class Sequel::Model::Associations::AssociationReflection

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.

Constants

ASSOCIATION_DATASET_PROC
FINALIZE_SETTINGS

Map of methods to cache keys used for finalizing associations.

Public Instance Methods

_add_method() click to toggle source

Name symbol for the _add internal association method

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

Name symbol for the _remove_all internal association method

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

Name symbol for the _remove internal association method

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

Name symbol for the _setter association method

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

Name symbol for the add association method

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

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

   # 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) click to toggle source

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

    # 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) click to toggle source

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

    # 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) click to toggle source

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.

    # 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()) click to toggle source

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

    # 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()) click to toggle source

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.

    # 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()) click to toggle source

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

    # 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?() click to toggle source

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

    # File lib/sequel/model/associations.rb
178 def assign_singular?
179   !returns_array?
180 end
associated_class() click to toggle source

The class associated to the current model class via this association

   # 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() click to toggle source

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.

   # 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) click to toggle source

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

    # 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() click to toggle source

Proc used to create the association dataset method.

    # File lib/sequel/model/associations.rb
227 def association_dataset_proc
228   ASSOCIATION_DATASET_PROC
229 end
association_method() click to toggle source

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

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

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.

    # File lib/sequel/model/associations.rb
185 def can_have_associated_objects?(obj)
186   true
187 end
cloneable?(ref) click to toggle source

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

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

Name symbol for the dataset association method

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

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

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

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

    # 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?() click to toggle source

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.

    # File lib/sequel/model/associations.rb
339 def eager_graph_lazy_dataset?
340   true
341 end
eager_graph_limit_strategy(strategy) click to toggle source

The eager_graph limit strategy to use for this dataset

    # 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() click to toggle source

The eager limit strategy to use for this dataset.

    # 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) click to toggle source

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

    # 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() click to toggle source

The key to use for the key hash when eager loading

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

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

    # File lib/sequel/model/associations.rb
332 def eager_loading_use_associated_key?
333   false
334 end
filter_by_associations_add_conditions?() click to toggle source

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

    # 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) click to toggle source

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.

    # 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() click to toggle source

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.

    # 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() click to toggle source
    # File lib/sequel/model/associations.rb
392 def finalize_settings
393   FINALIZE_SETTINGS
394 end
handle_silent_modification_failure?() click to toggle source

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

    # File lib/sequel/model/associations.rb
398 def handle_silent_modification_failure?
399   false
400 end
initialize_association_cache(objects) click to toggle source

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

    # 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() click to toggle source

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

    # 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() click to toggle source

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

    # 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?() click to toggle source

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

    # File lib/sequel/model/associations.rb
435 def need_associated_primary_key?
436   false
437 end
placeholder_loader() click to toggle source

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

    # 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) click to toggle source

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

    # 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() click to toggle source

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

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

Qualify col with the given table name.

    # 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) click to toggle source

Qualify col with the associated model’s table name.

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

Qualify col with the current model’s table name.

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

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.

    # 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?() click to toggle source

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

    # File lib/sequel/model/associations.rb
512 def reciprocal_array?
513   true
514 end
remove_all_method() click to toggle source

Name symbol for the remove_all_ association method

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

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

    # File lib/sequel/model/associations.rb
523 def remove_before_destroy?
524   true
525 end
remove_method() click to toggle source

Name symbol for the remove_ association method

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

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

    # File lib/sequel/model/associations.rb
533 def remove_should_check_existing?
534   false
535 end
returns_array?() click to toggle source

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

    # File lib/sequel/model/associations.rb
539 def returns_array?
540   true
541 end
select() click to toggle source

The columns to select when loading the association.

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

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

    # File lib/sequel/model/associations.rb
550 def set_reciprocal_to_self?
551   false
552 end
setter_method() click to toggle source

Name symbol for the setter association method

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

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

    # 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

Private Instance Methods

_associated_dataset() click to toggle source

The base dataset used for the association, before any order/conditions options have been applied.

    # File lib/sequel/model/associations.rb
590 def _associated_dataset
591   associated_class.dataset
592 end
ambiguous_reciprocal_type?() click to toggle source

Whether for the reciprocal type for the given association cannot be known in advantage, false by default.

    # File lib/sequel/model/associations.rb
596 def ambiguous_reciprocal_type?
597   false
598 end
apply_filter_by_associations_distinct_on_limit_strategy(ds) click to toggle source

Apply a distinct on eager limit strategy using IN with a subquery that uses DISTINCT ON to ensure only the first matching record for each key is included.

    # File lib/sequel/model/associations.rb
616 def apply_filter_by_associations_distinct_on_limit_strategy(ds)
617   k = filter_by_associations_limit_key 
618   ds.where(k=>apply_distinct_on_eager_limit_strategy(associated_eager_dataset.select(*k)))
619 end
apply_filter_by_associations_limit_strategy(ds) click to toggle source

Apply a limit strategy to the given dataset so that filter by associations works with a limited dataset.

