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
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   finalizer = proc 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   finalize_settings.each(&finalizer)
368 
369   unless self[:instance_specific]
370     finalizer.call(:associated_eager_dataset, :associated_eager_dataset)
371     finalizer.call(:filter_by_associations_conditions_dataset, :filter_by_associations_conditions_dataset)
372   end
373 
374   nil
375 end
finalize_settings() click to toggle source
    # File lib/sequel/model/associations.rb
387 def finalize_settings
388   FINALIZE_SETTINGS
389 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
393 def handle_silent_modification_failure?
394   false
395 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
398 def initialize_association_cache(objects)
399   name = self[:name]
400   if assign_singular?
401     objects.each{|object| object.associations[name] = nil}
402   else
403     objects.each{|object| object.associations[name] = []}
404   end
405 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
409 def inspect
410   o = self[:orig_opts].dup
411   o.delete(:class)
412   o.delete(:class_name)
413   o.delete(:block) unless o[:block]
414   o[:class] = self[:orig_class] if self[:orig_class]
415 
416   "#<#{self.class} #{self[:model]}.#{self[:type]} #{self[:name].inspect}#{", #{o.inspect[1...-1]}" unless o.empty?}>"
417 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
420 def limit_and_offset
421   if (v = self[:limit]).is_a?(Array)
422     v
423   else
424     [v, nil]
425   end
426 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
430 def need_associated_primary_key?
431   false
432 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
436 def placeholder_loader
437   if use_placeholder_loader?
438     cached_fetch(:placeholder_loader) do
439       Sequel::Dataset::PlaceholderLiteralizer.loader(associated_dataset) do |pl, ds|
440         ds = ds.where(Sequel.&(*predicate_keys.map{|k| SQL::BooleanExpression.new(:'=', k, pl.arg)}))
441         if self[:block]
442           ds = self[:block].call(ds)
443         end
444         ds
445       end
446     end
447   end
448 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
456 def predicate_key_values(object)
457   predicate_key_methods.map{|k| object.get_column_value(k)}
458 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
451 def predicate_keys
452   cached_fetch(:predicate_keys){Array(predicate_key)}
453 end
qualify(table, col) click to toggle source

Qualify col with the given table name.

    # File lib/sequel/model/associations.rb
461 def qualify(table, col)
462   transform(col) do |k|
463     case k
464     when Symbol, SQL::Identifier
465       SQL::QualifiedIdentifier.new(table, k)
466     else
467       Sequel::Qualifier.new(table).transform(k)
468     end
469   end
470 end
qualify_assoc(col) click to toggle source

Qualify col with the associated model's table name.

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

Qualify col with the current model's table name.

    # File lib/sequel/model/associations.rb
478 def qualify_cur(col)
479   qualify(self[:model].table_name, col)
480 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
488 def reciprocal
489   cached_fetch(:reciprocal) do
490     possible_recips = []
491 
492     associated_class.all_association_reflections.each do |assoc_reflect|
493       if reciprocal_association?(assoc_reflect)
494         possible_recips << assoc_reflect
495       end
496     end
497 
498     if possible_recips.length == 1
499       cached_set(:reciprocal_type, possible_recips.first[:type]) if ambiguous_reciprocal_type?
500       possible_recips.first[:name]
501     end
502   end
503 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
507 def reciprocal_array?
508   true
509 end
remove_all_method() click to toggle source

Name symbol for the remove_all_ association method

    # File lib/sequel/model/associations.rb
512 def remove_all_method
513   self[:remove_all_method]
514 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
518 def remove_before_destroy?
519   true
520 end
remove_method() click to toggle source

Name symbol for the remove_ association method

    # File lib/sequel/model/associations.rb
523 def remove_method
524   self[:remove_method]
525 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
528 def remove_should_check_existing?
529   false
530 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
534 def returns_array?
535   true
536 end
select() click to toggle source

The columns to select when loading the association.

    # File lib/sequel/model/associations.rb
539 def select
540   self[:select]
541 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
545 def set_reciprocal_to_self?
546   false
547 end
setter_method() click to toggle source

Name symbol for the setter association method

    # File lib/sequel/model/associations.rb
550 def setter_method
551   self[:setter_method]
552 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
555 def slice_range(limit_and_offset = limit_and_offset())
556   limit, offset = limit_and_offset
557   if limit || offset
558     (offset||0)..(limit ? (offset||0)+limit-1 : -1)
559   end
560 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
585 def _associated_dataset
586   associated_class.dataset
587 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
591 def ambiguous_reciprocal_type?
592   false
593 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
611 def apply_filter_by_associations_distinct_on_limit_strategy(ds)
612   k = filter_by_associations_limit_key 
613   ds.where(k=>apply_distinct_on_eager_limit_strategy(associated_eager_dataset.select(*k)))
614 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
597 def apply_filter_by_associations_limit_strategy(ds)
598   case filter_by_associations_limit_strategy
599   when :distinct_on
600     apply_filter_by_associations_distinct_on_limit_strategy(ds)
601   when :window_function
602     apply_filter_by_associations_window_function_limit_strategy(ds)
603   else
604     ds
605   end
606 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
619 def apply_filter_by_associations_window_function_limit_strategy(ds)
620   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))
621 end
associated_eager_dataset() click to toggle source

The associated_dataset with the eager_block callback already applied.

