class Sequel::Model::Associations::AssociationReflection

  1. lib/sequel/model/associations.rb
Superclass: 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.

Included modules

  1. Sequel::Inflections

Constants

ASSOCIATION_DATASET_PROC = proc{|r| r.association_dataset_for(self)}  
FINALIZE_SETTINGS = { :associated_class=>:class, :associated_dataset=>:_dataset, :eager_limit_strategy=>:_eager_limit_strategy, :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

_add_method()

Name symbol for the _add internal association method

[show source] 
   # File lib/sequel/model/associations.rb
36 def _add_method
37   self[:_add_method]
38 end
_remove_all_method()

Name symbol for the _remove_all internal association method

[show source] 
   # File lib/sequel/model/associations.rb
41 def _remove_all_method
42   self[:_remove_all_method]
43 end
_remove_method()

Name symbol for the _remove internal association method

[show source] 
   # File lib/sequel/model/associations.rb
46 def _remove_method
47   self[:_remove_method]
48 end
_setter_method()

Name symbol for the _setter association method

[show source] 
   # File lib/sequel/model/associations.rb
51 def _setter_method
52   self[:_setter_method]
53 end
add_method()

Name symbol for the add association method

[show source] 
   # File lib/sequel/model/associations.rb
56 def add_method
57   self[:add_method]
58 end
apply_dataset_changes(ds)

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

[show source] 
   # File lib/sequel/model/associations.rb
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
apply_distinct_on_eager_limit_strategy(ds)

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

[show source] 
    # File lib/sequel/model/associations.rb
138 def apply_distinct_on_eager_limit_strategy(ds)
139   keys = predicate_key
140   ds.distinct(*keys).order_prepend(*keys)
141 end
apply_eager_dataset_changes(ds)

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

[show source] 
    # File lib/sequel/model/associations.rb
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_eager_graph_limit_strategy(strategy, ds)

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.

[show source] 
    # File lib/sequel/model/associations.rb
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_eager_limit_strategy(ds, strategy=eager_limit_strategy, limit_and_offset=limit_and_offset())

Apply an eager limit strategy to the dataset, or return the dataset unmodified if it doesn’t need an eager limit strategy.

[show source] 
    # File lib/sequel/model/associations.rb
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
apply_ruby_eager_limit_strategy(rows, limit_and_offset = limit_and_offset())

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.

[show source] 
    # File lib/sequel/model/associations.rb
165 def apply_ruby_eager_limit_strategy(rows, limit_and_offset = limit_and_offset())
166   name = self[:name]
167   return unless range = slice_range(limit_and_offset)
168   if returns_array?
169     rows.each{|o| o.associations[name] = o.associations[name][range] || []}
170   else
171     offset = range.begin
172     rows.each{|o| o.associations[name] = o.associations[name][offset]}
173   end
174 end
apply_window_function_eager_limit_strategy(ds, limit_and_offset=limit_and_offset())

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

[show source] 
    # File lib/sequel/model/associations.rb
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 = ds.order(rn) if ds.db.database_type == :mysql
149   ds = if !returns_array?
150     ds.where(rn => offset ? offset+1 : 1)
151   elsif offset
152     offset += 1
153     if limit
154       ds.where(rn => (offset...(offset+limit))) 
155     else
156       ds.where{SQL::Identifier.new(rn) >= offset} 
157     end
158   else
159     ds.where{SQL::Identifier.new(rn) <= limit} 
160   end
161 end
assign_singular?()

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

[show source] 
    # File lib/sequel/model/associations.rb
178 def assign_singular?
179   !returns_array?
180 end
associated_class()

The class associated to the current model class via this association

[show source] 
   # File lib/sequel/model/associations.rb
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
associated_dataset()

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.

