extend(AssociationDatasetMethods).clone(:association_reflection => self)
86:           if exts = self[:reverse_extend]
87:             ds = ds.with_extend(*exts)
88:           end
89:           ds = ds.select(*select) if select
90:           if c = self[:conditions]
91:             ds = (c.is_a?(Array) && !Sequel.condition_specifier?(c)) ? ds.where(*c) : ds.where(c)
92:           end
93:           ds = ds.order(*self[:order]) if self[:order]
94:           ds = ds.limit(*self[:limit]) if self[:limit]
95:           ds = ds.limit(1).skip_limit_check if limit_to_single_row?
96:           ds = ds.eager(self[:eager]) if self[:eager]
97:           ds = ds.distinct if self[:distinct]
98:           ds
99:         end

Use DISTINCT ON and ORDER BY clauses to limit the results to the first record with matching keys.

[Source]

     # File lib/sequel/model/associations.rb, line 138
138:         def apply_distinct_on_eager_limit_strategy(ds)
139:           keys = predicate_key
140:           ds.distinct(*keys).order_prepend(*keys)
141:         end

Apply all non-instance specific changes and the eager_block option to the given dataset and return it.

[Source]

     # File lib/sequel/model/associations.rb, line 103
103:         def apply_eager_dataset_changes(ds)
104:           ds = apply_dataset_changes(ds)
105:           if block = self[:eager_block]
106:             ds = block.call(ds)
107:           end
108:           ds
109:         end

Apply the eager graph limit strategy to the dataset to graph into the current dataset, or return the dataset unmodified if no SQL limit strategy is needed.

[Source]

     # File lib/sequel/model/associations.rb, line 113
113:         def apply_eager_graph_limit_strategy(strategy, ds)
114:           case strategy
115:           when :distinct_on
116:             apply_distinct_on_eager_limit_strategy(ds.order_prepend(*self[:order]))
117:           when :window_function
118:             apply_window_function_eager_limit_strategy(ds.order_prepend(*self[:order])).select(*ds.columns)
119:           else
120:             ds
121:           end
122:         end

Apply an eager limit strategy to the dataset, or return the dataset unmodified if it doesn‘t need an eager limit strategy.

[Source]

     # File lib/sequel/model/associations.rb, line 126
126:         def apply_eager_limit_strategy(ds, strategy=eager_limit_strategy, limit_and_offset=limit_and_offset())
127:           case strategy
128:           when :distinct_on
129:             apply_distinct_on_eager_limit_strategy(ds)
130:           when :window_function
131:             apply_window_function_eager_limit_strategy(ds, limit_and_offset)
132:           else
133:             ds
134:           end
135:         end

If the ruby eager limit strategy is being used, slice the array using the slice range to return the object(s) at the correct offset/limit.

[Source]

     # File lib/sequel/model/associations.rb, line 164
164:         def apply_ruby_eager_limit_strategy(rows, limit_and_offset = limit_and_offset())
165:           name = self[:name]
166:           if returns_array?
167:             range = slice_range(limit_and_offset)
168:             rows.each{|o| o.associations[name] = o.associations[name][range] || []}
169:           elsif sr = slice_range(limit_and_offset)
170:             offset = sr.begin
171:             rows.each{|o| o.associations[name] = o.associations[name][offset]}
172:           end
173:         end

Use a window function to limit the results of the eager loading dataset.

[Source]

     # File lib/sequel/model/associations.rb, line 144
144:         def apply_window_function_eager_limit_strategy(ds, limit_and_offset=limit_and_offset())
145:           rn = ds.row_number_column 
146:           limit, offset = limit_and_offset
147:           ds = ds.unordered.select_append{|o| o.row_number.function.over(:partition=>predicate_key, :order=>ds.opts[:order]).as(rn)}.from_self
148:           ds = if !returns_array?
149:             ds.where(rn => offset ? offset+1 : 1)
150:           elsif offset
151:             offset += 1
152:             if limit
153:               ds.where(rn => (offset...(offset+limit))) 
154:             else
155:               ds.where{SQL::Identifier.new(rn) >= offset} 
156:             end
157:           else
158:             ds.where{SQL::Identifier.new(rn) <= limit} 
159:           end
160:         end

Whether the associations cache should use an array when storing the associated records during eager loading.

[Source]

     # File lib/sequel/model/associations.rb, line 177
177:         def assign_singular?
178:           !returns_array?
179:         end

The class associated to the current model class via this association

[Source]

    # File lib/sequel/model/associations.rb, line 66
66:         def associated_class
67:           cached_fetch(:class) do
68:             begin
69:               constantize(self[:class_name])
70:             rescue NameError => e
71:               raise NameError, "#{e.message} (this happened when attempting to find the associated class for #{inspect})", e.backtrace
72:             end
73:           end
74:         end

The dataset associated via this association, with the non-instance specific changes already applied. This will be a joined dataset if the association requires joining tables.

