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
344 def eager_graph_lazy_dataset?
345   true
346 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 || !use_placeholder_loader?
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 
303     if strategy == :window_function
304       delete_rn = ds.row_number_column 
305       objects.each{|obj| obj.values.delete(delete_rn)}
306     end
307   elsif strategy == :union
308     objects = []
309     ds = associated_dataset
310     loader = union_eager_loader
311     joiner = " UNION ALL "
312     ids.each_slice(subqueries_per_union).each do |slice|
313       objects.concat(ds.with_sql(slice.map{|k| loader.sql(*k)}.join(joiner)).to_a)
314     end
315     ds = ds.eager(cascade) if cascade
316     ds.send(:post_load, objects)
317   else
318     loader = placeholder_eager_loader
319     loader = loader.with_dataset{|dataset| dataset.eager(cascade)} if cascade
320     objects = loader.all(ids)
321   end
322 
323   Sequel.synchronize_with(eo[:mutex]){objects.each(&block)} unless no_results
324 
325   if strategy == :ruby
326     apply_ruby_eager_limit_strategy(rows, eager_limit || limit_and_offset)
327   end
328 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
331 def eager_loader_key
332   self[:eager_loader_key]
333 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
337 def eager_loading_use_associated_key?
338   false
339 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
350 def filter_by_associations_add_conditions?
351   self[:conditions] || self[:eager_block] || self[:limit]
352 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
358 def filter_by_associations_conditions_expression(obj)
359   ds = filter_by_associations_conditions_dataset.where(filter_by_associations_conditions_subquery_conditions(obj))
360   {filter_by_associations_conditions_key=>ds}
361 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
366 def finalize
367   return unless cache = self[:cache]
368 
369   finalizer = proc do |meth, key|
370     next if has_key?(key)
371 
372     # Allow calling private methods to make sure caching is done appropriately
373     send(meth)
374     self[key] = cache.delete(key) if cache.has_key?(key)
375   end
376 
377   finalize_settings.each(&finalizer)
378 
379   unless self[:instance_specific]
380     finalizer.call(:associated_eager_dataset, :associated_eager_dataset)
381     finalizer.call(:filter_by_associations_conditions_dataset, :filter_by_associations_conditions_dataset)
382   end
383 
384   nil
385 end
finalize_settings() click to toggle source
    # File lib/sequel/model/associations.rb
397 def finalize_settings
398   FINALIZE_SETTINGS
399 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
403 def handle_silent_modification_failure?
404   false
405 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
408 def initialize_association_cache(objects)
409   name = self[:name]
410   if assign_singular?
411     objects.each{|object| object.associations[name] = nil}
412   else
413     objects.each{|object| object.associations[name] = []}
414   end
415 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
419 def inspect
420   o = self[:orig_opts].dup
421   o.delete(:class)
422   o.delete(:class_name)
423   o.delete(:block) unless o[:block]
424   o[:class] = self[:orig_class] if self[:orig_class]
425 
426   "#<#{self.class} #{self[:model]}.#{self[:type]} #{self[:name].inspect}#{", #{o.inspect[1...-1]}" unless o.empty?}>"
427 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
430 def limit_and_offset
431   if (v = self[:limit]).is_a?(Array)
432     v
433   else
434     [v, nil]
435   end
436 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
440 def need_associated_primary_key?
441   false
442 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
446 def placeholder_loader
447   if use_placeholder_loader?
448     cached_fetch(:placeholder_loader) do
449       Sequel::Dataset::PlaceholderLiteralizer.loader(associated_dataset) do |pl, ds|
450         ds = ds.where(Sequel.&(*predicate_keys.map{|k| SQL::BooleanExpression.new(:'=', k, pl.arg)}))
451         if self[:block]
452           ds = self[:block].call(ds)
453         end
454         ds
455       end
456     end
457   end
458 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
466 def predicate_key_values(object)
467   predicate_key_methods.map{|k| object.get_column_value(k)}
468 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
461 def predicate_keys
462   cached_fetch(:predicate_keys){Array(predicate_key)}
463 end
qualify(table, col) click to toggle source

Qualify col with the given table name.

    # File lib/sequel/model/associations.rb
471 def qualify(table, col)
472   transform(col) do |k|
473     case k
474     when Symbol, SQL::Identifier
475       SQL::QualifiedIdentifier.new(table, k)
476     else
477       Sequel::Qualifier.new(table).transform(k)
478     end
479   end
480 end
qualify_assoc(col) click to toggle source

Qualify col with the associated model's table name.

