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
337 def eager_graph_lazy_dataset?
338   true
339 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[:eager_block] || eo[:loader] == false
278     ds = eager_loading_dataset(eo)
279 
280     strategy = ds.opts[:eager_limit_strategy] || strategy
281 
282     eager_limit =
283       if el = ds.opts[:eager_limit]
284         raise Error, "The :eager_limit dataset option is not supported for associations returning a single record" unless returns_array?
285         strategy ||= true_eager_graph_limit_strategy
286         if el.is_a?(Array)
287           el
288         else
289           [el, nil]
290         end
291       else
292         limit_and_offset
293       end
294 
295     strategy = true_eager_graph_limit_strategy if strategy == :union
296     # Correlated subqueries are not supported for regular eager loading
297     strategy = :ruby if strategy == :correlated_subquery
298     strategy = nil if strategy == :ruby && assign_singular?
299     objects = apply_eager_limit_strategy(ds, strategy, eager_limit).all
300   elsif strategy == :union
301     objects = []
302     ds = associated_dataset
303     loader = union_eager_loader
304     joiner = " UNION ALL "
305     ids.each_slice(subqueries_per_union).each do |slice|
306       objects.concat(ds.with_sql(slice.map{|k| loader.sql(*k)}.join(joiner)).to_a)
307     end
308     ds = ds.eager(cascade) if cascade
309     ds.send(:post_load, objects)
310   else
311     loader = placeholder_eager_loader
312     loader = loader.with_dataset{|dataset| dataset.eager(cascade)} if cascade
313     objects = loader.all(ids)
314   end
315 
316   Sequel.synchronize_with(eo[:mutex]){objects.each(&block)}
317 
318   if strategy == :ruby
319     apply_ruby_eager_limit_strategy(rows, eager_limit || limit_and_offset)
320   end
321 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
324 def eager_loader_key
325   self[:eager_loader_key]
326 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
330 def eager_loading_use_associated_key?
331   false
332 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
343 def filter_by_associations_add_conditions?
344   self[:conditions] || self[:eager_block] || self[:limit]
345 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
351 def filter_by_associations_conditions_expression(obj)
352   ds = filter_by_associations_conditions_dataset.where(filter_by_associations_conditions_subquery_conditions(obj))
353   {filter_by_associations_conditions_key=>ds}
354 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
359 def finalize
360   return unless cache = self[:cache]
361 
362   finalizer = proc do |meth, key|
363     next if has_key?(key)
364 
365     # Allow calling private methods to make sure caching is done appropriately
366     send(meth)
367     self[key] = cache.delete(key) if cache.has_key?(key)
368   end
369 
370   finalize_settings.each(&finalizer)
371 
372   unless self[:instance_specific]
373     finalizer.call(:associated_eager_dataset, :associated_eager_dataset)
374     finalizer.call(:filter_by_associations_conditions_dataset, :filter_by_associations_conditions_dataset)
375   end
376 
377   nil
378 end
finalize_settings() click to toggle source
    # File lib/sequel/model/associations.rb
390 def finalize_settings
391   FINALIZE_SETTINGS
392 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
396 def handle_silent_modification_failure?
397   false
398 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
401 def initialize_association_cache(objects)
402   name = self[:name]
403   if assign_singular?
404     objects.each{|object| object.associations[name] = nil}
405   else
406     objects.each{|object| object.associations[name] = []}
407   end
408 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
412 def inspect
413   o = self[:orig_opts].dup
414   o.delete(:class)
415   o.delete(:class_name)
416   o.delete(:block) unless o[:block]
417   o[:class] = self[:orig_class] if self[:orig_class]
418 
419   "#<#{self.class} #{self[:model]}.#{self[:type]} #{self[:name].inspect}#{", #{o.inspect[1...-1]}" unless o.empty?}>"
420 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
423 def limit_and_offset
424   if (v = self[:limit]).is_a?(Array)
425     v
426   else
427     [v, nil]
428   end
429 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
433 def need_associated_primary_key?
434   false
435 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
439 def placeholder_loader
440   if use_placeholder_loader?
441     cached_fetch(:placeholder_loader) do
442       Sequel::Dataset::PlaceholderLiteralizer.loader(associated_dataset) do |pl, ds|
443         ds = ds.where(Sequel.&(*predicate_keys.map{|k| SQL::BooleanExpression.new(:'=', k, pl.arg)}))
444         if self[:block]
445           ds = self[:block].call(ds)
446         end
447         ds
448       end
449     end
450   end
451 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
459 def predicate_key_values(object)
460   predicate_key_methods.map{|k| object.get_column_value(k)}
461 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
454 def predicate_keys
455   cached_fetch(:predicate_keys){Array(predicate_key)}
456 end
qualify(table, col) click to toggle source