[Source]

    # File lib/sequel/model/associations.rb, line 79
79:         def associated_dataset
80:           cached_fetch(:_dataset){apply_dataset_changes(_associated_dataset)}
81:         end

Return an dataset that will load the appropriate associated objects for the given object using this association.

[Source]

     # File lib/sequel/model/associations.rb, line 214
214:         def association_dataset_for(object)
215:           condition = if can_have_associated_objects?(object)
216:             predicate_keys.zip(predicate_key_values(object))
217:           else
218:             false
219:           end
220: 
221:           associated_dataset.where(condition)
222:         end

Proc used to create the association dataset method.

[Source]

     # File lib/sequel/model/associations.rb, line 226
226:         def association_dataset_proc
227:           ASSOCIATION_DATASET_PROC
228:         end

Name symbol for association method, the same as the name of the association.

[Source]

    # File lib/sequel/model/associations.rb, line 61
61:         def association_method
62:           self[:name]
63:         end

Whether this association can have associated objects, given the current object. Should be false if obj cannot have associated objects because the necessary key columns are NULL.

[Source]

     # File lib/sequel/model/associations.rb, line 184
184:         def can_have_associated_objects?(obj)
185:           true
186:         end

Whether you are able to clone from the given association type to the current association type, true by default only if the types match.

[Source]

     # File lib/sequel/model/associations.rb, line 190
190:         def cloneable?(ref)
191:           ref[:type] == self[:type]
192:         end

Name symbol for the dataset association method

[Source]

     # File lib/sequel/model/associations.rb, line 195
195:         def dataset_method
196:           self[:dataset_method]
197:         end

Whether the dataset needs a primary key to function, true by default.

[Source]

     # File lib/sequel/model/associations.rb, line 200
200:         def dataset_need_primary_key?
201:           true
202:         end

Return the symbol used for the row number column if the window function eager limit strategy is being used, or nil otherwise.

[Source]

     # File lib/sequel/model/associations.rb, line 206
206:         def delete_row_number_column(ds=associated_dataset)
207:           if eager_limit_strategy == :window_function
208:             ds.row_number_column 
209:           end
210:         end

Whether to eagerly graph a lazy dataset, true by default. If this is false, the association won‘t respect the :eager_graph option when loading the association for a single record.

[Source]

     # File lib/sequel/model/associations.rb, line 333
333:         def eager_graph_lazy_dataset?
334:           true
335:         end

The eager_graph limit strategy to use for this dataset

[Source]

     # File lib/sequel/model/associations.rb, line 231
231:         def eager_graph_limit_strategy(strategy)
232:           if self[:limit] || !returns_array?
233:             strategy = strategy[self[:name]] if strategy.is_a?(Hash)
234:             case strategy
235:             when true
236:               true_eager_graph_limit_strategy
237:             when Symbol
238:               strategy
239:             else
240:               if returns_array? || offset
241:                 :ruby
242:               end
243:             end
244:           end
245:         end

The eager limit strategy to use for this dataset.

[Source]

     # File lib/sequel/model/associations.rb, line 248
248:         def eager_limit_strategy
249:           cached_fetch(:_eager_limit_strategy) do
250:             if self[:limit] || !returns_array?
251:               case s = cached_fetch(:eager_limit_strategy){default_eager_limit_strategy}
252:               when true
253:                 true_eager_limit_strategy
254:               else
255:                 s
256:               end
257:             end
258:           end
259:         end

Eager load the associated objects using the hash of eager options, yielding each row to the block.

[Source]