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

Qualify col with the current model's table name.

    # File lib/sequel/model/associations.rb
488 def qualify_cur(col)
489   qualify(self[:model].table_name, col)
490 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
498 def reciprocal
499   cached_fetch(:reciprocal) do
500     possible_recips = []
501 
502     associated_class.all_association_reflections.each do |assoc_reflect|
503       if reciprocal_association?(assoc_reflect)
504         possible_recips << assoc_reflect
505       end
506     end
507 
508     if possible_recips.length == 1
509       cached_set(:reciprocal_type, possible_recips.first[:type]) if ambiguous_reciprocal_type?
510       possible_recips.first[:name]
511     end
512   end
513 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
517 def reciprocal_array?
518   true
519 end
remove_all_method() click to toggle source

Name symbol for the remove_all_ association method

    # File lib/sequel/model/associations.rb
522 def remove_all_method
523   self[:remove_all_method]
524 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
528 def remove_before_destroy?
529   true
530 end
remove_method() click to toggle source

Name symbol for the remove_ association method

    # File lib/sequel/model/associations.rb
533 def remove_method
534   self[:remove_method]
535 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
538 def remove_should_check_existing?
539   false
540 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
544 def returns_array?
545   true
546 end
select() click to toggle source

The columns to select when loading the association.

    # File lib/sequel/model/associations.rb
549 def select
550   self[:select]
551 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
555 def set_reciprocal_to_self?
556   false
557 end
setter_method() click to toggle source

Name symbol for the setter association method

    # File lib/sequel/model/associations.rb
560 def setter_method
561   self[:setter_method]
562 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
565 def slice_range(limit_and_offset = limit_and_offset())
566   limit, offset = limit_and_offset
567   if limit || offset
568     (offset||0)..(limit ? (offset||0)+limit-1 : -1)
569   end
570 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
595 def _associated_dataset
596   associated_class.dataset
597 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
601 def ambiguous_reciprocal_type?
602   false
603 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
621 def apply_filter_by_associations_distinct_on_limit_strategy(ds)
622   k = filter_by_associations_limit_key 
623   ds.where(k=>apply_distinct_on_eager_limit_strategy(associated_eager_dataset.select(*k)))
624 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
607 def apply_filter_by_associations_limit_strategy(ds)
608   case filter_by_associations_limit_strategy
609   when :distinct_on
610     apply_filter_by_associations_distinct_on_limit_strategy(ds)
611   when :window_function
612     apply_filter_by_associations_window_function_limit_strategy(ds)
613   else
614     ds
615   end
616 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
629 def apply_filter_by_associations_window_function_limit_strategy(ds)
630   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))
631 end
associated_eager_dataset() click to toggle source

The associated_dataset with the eager_block callback already applied.

    # File lib/sequel/model/associations.rb
634 def associated_eager_dataset
635   cached_fetch(:associated_eager_dataset) do
636     ds = associated_dataset.unlimited
637     if block = self[:eager_block]
638       ds = block.call(ds)
639     end
640     ds
641   end
642 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
578 def cached_fetch(key)
579   fetch(key) do
580     return yield unless h = self[:cache]
581     Sequel.synchronize{return h[key] if h.has_key?(key)}
582     value = yield
583     Sequel.synchronize{h[key] = value}
584   end
585 end
cached_set(key, value) click to toggle source

Cache the value at the given key if caching.

