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
Name symbol for the _add internal association method
# File lib/sequel/model/associations.rb 36 def _add_method 37 self[:_add_method] 38 end
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
Name symbol for the _remove internal association method
# File lib/sequel/model/associations.rb 46 def _remove_method 47 self[:_remove_method] 48 end
Name symbol for the _setter association method
# File lib/sequel/model/associations.rb 51 def _setter_method 52 self[:_setter_method] 53 end
Name symbol for the add association method
# File lib/sequel/model/associations.rb 56 def add_method 57 self[:add_method] 58 end
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
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 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 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 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
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
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
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
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
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
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
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
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
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
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
Name symbol for the dataset association method
# File lib/sequel/model/associations.rb 196 def dataset_method 197 self[:dataset_method] 198 end
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
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
Whether to eagerly graph a lazy dataset, true by default. If this is false, the association won't respect the :eager_graph option when loading the association for a single record.
# File lib/sequel/model/associations.rb 339 def eager_graph_lazy_dataset? 340 true 341 end
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
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 the associated objects using the hash of eager options, yielding each row to the block.
# File lib/sequel/model/associations.rb 264 def eager_load_results(eo, &block) 265 rows = eo[:rows] 266 unless eo[:initialize_rows] == false 267 Sequel.synchronize_with(eo[:mutex]){initialize_association_cache(rows)} 268 end 269 if eo[:id_map] 270 ids = eo[:id_map].keys 271 return ids if ids.empty? 272 end 273 strategy = eager_limit_strategy 274 cascade = eo[:associations] 275 eager_limit = nil 276 277 if eo[:no_results] 278 no_results = true 279 elsif eo[:eager_block] || eo[:loader] == false 280 ds = eager_loading_dataset(eo) 281 282 strategy = ds.opts[:eager_limit_strategy] || strategy 283 284 eager_limit = 285 if el = ds.opts[:eager_limit] 286 raise Error, "The :eager_limit dataset option is not supported for associations returning a single record" unless returns_array? 287 strategy ||= true_eager_graph_limit_strategy 288 if el.is_a?(Array) 289 el 290 else 291 [el, nil] 292 end 293 else 294 limit_and_offset 295 end 296 297 strategy = true_eager_graph_limit_strategy if strategy == :union 298 # Correlated subqueries are not supported for regular eager loading 299 strategy = :ruby if strategy == :correlated_subquery 300 strategy = nil if strategy == :ruby && assign_singular? 301 objects = apply_eager_limit_strategy(ds, strategy, eager_limit).all 302 elsif strategy == :union 303 objects = [] 304 ds = associated_dataset 305 loader = union_eager_loader 306 joiner = " UNION ALL " 307 ids.each_slice(subqueries_per_union).each do |slice| 308 objects.concat(ds.with_sql(slice.map{|k| loader.sql(*k)}.join(joiner)).to_a) 309 end 310 ds = ds.eager(cascade) if cascade 311 ds.send(:post_load, objects) 312 else 313 loader = placeholder_eager_loader 314 loader = loader.with_dataset{|dataset| dataset.eager(cascade)} if cascade 315 objects = loader.all(ids) 316 end 317 318 Sequel.synchronize_with(eo[:mutex]){objects.each(&block)} unless no_results 319 320 if strategy == :ruby 321 apply_ruby_eager_limit_strategy(rows, eager_limit || limit_and_offset) 322 end 323 end
The key to use for the key hash when eager loading
# File lib/sequel/model/associations.rb 326 def eager_loader_key 327 self[:eager_loader_key] 328 end
By default associations do not need to select a key in an associated table to eagerly load.
# File lib/sequel/model/associations.rb 332 def eager_loading_use_associated_key? 333 false 334 end
Whether additional conditions should be added when using the filter by associations support.
# File lib/sequel/model/associations.rb 345 def filter_by_associations_add_conditions? 346 self[:conditions] || self[:eager_block] || self[:limit] 347 end
The expression to use for the additional conditions to be added for the filter by association support, when the association itself is filtered. Works by using a subquery to test that the objects passed also meet the association filter criteria.