     # File lib/sequel/model/associations.rb, line 263
263:         def eager_load_results(eo, &block)
264:           rows = eo[:rows]
265:           initialize_association_cache(rows) unless eo[:initialize_rows] == false
266:           if eo[:id_map]
267:             ids = eo[:id_map].keys
268:             return ids if ids.empty?
269:           end
270:           strategy = eager_limit_strategy
271:           cascade = eo[:associations]
272:           eager_limit = nil
273: 
274:           if eo[:eager_block] || eo[:loader] == false
275:             ds = eager_loading_dataset(eo)
276: 
277:             strategy = ds.opts[:eager_limit_strategy] || strategy
278: 
279:             eager_limit =
280:               if el = ds.opts[:eager_limit]
281:                 raise Error, "The :eager_limit dataset option is not supported for associations returning a single record" unless returns_array?
282:                 strategy ||= true_eager_graph_limit_strategy
283:                 if el.is_a?(Array)
284:                   el
285:                 else
286:                   [el, nil]
287:                 end
288:               else
289:                 limit_and_offset
290:               end
291: 
292:             strategy = true_eager_graph_limit_strategy if strategy == :union
293:             # Correlated subqueries are not supported for regular eager loading
294:             strategy = :ruby if strategy == :correlated_subquery
295:             strategy = nil if strategy == :ruby && assign_singular?
296:             objects = apply_eager_limit_strategy(ds, strategy, eager_limit).all
297:           elsif strategy == :union
298:             objects = []
299:             ds = associated_dataset
300:             loader = union_eager_loader
301:             joiner = " UNION ALL "
302:             ids.each_slice(subqueries_per_union).each do |slice|
303:               objects.concat(ds.with_sql(slice.map{|k| loader.sql(*k)}.join(joiner)).to_a)
304:             end
305:             ds = ds.eager(cascade) if cascade
306:             ds.send(:post_load, objects)
307:           else
308:             loader = placeholder_eager_loader
309:             loader = loader.with_dataset{|dataset| dataset.eager(cascade)} if cascade
310:             objects = loader.all(ids)
311:           end
312: 
313:           objects.each(&block)
314:           if strategy == :ruby
315:             apply_ruby_eager_limit_strategy(rows, eager_limit || limit_and_offset)
316:           end
317:         end

The key to use for the key hash when eager loading

[Source]

     # File lib/sequel/model/associations.rb, line 320
320:         def eager_loader_key
321:           self[:eager_loader_key]
322:         end

By default associations do not need to select a key in an associated table to eagerly load.

[Source]

     # File lib/sequel/model/associations.rb, line 326
326:         def eager_loading_use_associated_key?
327:           false
328:         end

Whether additional conditions should be added when using the filter by associations support.

[Source]

     # File lib/sequel/model/associations.rb, line 339
339:         def filter_by_associations_add_conditions?
340:           self[:conditions] || self[:eager_block] || self[:limit]
341:         end

The expression to use for the additional conditions to be added for the filter by association support, when the association itself is filtered. Works by using a subquery to test that the objects passed also meet the association filter criteria.

[Source]

     # File lib/sequel/model/associations.rb, line 347
347:         def filter_by_associations_conditions_expression(obj)
348:           ds = filter_by_associations_conditions_dataset.where(filter_by_associations_conditions_subquery_conditions(obj))
349:           {filter_by_associations_conditions_key=>ds}
350:         end

Finalize the association by first attempting to populate the thread-safe cache, and then transfering the thread-safe cache value to the association itself, so that a mutex is not needed to get the value.

[Source]

     # File lib/sequel/model/associations.rb, line 355
355:         def finalize
356:           return unless cache = self[:cache]
357: 
358:           finalize_settings.each do |meth, key|
359:             next if has_key?(key)
360: 
361:             # Allow calling private methods to make sure caching is done appropriately
362:             send(meth)
363:             self[key] = cache.delete(key) if cache.has_key?(key)
364:           end
365: 
366:           nil
367:         end

[Source]

     # File lib/sequel/model/associations.rb, line 381
381:         def finalize_settings
382:           FINALIZE_SETTINGS
383:         end

Whether to handle silent modification failure when adding/removing associated records, false by default.

[Source]

     # File lib/sequel/model/associations.rb, line 387
387:         def handle_silent_modification_failure?
388:           false
389:         end

Initialize the associations cache for the current association for the given objects.

[Source]

     # File lib/sequel/model/associations.rb, line 392
392:         def initialize_association_cache(objects)
393:           name = self[:name]
394:           if assign_singular?
395:             objects.each{|object| object.associations[name] = nil}
396:           else
397:             objects.each{|object| object.associations[name] = []}
398:           end
399:         end

Show which type of reflection this is, and a guess at what code was used to create the association.

[Source]

     # File lib/sequel/model/associations.rb, line 403
403:         def inspect
404:           o = self[:orig_opts].dup
405:           o.delete(:class)
406:           o.delete(:class_name)
407:           o.delete(:block) unless o[:block]
408:           o[:class] = self[:orig_class] if self[:orig_class]
409: 
410:           "#<#{self.class} #{self[:model]}.#{self[:type]} #{self[:name].inspect}#{", #{o.inspect[1...-1]}" unless o.empty?}>"
411:         end

The limit and offset for this association (returned as a two element array).

[Source]

     # File lib/sequel/model/associations.rb, line 414
414:         def limit_and_offset
415:           if (v = self[:limit]).is_a?(Array)
416:             v
417:           else
418:             [v, nil]
419:           end
420:         end

Whether the associated object needs a primary key to be added/removed, false by default.

[Source]

     # File lib/sequel/model/associations.rb, line 424
424:         def need_associated_primary_key?
425:           false
426:         end

A placeholder literalizer that can be used to lazily load the association. If one can‘t be used, returns nil.