    # File lib/sequel/model/associations.rb
624 def associated_eager_dataset
625   cached_fetch(:associated_eager_dataset) do
626     ds = associated_dataset.unlimited
627     if block = self[:eager_block]
628       ds = block.call(ds)
629     end
630     ds
631   end
632 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
568 def cached_fetch(key)
569   fetch(key) do
570     return yield unless h = self[:cache]
571     Sequel.synchronize{return h[key] if h.has_key?(key)}
572     value = yield
573     Sequel.synchronize{h[key] = value}
574   end
575 end
cached_set(key, value) click to toggle source

Cache the value at the given key if caching.

    # File lib/sequel/model/associations.rb
578 def cached_set(key, value)
579   return unless h = self[:cache]
580   Sequel.synchronize{h[key] = value}
581 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
663 def default_eager_limit_strategy
664   self[:model].default_eager_limit_strategy || :ruby
665 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
636 def eager_loading_dataset(eo=OPTS)
637   ds = eo[:dataset] || associated_eager_dataset
638   if id_map = eo[:id_map]
639     ds = ds.where(eager_loading_predicate_condition(id_map.keys))
640   end
641   if associations = eo[:associations]
642     ds = ds.eager(associations)
643   end
644   if block = eo[:eager_block]
645     orig_ds = ds
646     ds = block.call(ds)
647   end
648   if eager_loading_use_associated_key?
649     ds = if ds.opts[:eager_graph] && !orig_ds.opts[:eager_graph]
650       block.call(orig_ds.select_append(*associated_key_array))
651     else
652       ds.select_append(*associated_key_array)
653     end
654   end
655   if self[:eager_graph]
656     raise(Error, "cannot eagerly load a #{self[:type]} association that uses :eager_graph") if eager_loading_use_associated_key?
657     ds = ds.eager_graph(self[:eager_graph])
658   end
659   ds
660 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
668 def eager_loading_predicate_condition(keys)
669   {predicate_key=>keys}
670 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
674 def filter_by_associations_add_conditions_dataset_filter(ds)
675   k = filter_by_associations_conditions_associated_keys
676   ds.select(*k).where(Sequel.negate(k.zip([])))
677 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
697 def filter_by_associations_conditions_dataset
698   cached_fetch(:filter_by_associations_conditions_dataset) do
699     ds = associated_eager_dataset.unordered
700     ds = filter_by_associations_add_conditions_dataset_filter(ds)
701     ds = apply_filter_by_associations_limit_strategy(ds)
702     ds
703   end
704 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
682 def filter_by_associations_conditions_subquery_conditions(obj)
683   key = qualify(associated_class.table_name, associated_class.primary_key)
684   case obj
685   when Array
686     {key=>obj.map(&:pk)}
687   when Sequel::Dataset
688     {key=>obj.select(*Array(qualify(associated_class.table_name, associated_class.primary_key)))}
689   else
690     Array(key).zip(Array(obj.pk))
691   end
692 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
707 def filter_by_associations_limit_strategy
708   v = fetch(:filter_limit_strategy, self[:eager_limit_strategy])
709   if v || self[:limit] || !returns_array?
710     case v ||= self[:model].default_eager_limit_strategy
711     when true, :union, :ruby
712       # Can't use a union or ruby-based strategy for filtering by associations, switch to default eager graph limit
713       # strategy.
714       true_eager_graph_limit_strategy
715     when Symbol
716       v
717     end
718   end
719 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
722 def limit_to_single_row?
723   !returns_array?
724 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
727 def offset
728   limit_and_offset.last
729 end
placeholder_eager_loader() click to toggle source

A placeholder literalizer used to speed up eager loading.

    # File lib/sequel/model/associations.rb
732 def placeholder_eager_loader
733   cached_fetch(:placeholder_eager_loader) do
734     Sequel::Dataset::PlaceholderLiteralizer.loader(associated_dataset) do |pl, ds|
735       apply_eager_limit_strategy(eager_loading_dataset.where(predicate_key=>pl.arg), eager_limit_strategy)
736     end
737   end
738 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
742 def possible_reciprocal_types
743   [reciprocal_type]
744 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
748 def reciprocal_association?(assoc_reflect)
749   possible_reciprocal_types.include?(assoc_reflect[:type]) &&
750     (begin; assoc_reflect.associated_class; rescue NameError; end) == self[:model] &&
751     assoc_reflect[:conditions].nil? &&
752     assoc_reflect[:block].nil?
753 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
758 def subqueries_per_union
759   self[:subqueries_per_union] || 40
760 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
764 def transform(s, &block)
765   s.is_a?(Array) ? s.map(&block) : (yield s)
766 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
782 def true_eager_graph_limit_strategy
783   if associated_class.dataset.supports_window_functions?
784     :window_function
785   else
786     :ruby
787   end
788 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
770 def true_eager_limit_strategy
771   if self[:eager_graph] || (offset && !associated_dataset.supports_offsets_in_correlated_subqueries?)
772     # An SQL-based approach won't work if you are also eager graphing,
773     # so use a ruby based approach in that case.
774     :ruby
775   else
776     :union 
777   end
778 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
792 def union_eager_loader
793   cached_fetch(:union_eager_loader) do
794     Sequel::Dataset::PlaceholderLiteralizer.loader(associated_dataset) do |pl, ds|
795       ds = self[:eager_block].call(ds) if self[:eager_block]
796       keys = predicate_keys
797       ds = ds.where(keys.map{pl.arg}.zip(keys))
798       if eager_loading_use_associated_key?
799         ds = ds.select_append(*associated_key_array)
800       end
801       ds.from_self
802     end
803   end
804 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
807 def use_placeholder_loader?
808   self[:use_placeholder_loader]
809 end