# File lib/sequel/model/associations.rb 353 def filter_by_associations_conditions_expression(obj) 354 ds = filter_by_associations_conditions_dataset.where(filter_by_associations_conditions_subquery_conditions(obj)) 355 {filter_by_associations_conditions_key=>ds} 356 end
Finalize the association by first attempting to populate the thread-safe cache, and then transfering the thread-safe cache value to the association itself, so that a mutex is not needed to get the value.
# File lib/sequel/model/associations.rb 361 def finalize 362 return unless cache = self[:cache] 363 364 finalizer = proc do |meth, key| 365 next if has_key?(key) 366 367 # Allow calling private methods to make sure caching is done appropriately 368 send(meth) 369 self[key] = cache.delete(key) if cache.has_key?(key) 370 end 371 372 finalize_settings.each(&finalizer) 373 374 unless self[:instance_specific] 375 finalizer.call(:associated_eager_dataset, :associated_eager_dataset) 376 finalizer.call(:filter_by_associations_conditions_dataset, :filter_by_associations_conditions_dataset) 377 end 378 379 nil 380 end
# File lib/sequel/model/associations.rb 392 def finalize_settings 393 FINALIZE_SETTINGS 394 end
Whether to handle silent modification failure when adding/removing associated records, false by default.
# File lib/sequel/model/associations.rb 398 def handle_silent_modification_failure? 399 false 400 end
Initialize the associations cache for the current association for the given objects.
# File lib/sequel/model/associations.rb 403 def initialize_association_cache(objects) 404 name = self[:name] 405 if assign_singular? 406 objects.each{|object| object.associations[name] = nil} 407 else 408 objects.each{|object| object.associations[name] = []} 409 end 410 end
Show which type of reflection this is, and a guess at what code was used to create the association.
# File lib/sequel/model/associations.rb 414 def inspect 415 o = self[:orig_opts].dup 416 o.delete(:class) 417 o.delete(:class_name) 418 o.delete(:block) unless o[:block] 419 o[:class] = self[:orig_class] if self[:orig_class] 420 421 "#<#{self.class} #{self[:model]}.#{self[:type]} #{self[:name].inspect}#{", #{o.inspect[1...-1]}" unless o.empty?}>" 422 end
The limit and offset for this association (returned as a two element array).
# File lib/sequel/model/associations.rb 425 def limit_and_offset 426 if (v = self[:limit]).is_a?(Array) 427 v 428 else 429 [v, nil] 430 end 431 end
Whether the associated object needs a primary key to be added/removed, false by default.
# File lib/sequel/model/associations.rb 435 def need_associated_primary_key? 436 false 437 end
A placeholder literalizer that can be used to lazily load the association. If one can't be used, returns nil.
# File lib/sequel/model/associations.rb 441 def placeholder_loader 442 if use_placeholder_loader? 443 cached_fetch(:placeholder_loader) do 444 Sequel::Dataset::PlaceholderLiteralizer.loader(associated_dataset) do |pl, ds| 445 ds = ds.where(Sequel.&(*predicate_keys.map{|k| SQL::BooleanExpression.new(:'=', k, pl.arg)})) 446 if self[:block] 447 ds = self[:block].call(ds) 448 end 449 ds 450 end 451 end 452 end 453 end
The values that predicate_keys
should match for objects to be associated.
# File lib/sequel/model/associations.rb 461 def predicate_key_values(object) 462 predicate_key_methods.map{|k| object.get_column_value(k)} 463 end
The keys to use for loading of the regular dataset, as an array.
# File lib/sequel/model/associations.rb 456 def predicate_keys 457 cached_fetch(:predicate_keys){Array(predicate_key)} 458 end
Qualify col
with the given table name.
# File lib/sequel/model/associations.rb 466 def qualify(table, col) 467 transform(col) do |k| 468 case k 469 when Symbol, SQL::Identifier 470 SQL::QualifiedIdentifier.new(table, k) 471 else 472 Sequel::Qualifier.new(table).transform(k) 473 end 474 end 475 end
Qualify col with the associated model's table name.
# File lib/sequel/model/associations.rb 478 def qualify_assoc(col) 479 qualify(associated_class.table_name, col) 480 end
Qualify col with the current model's table name.