[Source]

     # File lib/sequel/model/associations.rb, line 430
430:         def placeholder_loader
431:           if use_placeholder_loader?
432:             cached_fetch(:placeholder_loader) do
433:               Sequel::Dataset::PlaceholderLiteralizer.loader(associated_dataset) do |pl, ds|
434:                 ds.where(Sequel.&(*predicate_keys.map{|k| SQL::BooleanExpression.new('=''=', k, pl.arg)}))
435:               end
436:             end
437:           end
438:         end

The values that predicate_keys should match for objects to be associated.

[Source]

     # File lib/sequel/model/associations.rb, line 446
446:         def predicate_key_values(object)
447:           predicate_key_methods.map{|k| object.get_column_value(k)}
448:         end

The keys to use for loading of the regular dataset, as an array.

[Source]

     # File lib/sequel/model/associations.rb, line 441
441:         def predicate_keys
442:           cached_fetch(:predicate_keys){Array(predicate_key)}
443:         end

Qualify col with the given table name.

[Source]

     # File lib/sequel/model/associations.rb, line 451
451:         def qualify(table, col)
452:           transform(col) do |k|
453:             case k
454:             when Symbol, SQL::Identifier
455:               SQL::QualifiedIdentifier.new(table, k)
456:             else
457:               Sequel::Qualifier.new(table).transform(k)
458:             end
459:           end
460:         end

Qualify col with the associated model‘s table name.

[Source]

     # File lib/sequel/model/associations.rb, line 463
463:         def qualify_assoc(col)
464:           qualify(associated_class.table_name, col)
465:         end

Qualify col with the current model‘s table name.

[Source]

     # File lib/sequel/model/associations.rb, line 468
468:         def qualify_cur(col)
469:           qualify(self[:model].table_name, col)
470:         end

Returns the reciprocal association variable, if one exists. The reciprocal association is the association in the associated class that is the opposite of the current association. For example, Album.many_to_one :artist and Artist.one_to_many :albums are reciprocal associations. This information is to populate reciprocal associations. For example, when you do this_artist.add_album(album) it sets album.artist to this_artist.

[Source]

     # File lib/sequel/model/associations.rb, line 478
478:         def reciprocal
479:           cached_fetch(:reciprocal) do
480:             possible_recips = []
481: 
482:             associated_class.all_association_reflections.each do |assoc_reflect|
483:               if reciprocal_association?(assoc_reflect)
484:                 possible_recips << assoc_reflect
485:               end
486:             end
487: 
488:             if possible_recips.length == 1
489:               cached_set(:reciprocal_type, possible_recips.first[:type]) if ambiguous_reciprocal_type?
490:               possible_recips.first[:name]
491:             end
492:           end
493:         end

Whether the reciprocal of this association returns an array of objects instead of a single object, true by default.

[Source]

     # File lib/sequel/model/associations.rb, line 497
497:         def reciprocal_array?
498:           true
499:         end

Name symbol for the remove_all_ association method

[Source]

     # File lib/sequel/model/associations.rb, line 502
502:         def remove_all_method
503:           self[:remove_all_method]
504:         end

Whether associated objects need to be removed from the association before being destroyed in order to preserve referential integrity.

[Source]

     # File lib/sequel/model/associations.rb, line 508
508:         def remove_before_destroy?
509:           true
510:         end

Name symbol for the remove_ association method

[Source]

     # File lib/sequel/model/associations.rb, line 513
513:         def remove_method
514:           self[:remove_method]
515:         end

Whether to check that an object to be disassociated is already associated to this object, false by default.

[Source]

     # File lib/sequel/model/associations.rb, line 518
518:         def remove_should_check_existing?
519:           false
520:         end

Whether this association returns an array of objects instead of a single object, true by default.

[Source]

     # File lib/sequel/model/associations.rb, line 524
524:         def returns_array?
525:           true
526:         end

The columns to select when loading the association.

[Source]

     # File lib/sequel/model/associations.rb, line 529
529:         def select
530:           self[:select]
531:         end

Whether to set the reciprocal association to self when loading associated records, false by default.

[Source]

     # File lib/sequel/model/associations.rb, line 535
535:         def set_reciprocal_to_self?
536:           false
537:         end

Name symbol for the setter association method

[Source]

     # File lib/sequel/model/associations.rb, line 540
540:         def setter_method
541:           self[:setter_method]
542:         end

The range used for slicing when using the :ruby eager limit strategy.

[Source]

     # File lib/sequel/model/associations.rb, line 545
545:         def slice_range(limit_and_offset = limit_and_offset())
546:           limit, offset = limit_and_offset
547:           if limit || offset
548:             (offset||0)..(limit ? (offset||0)+limit-1 : -1)
549:           end
550:         end

[Validate]