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   if returns_array?
168     range = slice_range(limit_and_offset)
169     rows.each{|o| o.associations[name] = o.associations[name][range] || []}
170   elsif sr = slice_range(limit_and_offset)
171     offset = sr.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
334 def eager_graph_lazy_dataset?
335   true
336 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   initialize_association_cache(rows) unless eo[:initialize_rows] == false
267   if eo[:id_map]
268     ids = eo[:id_map].keys
269     return ids if ids.empty?
270   end
271   strategy = eager_limit_strategy
272   cascade = eo[:associations]
273   eager_limit = nil
274 
275   if eo[:eager_block] || eo[:loader] == false
276     ds = eager_loading_dataset(eo)
277 
278     strategy = ds.opts[:eager_limit_strategy] || strategy
279 
280     eager_limit =
281       if el = ds.opts[:eager_limit]
282         raise Error, "The :eager_limit dataset option is not supported for associations returning a single record" unless returns_array?
283         strategy ||= true_eager_graph_limit_strategy
284         if el.is_a?(Array)
285           el
286         else
287           [el, nil]
288         end
289       else
290         limit_and_offset
291       end
292 
293     strategy = true_eager_graph_limit_strategy if strategy == :union
294     # Correlated subqueries are not supported for regular eager loading
295     strategy = :ruby if strategy == :correlated_subquery
296     strategy = nil if strategy == :ruby && assign_singular?
297     objects = apply_eager_limit_strategy(ds, strategy, eager_limit).all
298   elsif strategy == :union
299     objects = []
300     ds = associated_dataset
301     loader = union_eager_loader
302     joiner = " UNION ALL "
303     ids.each_slice(subqueries_per_union).each do |slice|
304       objects.concat(ds.with_sql(slice.map{|k| loader.sql(*k)}.join(joiner)).to_a)
305     end
306     ds = ds.eager(cascade) if cascade
307     ds.send(:post_load, objects)
308   else
309     loader = placeholder_eager_loader
310     loader = loader.with_dataset{|dataset| dataset.eager(cascade)} if cascade
311     objects = loader.all(ids)
312   end
313 
314   objects.each(&block)
315   if strategy == :ruby
316     apply_ruby_eager_limit_strategy(rows, eager_limit || limit_and_offset)
317   end
318 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
321 def eager_loader_key
322   self[:eager_loader_key]
323 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
327 def eager_loading_use_associated_key?
328   false
329 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
340 def filter_by_associations_add_conditions?
341   self[:conditions] || self[:eager_block] || self[:limit]
342 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
348 def filter_by_associations_conditions_expression(obj)
349   ds = filter_by_associations_conditions_dataset.where(filter_by_associations_conditions_subquery_conditions(obj))
350   {filter_by_associations_conditions_key=>ds}
351 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
356 def finalize
357   return unless cache = self[:cache]
358 
359   finalize_settings.each do |meth, key|
360     next if has_key?(key)
361 
362     # Allow calling private methods to make sure caching is done appropriately
363     send(meth)
364     self[key] = cache.delete(key) if cache.has_key?(key)
365   end
366 
367   nil
368 end
finalize_settings() click to toggle source
    # File lib/sequel/model/associations.rb
382 def finalize_settings
383   FINALIZE_SETTINGS
384 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
388 def handle_silent_modification_failure?
389   false
390 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
393 def initialize_association_cache(objects)
394   name = self[:name]
395   if assign_singular?
396     objects.each{|object| object.associations[name] = nil}
397   else
398     objects.each{|object| object.associations[name] = []}
399   end
400 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
404 def inspect
405   o = self[:orig_opts].dup
406   o.delete(:class)
407   o.delete(:class_name)
408   o.delete(:block) unless o[:block]
409   o[:class] = self[:orig_class] if self[:orig_class]
410 
411   "#<#{self.class} #{self[:model]}.#{self[:type]} #{self[:name].inspect}#{", #{o.inspect[1...-1]}" unless o.empty?}>"
412 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
415 def limit_and_offset
416   if (v = self[:limit]).is_a?(Array)
417     v
418   else
419     [v, nil]
420   end
421 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
425 def need_associated_primary_key?
426   false
427 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
431 def placeholder_loader
432   if use_placeholder_loader?
433     cached_fetch(:placeholder_loader) do
434       Sequel::Dataset::PlaceholderLiteralizer.loader(associated_dataset) do |pl, ds|
435         ds.where(Sequel.&(*predicate_keys.map{|k| SQL::BooleanExpression.new(:'=', k, pl.arg)}))
436       end
437     end
438   end
439 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
447 def predicate_key_values(object)
448   predicate_key_methods.map{|k| object.get_column_value(k)}
449 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
442 def predicate_keys
443   cached_fetch(:predicate_keys){Array(predicate_key)}
444 end
qualify(table, col) click to toggle source

Qualify col with the given table name.