# File lib/sequel/model/associations.rb 483 def qualify_cur(col) 484 qualify(self[:model].table_name, col) 485 end
Returns the reciprocal association variable, if one exists. The reciprocal association is the association in the associated class that is the opposite of the current association. For example, Album.many_to_one :artist and Artist.one_to_many :albums are reciprocal associations. This information is to populate reciprocal associations. For example, when you do this_artist.add_album(album) it sets album.artist to this_artist.
# File lib/sequel/model/associations.rb 493 def reciprocal 494 cached_fetch(:reciprocal) do 495 possible_recips = [] 496 497 associated_class.all_association_reflections.each do |assoc_reflect| 498 if reciprocal_association?(assoc_reflect) 499 possible_recips << assoc_reflect 500 end 501 end 502 503 if possible_recips.length == 1 504 cached_set(:reciprocal_type, possible_recips.first[:type]) if ambiguous_reciprocal_type? 505 possible_recips.first[:name] 506 end 507 end 508 end
Whether the reciprocal of this association returns an array of objects instead of a single object, true by default.
# File lib/sequel/model/associations.rb 512 def reciprocal_array? 513 true 514 end
Name symbol for the remove_all_ association method
# File lib/sequel/model/associations.rb 517 def remove_all_method 518 self[:remove_all_method] 519 end
Whether associated objects need to be removed from the association before being destroyed in order to preserve referential integrity.
# File lib/sequel/model/associations.rb 523 def remove_before_destroy? 524 true 525 end
Name symbol for the remove_ association method
# File lib/sequel/model/associations.rb 528 def remove_method 529 self[:remove_method] 530 end
Whether to check that an object to be disassociated is already associated to this object, false by default.
# File lib/sequel/model/associations.rb 533 def remove_should_check_existing? 534 false 535 end
Whether this association returns an array of objects instead of a single object, true by default.
# File lib/sequel/model/associations.rb 539 def returns_array? 540 true 541 end
The columns to select when loading the association.
# File lib/sequel/model/associations.rb 544 def select 545 self[:select] 546 end
Whether to set the reciprocal association to self when loading associated records, false by default.
# File lib/sequel/model/associations.rb 550 def set_reciprocal_to_self? 551 false 552 end
Name symbol for the setter association method
# File lib/sequel/model/associations.rb 555 def setter_method 556 self[:setter_method] 557 end
The range used for slicing when using the :ruby eager limit strategy.
# File lib/sequel/model/associations.rb 560 def slice_range(limit_and_offset = limit_and_offset()) 561 limit, offset = limit_and_offset 562 if limit || offset 563 (offset||0)..(limit ? (offset||0)+limit-1 : -1) 564 end 565 end
Private Instance Methods
The base dataset used for the association, before any order/conditions options have been applied.
# File lib/sequel/model/associations.rb 590 def _associated_dataset 591 associated_class.dataset 592 end
Whether for the reciprocal type for the given association cannot be known in advantage, false by default.
# File lib/sequel/model/associations.rb 596 def ambiguous_reciprocal_type? 597 false 598 end
Apply a distinct on eager limit strategy using IN with a subquery that uses DISTINCT ON to ensure only the first matching record for each key is included.
# File lib/sequel/model/associations.rb 616 def apply_filter_by_associations_distinct_on_limit_strategy(ds) 617 k = filter_by_associations_limit_key 618 ds.where(k=>apply_distinct_on_eager_limit_strategy(associated_eager_dataset.select(*k))) 619 end
Apply a limit strategy to the given dataset so that filter by associations works with a limited dataset.
# File lib/sequel/model/associations.rb 602 def apply_filter_by_associations_limit_strategy(ds) 603 case filter_by_associations_limit_strategy 604 when :distinct_on 605 apply_filter_by_associations_distinct_on_limit_strategy(ds) 606 when :window_function 607 apply_filter_by_associations_window_function_limit_strategy(ds) 608 else 609 ds 610 end 611 end
Apply a distinct on eager limit strategy using IN with a subquery that uses a filter on the row_number window function to ensure that only rows inside the limit are returned.