    # File lib/sequel/model/associations.rb
602 def apply_filter_by_associations_limit_strategy(ds)
603   case filter_by_associations_limit_strategy
604   when :distinct_on
605     apply_filter_by_associations_distinct_on_limit_strategy(ds)
606   when :window_function
607     apply_filter_by_associations_window_function_limit_strategy(ds)
608   else
609     ds
610   end
611 end
apply_filter_by_associations_window_function_limit_strategy(ds) click to toggle source

Apply a distinct on eager limit strategy using IN with a subquery that uses a filter on the row_number window function to ensure that only rows inside the limit are returned.

    # File lib/sequel/model/associations.rb
624 def apply_filter_by_associations_window_function_limit_strategy(ds)
625   ds.where(filter_by_associations_limit_key=>apply_window_function_eager_limit_strategy(associated_eager_dataset.select(*filter_by_associations_limit_alias_key)).select(*filter_by_associations_limit_aliases))
626 end
associated_eager_dataset() click to toggle source

The associated_dataset with the eager_block callback already applied.

    # File lib/sequel/model/associations.rb
629 def associated_eager_dataset
630   cached_fetch(:associated_eager_dataset) do
631     ds = associated_dataset.unlimited
632     if block = self[:eager_block]
633       ds = block.call(ds)
634     end
635     ds
636   end
637 end
cached_fetch(key) { || ... } click to toggle source

If the key exists in the reflection hash, return it. If the key doesn’t exist and association reflections are uncached, then yield to get the value. If the key doesn’t exist and association reflection are cached, check the cache and return the value if present, or yield to get the value, cache the value, and return it.

    # File lib/sequel/model/associations.rb
573 def cached_fetch(key)
574   fetch(key) do
575     return yield unless h = self[:cache]
576     Sequel.synchronize{return h[key] if h.has_key?(key)}
577     value = yield
578     Sequel.synchronize{h[key] = value}
579   end
580 end
cached_set(key, value) click to toggle source

Cache the value at the given key if caching.

    # File lib/sequel/model/associations.rb
583 def cached_set(key, value)
584   return unless h = self[:cache]
585   Sequel.synchronize{h[key] = value}
586 end
default_eager_limit_strategy() click to toggle source

The default eager limit strategy to use for this association

    # File lib/sequel/model/associations.rb
666 def default_eager_limit_strategy
667   self[:model].default_eager_limit_strategy || :ruby
668 end
eager_loading_dataset(eo=OPTS) click to toggle source

The dataset to use for eager loading associated objects for multiple current objects, given the hash passed to the eager loader.

    # File lib/sequel/model/associations.rb
641 def eager_loading_dataset(eo=OPTS)
642   ds = eo[:dataset] || associated_eager_dataset
643   ds = eager_loading_set_predicate_condition(ds, eo)
644   if associations = eo[:associations]
645     ds = ds.eager(associations)
646   end
647   if block = eo[:eager_block]
648     orig_ds = ds
649     ds = block.call(ds)
650   end
651   if eager_loading_use_associated_key?
652     ds = if ds.opts[:eager_graph] && !orig_ds.opts[:eager_graph]
653       block.call(orig_ds.select_append(*associated_key_array))
654     else
655       ds.select_append(*associated_key_array)
656     end
657   end
658   if self[:eager_graph]
659     raise(Error, "cannot eagerly load a #{self[:type]} association that uses :eager_graph") if eager_loading_use_associated_key?
660     ds = ds.eager_graph(self[:eager_graph])
661   end
662   ds
663 end
eager_loading_predicate_condition(keys) click to toggle source

The predicate condition to use for the eager_loader.

    # File lib/sequel/model/associations.rb
680 def eager_loading_predicate_condition(keys)
681   {predicate_key=>keys}
682 end
eager_loading_set_predicate_condition(ds, eo) click to toggle source

Set the predicate condition for the eager loading dataset based on the id map in the eager loading options.

    # File lib/sequel/model/associations.rb
672 def eager_loading_set_predicate_condition(ds, eo)
673   if id_map = eo[:id_map]
674     ds = ds.where(eager_loading_predicate_condition(id_map.keys))
675   end
676   ds
677 end
filter_by_associations_add_conditions_dataset_filter(ds) click to toggle source

Add conditions to the dataset to not include NULL values for the associated keys, and select those keys.

    # File lib/sequel/model/associations.rb
686 def filter_by_associations_add_conditions_dataset_filter(ds)
687   k = filter_by_associations_conditions_associated_keys
688   ds.select(*k).where(Sequel.negate(k.zip([])))
689 end
filter_by_associations_conditions_dataset() click to toggle source

The base dataset to use for the filter by associations conditions subquery, regardless of the objects that are passed in as filter values.

    # File lib/sequel/model/associations.rb
709 def filter_by_associations_conditions_dataset
710   cached_fetch(:filter_by_associations_conditions_dataset) do
711     ds = associated_eager_dataset.unordered
712     ds = filter_by_associations_add_conditions_dataset_filter(ds)
713     ds = apply_filter_by_associations_limit_strategy(ds)
714     ds
715   end
716 end
filter_by_associations_conditions_subquery_conditions(obj) click to toggle source

The conditions to add to the filter by associations conditions subquery to restrict it to to the object(s) that was used as the filter value.