[show source] 
   # File lib/sequel/model/associations.rb
79 def associated_dataset
80   cached_fetch(:_dataset){apply_dataset_changes(_associated_dataset)}
81 end
association_dataset_for(object)

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

[show source] 
    # File lib/sequel/model/associations.rb
215 def association_dataset_for(object)
216   condition = if can_have_associated_objects?(object)
217     predicate_keys.zip(predicate_key_values(object))
218   else
219     false
220   end
221 
222   associated_dataset.where(condition)
223 end
association_dataset_proc()

Proc used to create the association dataset method.

[show source] 
    # File lib/sequel/model/associations.rb
227 def association_dataset_proc
228   ASSOCIATION_DATASET_PROC
229 end
association_method()

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

[show source] 
   # File lib/sequel/model/associations.rb
61 def association_method
62   self[:name]
63 end
can_have_associated_objects?(obj)

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.

[show source] 
    # File lib/sequel/model/associations.rb
185 def can_have_associated_objects?(obj)
186   true
187 end
cloneable?(ref)

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

[show source] 
    # File lib/sequel/model/associations.rb
191 def cloneable?(ref)
192   ref[:type] == self[:type]
193 end
dataset_method()

Name symbol for the dataset association method

[show source] 
    # File lib/sequel/model/associations.rb
196 def dataset_method
197   self[:dataset_method]
198 end
dataset_need_primary_key?()

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

[show source] 
    # File lib/sequel/model/associations.rb
201 def dataset_need_primary_key?
202   true
203 end
delete_row_number_column(ds=associated_dataset)

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

[show source] 
    # File lib/sequel/model/associations.rb
207 def delete_row_number_column(ds=associated_dataset)
208   if eager_limit_strategy == :window_function
209     ds.row_number_column 
210   end
211 end
eager_graph_lazy_dataset?()

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.

[show source] 
    # File lib/sequel/model/associations.rb
339 def eager_graph_lazy_dataset?
340   true
341 end
eager_graph_limit_strategy(strategy)

The eager_graph limit strategy to use for this dataset

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

The eager limit strategy to use for this dataset.

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

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

[show source] 
    # File lib/sequel/model/associations.rb
264 def eager_load_results(eo, &block)
265   rows = eo[:rows]
266   unless eo[:initialize_rows] == false
267     Sequel.synchronize_with(eo[:mutex]){initialize_association_cache(rows)}
268   end
269   if eo[:id_map]
270     ids = eo[:id_map].keys
271     return ids if ids.empty?
272   end
273   strategy = eager_limit_strategy
274   cascade = eo[:associations]
275   eager_limit = nil
276 
277   if eo[:no_results]
278     no_results = true
279   elsif eo[:eager_block] || eo[:loader] == false
280     ds = eager_loading_dataset(eo)
281 
282     strategy = ds.opts[:eager_limit_strategy] || strategy
283 
284     eager_limit =
285       if el = ds.opts[:eager_limit]
286         raise Error, "The :eager_limit dataset option is not supported for associations returning a single record" unless returns_array?
287         strategy ||= true_eager_graph_limit_strategy
288         if el.is_a?(Array)
289           el
290         else
291           [el, nil]
292         end
293       else
294         limit_and_offset
295       end
296 
297     strategy = true_eager_graph_limit_strategy if strategy == :union
298     # Correlated subqueries are not supported for regular eager loading
299     strategy = :ruby if strategy == :correlated_subquery
300     strategy = nil if strategy == :ruby && assign_singular?
301     objects = apply_eager_limit_strategy(ds, strategy, eager_limit).all
302   elsif strategy == :union
303     objects = []
304     ds = associated_dataset
305     loader = union_eager_loader
306     joiner = " UNION ALL "
307     ids.each_slice(subqueries_per_union).each do |slice|
308       objects.concat(ds.with_sql(slice.map{|k| loader.sql(*k)}.join(joiner)).to_a)
309     end
310     ds = ds.eager(cascade) if cascade
311     ds.send(:post_load, objects)
312   else
313     loader = placeholder_eager_loader
314     loader = loader.with_dataset{|dataset| dataset.eager(cascade)} if cascade
315     objects = loader.all(ids)
316   end
317 
318   Sequel.synchronize_with(eo[:mutex]){objects.each(&block)} unless no_results
319 
320   if strategy == :ruby
321     apply_ruby_eager_limit_strategy(rows, eager_limit || limit_and_offset)
322   end
323 end
eager_loader_key()