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

Qualify col with the associated model's table name.

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

Qualify col with the current model's table name.

    # File lib/sequel/model/associations.rb
469 def qualify_cur(col)
470   qualify(self[:model].table_name, col)
471 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
479 def reciprocal
480   cached_fetch(:reciprocal) do
481     possible_recips = []
482 
483     associated_class.all_association_reflections.each do |assoc_reflect|
484       if reciprocal_association?(assoc_reflect)
485         possible_recips << assoc_reflect
486       end
487     end
488 
489     if possible_recips.length == 1
490       cached_set(:reciprocal_type, possible_recips.first[:type]) if ambiguous_reciprocal_type?
491       possible_recips.first[:name]
492     end
493   end
494 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
498 def reciprocal_array?
499   true
500 end
remove_all_method() click to toggle source

Name symbol for the remove_all_ association method

    # File lib/sequel/model/associations.rb
503 def remove_all_method
504   self[:remove_all_method]
505 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
509 def remove_before_destroy?
510   true
511 end
remove_method() click to toggle source

Name symbol for the remove_ association method

    # File lib/sequel/model/associations.rb
514 def remove_method
515   self[:remove_method]
516 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
519 def remove_should_check_existing?
520   false
521 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
525 def returns_array?
526   true
527 end
select() click to toggle source

The columns to select when loading the association.

    # File lib/sequel/model/associations.rb
530 def select
531   self[:select]
532 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
536 def set_reciprocal_to_self?
537   false
538 end
setter_method() click to toggle source

Name symbol for the setter association method

    # File lib/sequel/model/associations.rb
541 def setter_method
542   self[:setter_method]
543 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
546 def slice_range(limit_and_offset = limit_and_offset())
547   limit, offset = limit_and_offset
548   if limit || offset
549     (offset||0)..(limit ? (offset||0)+limit-1 : -1)
550   end
551 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
576 def _associated_dataset
577   associated_class.dataset
578 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
582 def ambiguous_reciprocal_type?
583   false
584 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
602 def apply_filter_by_associations_distinct_on_limit_strategy(ds)
603   k = filter_by_associations_limit_key 
604   ds.where(k=>apply_distinct_on_eager_limit_strategy(associated_eager_dataset.select(*k)))
605 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
588 def apply_filter_by_associations_limit_strategy(ds)
589   case filter_by_associations_limit_strategy
590   when :distinct_on
591     apply_filter_by_associations_distinct_on_limit_strategy(ds)
592   when :window_function
593     apply_filter_by_associations_window_function_limit_strategy(ds)
594   else
595     ds
596   end
597 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
610 def apply_filter_by_associations_window_function_limit_strategy(ds)
611   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))
612 end
associated_eager_dataset() click to toggle source

The associated_dataset with the eager_block callback already applied.

    # File lib/sequel/model/associations.rb
615 def associated_eager_dataset
616   cached_fetch(:associated_eager_dataset) do
617     ds = associated_dataset.unlimited
618     if block = self[:eager_block]
619       ds = block.call(ds)
620     end
621     ds
622   end
623 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
559 def cached_fetch(key)
560   fetch(key) do
561     return yield unless h = self[:cache]
562     Sequel.synchronize{return h[key] if h.has_key?(key)}
563     value = yield
564     Sequel.synchronize{h[key] = value}
565   end
566 end
cached_set(key, value) click to toggle source

Cache the value at the given key if caching.