    # File lib/sequel/model/associations.rb
694 def filter_by_associations_conditions_subquery_conditions(obj)
695   key = qualify(associated_class.table_name, associated_class.primary_key)
696   case obj
697   when Array
698     {key=>obj.map(&:pk)}
699   when Sequel::Dataset
700     {key=>obj.select(*Array(qualify(associated_class.table_name, associated_class.primary_key)))}
701   else
702     Array(key).zip(Array(obj.pk))
703   end
704 end
filter_by_associations_limit_strategy() click to toggle source

The strategy to use to filter by a limited association

    # File lib/sequel/model/associations.rb
719 def filter_by_associations_limit_strategy
720   v = fetch(:filter_limit_strategy, self[:eager_limit_strategy])
721   if v || self[:limit] || !returns_array?
722     case v ||= self[:model].default_eager_limit_strategy
723     when true, :union, :ruby
724       # Can't use a union or ruby-based strategy for filtering by associations, switch to default eager graph limit
725       # strategy.
726       true_eager_graph_limit_strategy
727     when Symbol
728       v
729     end
730   end
731 end
limit_to_single_row?() click to toggle source

Whether to limit the associated dataset to a single row.

    # File lib/sequel/model/associations.rb
734 def limit_to_single_row?
735   !returns_array?
736 end
offset() click to toggle source

Any offset to use for this association (or nil if there is no offset).

    # File lib/sequel/model/associations.rb
739 def offset
740   limit_and_offset.last
741 end
placeholder_eager_loader() click to toggle source

A placeholder literalizer used to speed up eager loading.

    # File lib/sequel/model/associations.rb
744 def placeholder_eager_loader
745   cached_fetch(:placeholder_eager_loader) do
746     Sequel::Dataset::PlaceholderLiteralizer.loader(associated_dataset) do |pl, ds|
747       apply_eager_limit_strategy(eager_loading_dataset.where(predicate_key=>pl.arg), eager_limit_strategy)
748     end
749   end
750 end
possible_reciprocal_types() click to toggle source

The reciprocal type as an array, should be overridden in reflection subclasses that have ambiguous reciprocal types.

    # File lib/sequel/model/associations.rb
754 def possible_reciprocal_types
755   [reciprocal_type]
756 end
reciprocal_association?(assoc_reflect) click to toggle source

Whether the given association reflection is possible reciprocal association for the current association reflection.

    # File lib/sequel/model/associations.rb
760 def reciprocal_association?(assoc_reflect)
761   possible_reciprocal_types.include?(assoc_reflect[:type]) &&
762     (begin; assoc_reflect.associated_class; rescue NameError; end) == self[:model] &&
763     assoc_reflect[:conditions].nil? &&
764     assoc_reflect[:block].nil?
765 end
subqueries_per_union() click to toggle source

The number of subqueries to use in each union query, used to eagerly load limited associations. Defaults to 40, the optimal number depends on the latency between the database and the application.

    # File lib/sequel/model/associations.rb
770 def subqueries_per_union
771   self[:subqueries_per_union] || 40
772 end
transform(s) { |s)| ... } click to toggle source

If s is an array, map s over the block. Otherwise, just call the block with s.

    # File lib/sequel/model/associations.rb
776 def transform(s, &block)
777   s.is_a?(Array) ? s.map(&block) : (yield s)
778 end
true_eager_graph_limit_strategy() click to toggle source

The eager_graph limit strategy used when true is given as the value, choosing the best strategy based on what the database supports.

    # File lib/sequel/model/associations.rb
794 def true_eager_graph_limit_strategy
795   if associated_class.dataset.supports_window_functions?
796     :window_function
797   else
798     :ruby
799   end
800 end
true_eager_limit_strategy() click to toggle source

What eager limit strategy should be used when true is given as the value, defaults to UNION as that is the fastest strategy if the appropriate keys are indexed.

    # File lib/sequel/model/associations.rb
782 def true_eager_limit_strategy
783   if self[:eager_graph] || (offset && !associated_dataset.supports_offsets_in_correlated_subqueries?)
784     # An SQL-based approach won't work if you are also eager graphing,
785     # so use a ruby based approach in that case.
786     :ruby
787   else
788     :union 
789   end
790 end
union_eager_loader() click to toggle source

A placeholder literalizer used to speed up the creation of union queries when eager loading a limited association.

    # File lib/sequel/model/associations.rb
804 def union_eager_loader
805   cached_fetch(:union_eager_loader) do
806     Sequel::Dataset::PlaceholderLiteralizer.loader(associated_dataset) do |pl, ds|
807       ds = self[:eager_block].call(ds) if self[:eager_block]
808       keys = predicate_keys
809       ds = ds.where(keys.map{pl.arg}.zip(keys))
810       if eager_loading_use_associated_key?
811         ds = ds.select_append(*associated_key_array)
812       end
813       ds.from_self
814     end
815   end
816 end
use_placeholder_loader?() click to toggle source

Whether the placeholder loader can be used to load the association.

    # File lib/sequel/model/associations.rb
819 def use_placeholder_loader?
820   self[:use_placeholder_loader]
821 end