    # File lib/sequel/model/associations.rb
588 def cached_set(key, value)
589   return unless h = self[:cache]
590   Sequel.synchronize{h[key] = value}
591 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
671 def default_eager_limit_strategy
672   self[:model].default_eager_limit_strategy || :ruby
673 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
646 def eager_loading_dataset(eo=OPTS)
647   ds = eo[:dataset] || associated_eager_dataset
648   ds = eager_loading_set_predicate_condition(ds, eo)
649   if associations = eo[:associations]
650     ds = ds.eager(associations)
651   end
652   if block = eo[:eager_block]
653     orig_ds = ds
654     ds = block.call(ds)
655   end
656   if eager_loading_use_associated_key?
657     ds = if ds.opts[:eager_graph] && !orig_ds.opts[:eager_graph]
658       block.call(orig_ds.select_append(*associated_key_array))
659     else
660       ds.select_append(*associated_key_array)
661     end
662   end
663   if self[:eager_graph]
664     raise(Error, "cannot eagerly load a #{self[:type]} association that uses :eager_graph") if eager_loading_use_associated_key?
665     ds = ds.eager_graph(self[:eager_graph])
666   end
667   ds
668 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
685 def eager_loading_predicate_condition(keys)
686   {predicate_key=>keys}
687 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
677 def eager_loading_set_predicate_condition(ds, eo)
678   if id_map = eo[:id_map]
679     ds = ds.where(eager_loading_predicate_condition(id_map.keys))
680   end
681   ds
682 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
691 def filter_by_associations_add_conditions_dataset_filter(ds)
692   k = filter_by_associations_conditions_associated_keys
693   ds.select(*k).where(Sequel.negate(k.zip([])))
694 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
714 def filter_by_associations_conditions_dataset
715   cached_fetch(:filter_by_associations_conditions_dataset) do
716     ds = associated_eager_dataset.unordered
717     ds = filter_by_associations_add_conditions_dataset_filter(ds)
718     ds = apply_filter_by_associations_limit_strategy(ds)
719     ds
720   end
721 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
699 def filter_by_associations_conditions_subquery_conditions(obj)
700   key = qualify(associated_class.table_name, associated_class.primary_key)
701   case obj
702   when Array
703     {key=>obj.map(&:pk)}
704   when Sequel::Dataset
705     {key=>obj.select(*Array(qualify(associated_class.table_name, associated_class.primary_key)))}
706   else
707     Array(key).zip(Array(obj.pk))
708   end
709 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
724 def filter_by_associations_limit_strategy
725   v = fetch(:filter_limit_strategy, self[:eager_limit_strategy])
726   if v || self[:limit] || !returns_array?
727     case v ||= self[:model].default_eager_limit_strategy
728     when true, :union, :ruby
729       # Can't use a union or ruby-based strategy for filtering by associations, switch to default eager graph limit
730       # strategy.
731       true_eager_graph_limit_strategy
732     when Symbol
733       v
734     end
735   end
736 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
739 def limit_to_single_row?
740   !returns_array?
741 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
744 def offset
745   limit_and_offset.last
746 end
placeholder_eager_loader() click to toggle source

A placeholder literalizer used to speed up eager loading.

    # File lib/sequel/model/associations.rb
749 def placeholder_eager_loader
750   cached_fetch(:placeholder_eager_loader) do
751     Sequel::Dataset::PlaceholderLiteralizer.loader(associated_dataset) do |pl, ds|
752       apply_eager_limit_strategy(eager_loading_dataset.where(predicate_key=>pl.arg), eager_limit_strategy)
753     end
754   end
755 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
759 def possible_reciprocal_types
760   [reciprocal_type]
761 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
765 def reciprocal_association?(assoc_reflect)
766   possible_reciprocal_types.include?(assoc_reflect[:type]) &&
767     (begin; assoc_reflect.associated_class; rescue NameError; end) == self[:model] &&
768     assoc_reflect[:conditions].nil? &&
769     assoc_reflect[:block].nil?
770 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
775 def subqueries_per_union
776   self[:subqueries_per_union] || 40
777 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
781 def transform(s, &block)
782   s.is_a?(Array) ? s.map(&block) : (yield s)
783 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
799 def true_eager_graph_limit_strategy
800   if associated_class.dataset.supports_window_functions?
801     :window_function
802   else
803     :ruby
804   end
805 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
787 def true_eager_limit_strategy
788   if self[:eager_graph] || (offset && !associated_dataset.supports_offsets_in_correlated_subqueries?)
789     # An SQL-based approach won't work if you are also eager graphing,
790     # so use a ruby based approach in that case.
791     :ruby
792   else
793     :union 
794   end
795 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
809 def union_eager_loader
810   cached_fetch(:union_eager_loader) do
811     Sequel::Dataset::PlaceholderLiteralizer.loader(associated_dataset) do |pl, ds|
812       ds = self[:eager_block].call(ds) if self[:eager_block]
813       keys = predicate_keys
814       ds = ds.where(keys.map{pl.arg}.zip(keys))
815       if eager_loading_use_associated_key?
816         ds = ds.select_append(*associated_key_array)
817       end
818       ds.from_self
819     end
820   end
821 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
824 def use_placeholder_loader?
825   self[:use_placeholder_loader] && _associated_dataset.supports_placeholder_literalizer?
826 end