# File lib/sequel/model/associations.rb 624 def apply_filter_by_associations_window_function_limit_strategy(ds) 625 ds.where(filter_by_associations_limit_key=>apply_window_function_eager_limit_strategy(associated_eager_dataset.select(*filter_by_associations_limit_alias_key)).select(*filter_by_associations_limit_aliases)) 626 end
The associated_dataset
with the eager_block callback already applied.
# File lib/sequel/model/associations.rb 629 def associated_eager_dataset 630 cached_fetch(:associated_eager_dataset) do 631 ds = associated_dataset.unlimited 632 if block = self[:eager_block] 633 ds = block.call(ds) 634 end 635 ds 636 end 637 end
If the key exists in the reflection hash, return it. If the key doesn't exist and association reflections are uncached, then yield to get the value. If the key doesn't exist and association reflection are cached, check the cache and return the value if present, or yield to get the value, cache the value, and return it.
# File lib/sequel/model/associations.rb 573 def cached_fetch(key) 574 fetch(key) do 575 return yield unless h = self[:cache] 576 Sequel.synchronize{return h[key] if h.has_key?(key)} 577 value = yield 578 Sequel.synchronize{h[key] = value} 579 end 580 end
Cache the value at the given key if caching.
# File lib/sequel/model/associations.rb 583 def cached_set(key, value) 584 return unless h = self[:cache] 585 Sequel.synchronize{h[key] = value} 586 end
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
The dataset to use for eager loading associated objects for multiple current objects, given the hash passed to the eager loader.
# File lib/sequel/model/associations.rb 641 def eager_loading_dataset(eo=OPTS) 642 ds = eo[:dataset] || associated_eager_dataset 643 ds = eager_loading_set_predicate_condition(ds, eo) 644 if associations = eo[:associations] 645 ds = ds.eager(associations) 646 end 647 if block = eo[:eager_block] 648 orig_ds = ds 649 ds = block.call(ds) 650 end 651 if eager_loading_use_associated_key? 652 ds = if ds.opts[:eager_graph] && !orig_ds.opts[:eager_graph] 653 block.call(orig_ds.select_append(*associated_key_array)) 654 else 655 ds.select_append(*associated_key_array) 656 end 657 end 658 if self[:eager_graph] 659 raise(Error, "cannot eagerly load a #{self[:type]} association that uses :eager_graph") if eager_loading_use_associated_key? 660 ds = ds.eager_graph(self[:eager_graph]) 661 end 662 ds 663 end
The predicate condition to use for the eager_loader.
# File lib/sequel/model/associations.rb 680 def eager_loading_predicate_condition(keys) 681 {predicate_key=>keys} 682 end
Set the predicate condition for the eager loading dataset based on the id map in the eager loading options.
# File lib/sequel/model/associations.rb 672 def eager_loading_set_predicate_condition(ds, eo) 673 if id_map = eo[:id_map] 674 ds = ds.where(eager_loading_predicate_condition(id_map.keys)) 675 end 676 ds 677 end
Add conditions to the dataset to not include NULL values for the associated keys, and select those keys.
# File lib/sequel/model/associations.rb 686 def filter_by_associations_add_conditions_dataset_filter(ds) 687 k = filter_by_associations_conditions_associated_keys 688 ds.select(*k).where(Sequel.negate(k.zip([]))) 689 end
The base dataset to use for the filter by associations conditions subquery, regardless of the objects that are passed in as filter values.
# File lib/sequel/model/associations.rb 709 def filter_by_associations_conditions_dataset 710 cached_fetch(:filter_by_associations_conditions_dataset) do 711 ds = associated_eager_dataset.unordered 712 ds = filter_by_associations_add_conditions_dataset_filter(ds) 713 ds = apply_filter_by_associations_limit_strategy(ds) 714 ds 715 end 716 end
The conditions to add to the filter by associations conditions subquery to restrict it to to the object(s) that was used as the filter value.