Qualify col with the given table name.

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

Qualify col with the associated model's table name.

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

Qualify col with the current model's table name.

    # File lib/sequel/model/associations.rb
481 def qualify_cur(col)
482   qualify(self[:model].table_name, col)
483 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
491 def reciprocal
492   cached_fetch(:reciprocal) do
493     possible_recips = []
494 
495     associated_class.all_association_reflections.each do |assoc_reflect|
496       if reciprocal_association?(assoc_reflect)
497         possible_recips << assoc_reflect
498       end
499     end
500 
501     if possible_recips.length == 1
502       cached_set(:reciprocal_type, possible_recips.first[:type]) if ambiguous_reciprocal_type?
503       possible_recips.first[:name]
504     end
505   end
506 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
510 def reciprocal_array?
511   true
512 end
remove_all_method() click to toggle source

Name symbol for the remove_all_ association method

    # File lib/sequel/model/associations.rb
515 def remove_all_method
516   self[:remove_all_method]
517 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
521 def remove_before_destroy?
522   true
523 end
remove_method() click to toggle source

Name symbol for the remove_ association method

    # File lib/sequel/model/associations.rb
526 def remove_method
527   self[:remove_method]
528 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
531 def remove_should_check_existing?
532   false
533 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
537 def returns_array?
538   true
539 end
select() click to toggle source

The columns to select when loading the association.

    # File lib/sequel/model/associations.rb
542 def select
543   self[:select]
544 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
548 def set_reciprocal_to_self?
549   false
550 end
setter_method() click to toggle source

Name symbol for the setter association method

    # File lib/sequel/model/associations.rb
553 def setter_method
554   self[:setter_method]
555 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
558 def slice_range(limit_and_offset = limit_and_offset())
559   limit, offset = limit_and_offset
560   if limit || offset
561     (offset||0)..(limit ? (offset||0)+limit-1 : -1)
562   end
563 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
588 def _associated_dataset
589   associated_class.dataset
590 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
594 def ambiguous_reciprocal_type?
595   false
596 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
614 def apply_filter_by_associations_distinct_on_limit_strategy(ds)
615   k = filter_by_associations_limit_key 
616   ds.where(k=>apply_distinct_on_eager_limit_strategy(associated_eager_dataset.select(*k)))
617 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
600 def apply_filter_by_associations_limit_strategy(ds)
601   case filter_by_associations_limit_strategy
602   when :distinct_on
603     apply_filter_by_associations_distinct_on_limit_strategy(ds)
604   when :window_function
605     apply_filter_by_associations_window_function_limit_strategy(ds)
606   else
607     ds
608   end
609 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
622 def apply_filter_by_associations_window_function_limit_strategy(ds)
623   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))
624 end
associated_eager_dataset() click to toggle source

The associated_dataset with the eager_block callback already applied.

    # File lib/sequel/model/associations.rb
627 def associated_eager_dataset
628   cached_fetch(:associated_eager_dataset) do
629     ds = associated_dataset.unlimited
630     if block = self[:eager_block]
631       ds = block.call(ds)
632     end
633     ds
634   end
635 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
571 def cached_fetch(key)
572   fetch(key) do
573     return yield unless h = self[:cache]
574     Sequel.synchronize{return h[key] if h.has_key?(key)}
575     value = yield
576     Sequel.synchronize{h[key] = value}
577   end
578 end
cached_set(key, value) click to toggle source

Cache the value at the given key if caching.