    # File lib/sequel/model/associations.rb
569 def cached_set(key, value)
570   return unless h = self[:cache]
571   Sequel.synchronize{h[key] = value}
572 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
654 def default_eager_limit_strategy
655   self[:model].default_eager_limit_strategy || :ruby
656 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
627 def eager_loading_dataset(eo=OPTS)
628   ds = eo[:dataset] || associated_eager_dataset
629   if id_map = eo[:id_map]
630     ds = ds.where(eager_loading_predicate_condition(id_map.keys))
631   end
632   if associations = eo[:associations]
633     ds = ds.eager(associations)
634   end
635   if block = eo[:eager_block]
636     orig_ds = ds
637     ds = block.call(ds)
638   end
639   if eager_loading_use_associated_key?
640     ds = if ds.opts[:eager_graph] && !orig_ds.opts[:eager_graph]
641       block.call(orig_ds.select_append(*associated_key_array))
642     else
643       ds.select_append(*associated_key_array)
644     end
645   end
646   if self[:eager_graph]
647     raise(Error, "cannot eagerly load a #{self[:type]} association that uses :eager_graph") if eager_loading_use_associated_key?
648     ds = ds.eager_graph(self[:eager_graph])
649   end
650   ds
651 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
659 def eager_loading_predicate_condition(keys)
660   {predicate_key=>keys}
661 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
665 def filter_by_associations_add_conditions_dataset_filter(ds)
666   k = filter_by_associations_conditions_associated_keys
667   ds.select(*k).where(Sequel.negate(k.zip([])))
668 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
688 def filter_by_associations_conditions_dataset
689   cached_fetch(:filter_by_associations_conditions_dataset) do
690     ds = associated_eager_dataset.unordered
691     ds = filter_by_associations_add_conditions_dataset_filter(ds)
692     ds = apply_filter_by_associations_limit_strategy(ds)
693     ds
694   end
695 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
673 def filter_by_associations_conditions_subquery_conditions(obj)
674   key = qualify(associated_class.table_name, associated_class.primary_key)
675   case obj
676   when Array
677     {key=>obj.map(&:pk)}
678   when Sequel::Dataset
679     {key=>obj.select(*Array(qualify(associated_class.table_name, associated_class.primary_key)))}
680   else
681     Array(key).zip(Array(obj.pk))
682   end
683 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
698 def filter_by_associations_limit_strategy
699   v = fetch(:filter_limit_strategy, self[:eager_limit_strategy])
700   if v || self[:limit] || !returns_array?
701     case v ||= self[:model].default_eager_limit_strategy
702     when true, :union, :ruby
703       # Can't use a union or ruby-based strategy for filtering by associations, switch to default eager graph limit
704       # strategy.
705       true_eager_graph_limit_strategy
706     when Symbol
707       v
708     end
709   end
710 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
713 def limit_to_single_row?
714   !returns_array?
715 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
718 def offset
719   limit_and_offset.last
720 end
placeholder_eager_loader() click to toggle source

A placeholder literalizer used to speed up eager loading.

    # File lib/sequel/model/associations.rb
723 def placeholder_eager_loader
724   cached_fetch(:placeholder_eager_loader) do
725     Sequel::Dataset::PlaceholderLiteralizer.loader(associated_dataset) do |pl, ds|
726       apply_eager_limit_strategy(eager_loading_dataset.where(predicate_key=>pl.arg), eager_limit_strategy)
727     end
728   end
729 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
733 def possible_reciprocal_types
734   [reciprocal_type]
735 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
739 def reciprocal_association?(assoc_reflect)
740   possible_reciprocal_types.include?(assoc_reflect[:type]) &&
741     (begin; assoc_reflect.associated_class; rescue NameError; end) == self[:model] &&
742     assoc_reflect[:conditions].nil? &&
743     assoc_reflect[:block].nil?
744 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
749 def subqueries_per_union
750   self[:subqueries_per_union] || 40
751 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
755 def transform(s, &block)
756   s.is_a?(Array) ? s.map(&block) : (yield s)
757 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
773 def true_eager_graph_limit_strategy
774   if associated_class.dataset.supports_window_functions?
775     :window_function
776   else
777     :ruby
778   end
779 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
761 def true_eager_limit_strategy
762   if self[:eager_graph] || (offset && !associated_dataset.supports_offsets_in_correlated_subqueries?)
763     # An SQL-based approach won't work if you are also eager graphing,
764     # so use a ruby based approach in that case.
765     :ruby
766   else
767     :union 
768   end
769 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
783 def union_eager_loader
784   cached_fetch(:union_eager_loader) do
785     Sequel::Dataset::PlaceholderLiteralizer.loader(associated_dataset) do |pl, ds|
786       ds = self[:eager_block].call(ds) if self[:eager_block]
787       keys = predicate_keys
788       ds = ds.where(keys.map{pl.arg}.zip(keys))
789       if eager_loading_use_associated_key?
790         ds = ds.select_append(*associated_key_array)
791       end
792       ds.from_self
793     end
794   end
795 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
798 def use_placeholder_loader?
799   !self[:instance_specific] && !self[:eager_graph]
800 end