# File lib/sequel/model/associations.rb 694 def filter_by_associations_conditions_subquery_conditions(obj) 695 key = qualify(associated_class.table_name, associated_class.primary_key) 696 case obj 697 when Array 698 {key=>obj.map(&:pk)} 699 when Sequel::Dataset 700 {key=>obj.select(*Array(qualify(associated_class.table_name, associated_class.primary_key)))} 701 else 702 Array(key).zip(Array(obj.pk)) 703 end 704 end
The strategy to use to filter by a limited association
# File lib/sequel/model/associations.rb 719 def filter_by_associations_limit_strategy 720 v = fetch(:filter_limit_strategy, self[:eager_limit_strategy]) 721 if v || self[:limit] || !returns_array? 722 case v ||= self[:model].default_eager_limit_strategy 723 when true, :union, :ruby 724 # Can't use a union or ruby-based strategy for filtering by associations, switch to default eager graph limit 725 # strategy. 726 true_eager_graph_limit_strategy 727 when Symbol 728 v 729 end 730 end 731 end
Whether to limit the associated dataset to a single row.
# File lib/sequel/model/associations.rb 734 def limit_to_single_row? 735 !returns_array? 736 end
Any offset to use for this association (or nil if there is no offset).
# File lib/sequel/model/associations.rb 739 def offset 740 limit_and_offset.last 741 end
A placeholder literalizer used to speed up eager loading.
# File lib/sequel/model/associations.rb 744 def placeholder_eager_loader 745 cached_fetch(:placeholder_eager_loader) do 746 Sequel::Dataset::PlaceholderLiteralizer.loader(associated_dataset) do |pl, ds| 747 apply_eager_limit_strategy(eager_loading_dataset.where(predicate_key=>pl.arg), eager_limit_strategy) 748 end 749 end 750 end
The reciprocal type as an array, should be overridden in reflection subclasses that have ambiguous reciprocal types.
# File lib/sequel/model/associations.rb 754 def possible_reciprocal_types 755 [reciprocal_type] 756 end
Whether the given association reflection is possible reciprocal association for the current association reflection.
# File lib/sequel/model/associations.rb 760 def reciprocal_association?(assoc_reflect) 761 possible_reciprocal_types.include?(assoc_reflect[:type]) && 762 (begin; assoc_reflect.associated_class; rescue NameError; end) == self[:model] && 763 assoc_reflect[:conditions].nil? && 764 assoc_reflect[:block].nil? 765 end
The number of subqueries to use in each union query, used to eagerly load limited associations. Defaults to 40, the optimal number depends on the latency between the database and the application.
# File lib/sequel/model/associations.rb 770 def subqueries_per_union 771 self[:subqueries_per_union] || 40 772 end
If s
is an array, map s
over the block. Otherwise, just call the block with s
.
# File lib/sequel/model/associations.rb 776 def transform(s, &block) 777 s.is_a?(Array) ? s.map(&block) : (yield s) 778 end
The eager_graph limit strategy used when true is given as the value, choosing the best strategy based on what the database supports.
# File lib/sequel/model/associations.rb 794 def true_eager_graph_limit_strategy 795 if associated_class.dataset.supports_window_functions? 796 :window_function 797 else 798 :ruby 799 end 800 end
What eager limit strategy should be used when true is given as the value, defaults to UNION as that is the fastest strategy if the appropriate keys are indexed.
# File lib/sequel/model/associations.rb 782 def true_eager_limit_strategy 783 if self[:eager_graph] || (offset && !associated_dataset.supports_offsets_in_correlated_subqueries?) 784 # An SQL-based approach won't work if you are also eager graphing, 785 # so use a ruby based approach in that case. 786 :ruby 787 else 788 :union 789 end 790 end
A placeholder literalizer used to speed up the creation of union queries when eager loading a limited association.
# File lib/sequel/model/associations.rb 804 def union_eager_loader 805 cached_fetch(:union_eager_loader) do 806 Sequel::Dataset::PlaceholderLiteralizer.loader(associated_dataset) do |pl, ds| 807 ds = self[:eager_block].call(ds) if self[:eager_block] 808 keys = predicate_keys 809 ds = ds.where(keys.map{pl.arg}.zip(keys)) 810 if eager_loading_use_associated_key? 811 ds = ds.select_append(*associated_key_array) 812 end 813 ds.from_self 814 end 815 end 816 end
Whether the placeholder loader can be used to load the association.
# File lib/sequel/model/associations.rb 819 def use_placeholder_loader? 820 self[:use_placeholder_loader] 821 end