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

The default eager limit strategy to use for this association

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

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

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

The predicate condition to use for the eager_loader.

    # File lib/sequel/model/associations.rb
671 def eager_loading_predicate_condition(keys)
672   {predicate_key=>keys}
673 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
677 def filter_by_associations_add_conditions_dataset_filter(ds)
678   k = filter_by_associations_conditions_associated_keys
679   ds.select(*k).where(Sequel.negate(k.zip([])))
680 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
700 def filter_by_associations_conditions_dataset
701   cached_fetch(:filter_by_associations_conditions_dataset) do
702     ds = associated_eager_dataset.unordered
703     ds = filter_by_associations_add_conditions_dataset_filter(ds)
704     ds = apply_filter_by_associations_limit_strategy(ds)
705     ds
706   end
707 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
685 def filter_by_associations_conditions_subquery_conditions(obj)
686   key = qualify(associated_class.table_name, associated_class.primary_key)
687   case obj
688   when Array
689     {key=>obj.map(&:pk)}
690   when Sequel::Dataset
691     {key=>obj.select(*Array(qualify(associated_class.table_name, associated_class.primary_key)))}
692   else
693     Array(key).zip(Array(obj.pk))
694   end
695 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
710 def filter_by_associations_limit_strategy
711   v = fetch(:filter_limit_strategy, self[:eager_limit_strategy])
712   if v || self[:limit] || !returns_array?
713     case v ||= self[:model].default_eager_limit_strategy
714     when true, :union, :ruby
715       # Can't use a union or ruby-based strategy for filtering by associations, switch to default eager graph limit
716       # strategy.
717       true_eager_graph_limit_strategy
718     when Symbol
719       v
720     end
721   end
722 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
725 def limit_to_single_row?
726   !returns_array?
727 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
730 def offset
731   limit_and_offset.last
732 end
placeholder_eager_loader() click to toggle source

A placeholder literalizer used to speed up eager loading.

    # File lib/sequel/model/associations.rb
735 def placeholder_eager_loader
736   cached_fetch(:placeholder_eager_loader) do
737     Sequel::Dataset::PlaceholderLiteralizer.loader(associated_dataset) do |pl, ds|
738       apply_eager_limit_strategy(eager_loading_dataset.where(predicate_key=>pl.arg), eager_limit_strategy)
739     end
740   end
741 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
745 def possible_reciprocal_types
746   [reciprocal_type]
747 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
751 def reciprocal_association?(assoc_reflect)
752   possible_reciprocal_types.include?(assoc_reflect[:type]) &&
753     (begin; assoc_reflect.associated_class; rescue NameError; end) == self[:model] &&
754     assoc_reflect[:conditions].nil? &&
755     assoc_reflect[:block].nil?
756 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
761 def subqueries_per_union
762   self[:subqueries_per_union] || 40
763 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
767 def transform(s, &block)
768   s.is_a?(Array) ? s.map(&block) : (yield s)
769 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
785 def true_eager_graph_limit_strategy
786   if associated_class.dataset.supports_window_functions?
787     :window_function
788   else
789     :ruby
790   end
791 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
773 def true_eager_limit_strategy
774   if self[:eager_graph] || (offset && !associated_dataset.supports_offsets_in_correlated_subqueries?)
775     # An SQL-based approach won't work if you are also eager graphing,
776     # so use a ruby based approach in that case.
777     :ruby
778   else
779     :union 
780   end
781 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
795 def union_eager_loader
796   cached_fetch(:union_eager_loader) do
797     Sequel::Dataset::PlaceholderLiteralizer.loader(associated_dataset) do |pl, ds|
798       ds = self[:eager_block].call(ds) if self[:eager_block]
799       keys = predicate_keys
800       ds = ds.where(keys.map{pl.arg}.zip(keys))
801       if eager_loading_use_associated_key?
802         ds = ds.select_append(*associated_key_array)
803       end
804       ds.from_self
805     end
806   end
807 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
810 def use_placeholder_loader?
811   self[:use_placeholder_loader]
812 end