The key to use for the key hash when eager loading

[show source] 
    # File lib/sequel/model/associations.rb
326 def eager_loader_key
327   self[:eager_loader_key]
328 end
eager_loading_use_associated_key?()

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

[show source] 
    # File lib/sequel/model/associations.rb
332 def eager_loading_use_associated_key?
333   false
334 end
filter_by_associations_add_conditions?()

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

[show source] 
    # File lib/sequel/model/associations.rb
345 def filter_by_associations_add_conditions?
346   self[:conditions] || self[:eager_block] || self[:limit]
347 end
filter_by_associations_conditions_expression(obj)

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.

[show source] 
    # File lib/sequel/model/associations.rb
353 def filter_by_associations_conditions_expression(obj)
354   ds = filter_by_associations_conditions_dataset.where(filter_by_associations_conditions_subquery_conditions(obj))
355   {filter_by_associations_conditions_key=>ds}
356 end
finalize()

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.

[show source] 
    # File lib/sequel/model/associations.rb
361 def finalize
362   return unless cache = self[:cache]
363 
364   finalizer = proc do |meth, key|
365     next if has_key?(key)
366 
367     # Allow calling private methods to make sure caching is done appropriately
368     send(meth)
369     self[key] = cache.delete(key) if cache.has_key?(key)
370   end
371 
372   finalize_settings.each(&finalizer)
373 
374   unless self[:instance_specific]
375     finalizer.call(:associated_eager_dataset, :associated_eager_dataset)
376     finalizer.call(:filter_by_associations_conditions_dataset, :filter_by_associations_conditions_dataset)
377   end
378 
379   nil
380 end
finalize_settings()
[show source] 
    # File lib/sequel/model/associations.rb
392 def finalize_settings
393   FINALIZE_SETTINGS
394 end
handle_silent_modification_failure?()

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

[show source] 
    # File lib/sequel/model/associations.rb
398 def handle_silent_modification_failure?
399   false
400 end
initialize_association_cache(objects)

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

[show source] 
    # File lib/sequel/model/associations.rb
403 def initialize_association_cache(objects)
404   name = self[:name]
405   if assign_singular?
406     objects.each{|object| object.associations[name] = nil}
407   else
408     objects.each{|object| object.associations[name] = []}
409   end
410 end
inspect()

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

[show source] 
    # File lib/sequel/model/associations.rb
414 def inspect
415   o = self[:orig_opts].dup
416   o.delete(:class)
417   o.delete(:class_name)
418   o.delete(:block) unless o[:block]
419   o[:class] = self[:orig_class] if self[:orig_class]
420 
421   "#<#{self.class} #{self[:model]}.#{self[:type]} #{self[:name].inspect}#{", #{o.inspect[1...-1]}" unless o.empty?}>"
422 end
limit_and_offset()

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

[show source] 
    # File lib/sequel/model/associations.rb
425 def limit_and_offset
426   if (v = self[:limit]).is_a?(Array)
427     v
428   else
429     [v, nil]
430   end
431 end
need_associated_primary_key?()

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

[show source] 
    # File lib/sequel/model/associations.rb
435 def need_associated_primary_key?
436   false
437 end
placeholder_loader()

A placeholder literalizer that can be used to lazily load the association. If one can’t be used, returns nil.

[show source] 
    # File lib/sequel/model/associations.rb
441 def placeholder_loader
442   if use_placeholder_loader?
443     cached_fetch(:placeholder_loader) do
444       Sequel::Dataset::PlaceholderLiteralizer.loader(associated_dataset) do |pl, ds|
445         ds = ds.where(Sequel.&(*predicate_keys.map{|k| SQL::BooleanExpression.new(:'=', k, pl.arg)}))
446         if self[:block]
447           ds = self[:block].call(ds)
448         end
449         ds
450       end
451     end
452   end
453 end
predicate_key_values(object)

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

[show source] 
    # File lib/sequel/model/associations.rb
461 def predicate_key_values(object)
462   predicate_key_methods.map{|k| object.get_column_value(k)}
463 end
predicate_keys()

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

[show source] 
    # File lib/sequel/model/associations.rb
456 def predicate_keys
457   cached_fetch(:predicate_keys){Array(predicate_key)}
458 end
qualify(table, col)

Qualify col with the given table name.

[show source] 
    # File lib/sequel/model/associations.rb
466 def qualify(table, col)
467   transform(col) do |k|
468     case k
469     when Symbol, SQL::Identifier
470       SQL::QualifiedIdentifier.new(table, k)
471     else
472       Sequel::Qualifier.new(table).transform(k)
473     end
474   end
475 end
qualify_assoc(col)

Qualify col with the associated model’s table name.

[show source] 
    # File lib/sequel/model/associations.rb
478 def qualify_assoc(col)
479   qualify(associated_class.table_name, col)
480 end
qualify_cur(col)

Qualify col with the current model’s table name.

[show source] 
    # File lib/sequel/model/associations.rb
483 def qualify_cur(col)
484   qualify(self[:model].table_name, col)
485 end
reciprocal()

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.

[show source] 
    # File lib/sequel/model/associations.rb
493 def reciprocal
494   cached_fetch(:reciprocal) do
495     possible_recips = []
496 
497     associated_class.all_association_reflections.each do |assoc_reflect|
498       if reciprocal_association?(assoc_reflect)
499         possible_recips << assoc_reflect
500       end
501     end
502 
503     if possible_recips.length == 1
504       cached_set(:reciprocal_type, possible_recips.first[:type]) if ambiguous_reciprocal_type?
505       possible_recips.first[:name]
506     end
507   end
508 end
reciprocal_array?()

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

[show source] 
    # File lib/sequel/model/associations.rb
512 def reciprocal_array?
513   true
514 end
remove_all_method()

Name symbol for the remove_all_ association method

[show source] 
    # File lib/sequel/model/associations.rb
517 def remove_all_method
518   self[:remove_all_method]
519 end
remove_before_destroy?()

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

[show source] 
    # File lib/sequel/model/associations.rb
523 def remove_before_destroy?
524   true
525 end
remove_method()

Name symbol for the remove_ association method

[show source] 
    # File lib/sequel/model/associations.rb
528 def remove_method
529   self[:remove_method]
530 end
remove_should_check_existing?()

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

[show source] 
    # File lib/sequel/model/associations.rb
533 def remove_should_check_existing?
534   false
535 end
returns_array?()

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

[show source] 
    # File lib/sequel/model/associations.rb
539 def returns_array?
540   true
541 end
select()

The columns to select when loading the association.

[show source] 
    # File lib/sequel/model/associations.rb
544 def select
545   self[:select]
546 end
set_reciprocal_to_self?()

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

[show source] 
    # File lib/sequel/model/associations.rb
550 def set_reciprocal_to_self?
551   false
552 end
setter_method()

Name symbol for the setter association method

[show source] 
    # File lib/sequel/model/associations.rb
555 def setter_method
556   self[:setter_method]
557 end
slice_range(limit_and_offset = limit_and_offset())

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

[show source] 
    # File lib/sequel/model/associations.rb
560 def slice_range(limit_and_offset = limit_and_offset())
561   limit, offset = limit_and_offset
562   if limit || offset
563     (offset||0)..(limit ? (offset||0)+limit-1 : -1)
564   end
565 end