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 334 def eager_graph_lazy_dataset? 335 true 336 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 initialize_association_cache(rows) unless eo[:initialize_rows] == false 267 if eo[:id_map] 268 ids = eo[:id_map].keys 269 return ids if ids.empty? 270 end 271 strategy = eager_limit_strategy 272 cascade = eo[:associations] 273 eager_limit = nil 274 275 if eo[:eager_block] || eo[:loader] == false 276 ds = eager_loading_dataset(eo) 277 278 strategy = ds.opts[:eager_limit_strategy] || strategy 279 280 eager_limit = 281 if el = ds.opts[:eager_limit] 282 raise Error, "The :eager_limit dataset option is not supported for associations returning a single record" unless returns_array? 283 strategy ||= true_eager_graph_limit_strategy 284 if el.is_a?(Array) 285 el 286 else 287 [el, nil] 288 end 289 else 290 limit_and_offset 291 end 292 293 strategy = true_eager_graph_limit_strategy if strategy == :union 294 # Correlated subqueries are not supported for regular eager loading 295 strategy = :ruby if strategy == :correlated_subquery 296 strategy = nil if strategy == :ruby && assign_singular? 297 objects = apply_eager_limit_strategy(ds, strategy, eager_limit).all 298 elsif strategy == :union 299 objects = [] 300 ds = associated_dataset 301 loader = union_eager_loader 302 joiner = " UNION ALL " 303 ids.each_slice(subqueries_per_union).each do |slice| 304 objects.concat(ds.with_sql(slice.map{|k| loader.sql(*k)}.join(joiner)).to_a) 305 end 306 ds = ds.eager(cascade) if cascade 307 ds.send(:post_load, objects) 308 else 309 loader = placeholder_eager_loader 310 loader = loader.with_dataset{|dataset| dataset.eager(cascade)} if cascade 311 objects = loader.all(ids) 312 end 313 314 objects.each(&block) 315 if strategy == :ruby 316 apply_ruby_eager_limit_strategy(rows, eager_limit || limit_and_offset) 317 end 318 end
The key to use for the key hash when eager loading
# File lib/sequel/model/associations.rb 321 def eager_loader_key 322 self[:eager_loader_key] 323 end
By default associations do not need to select a key in an associated table to eagerly load.
# File lib/sequel/model/associations.rb 327 def eager_loading_use_associated_key? 328 false 329 end
Whether additional conditions should be added when using the filter by associations support.
# File lib/sequel/model/associations.rb 340 def filter_by_associations_add_conditions? 341 self[:conditions] || self[:eager_block] || self[:limit] 342 end
The expression to use for the additional conditions to be added for the filter by association support, when the association itself is filtered. Works by using a subquery to test that the objects passed also meet the association filter criteria.
# File lib/sequel/model/associations.rb 348 def filter_by_associations_conditions_expression(obj) 349 ds = filter_by_associations_conditions_dataset.where(filter_by_associations_conditions_subquery_conditions(obj)) 350 {filter_by_associations_conditions_key=>ds} 351 end
Finalize the association by first attempting to populate the thread-safe cache, and then transfering the thread-safe cache value to the association itself, so that a mutex is not needed to get the value.
# File lib/sequel/model/associations.rb 356 def finalize 357 return unless cache = self[:cache] 358 359 finalizer = proc do |meth, key| 360 next if has_key?(key) 361 362 # Allow calling private methods to make sure caching is done appropriately 363 send(meth) 364 self[key] = cache.delete(key) if cache.has_key?(key) 365 end 366 367 finalize_settings.each(&finalizer) 368 369 unless self[:instance_specific] 370 finalizer.call(:associated_eager_dataset, :associated_eager_dataset) 371 finalizer.call(:filter_by_associations_conditions_dataset, :filter_by_associations_conditions_dataset) 372 end 373 374 nil 375 end
# File lib/sequel/model/associations.rb 387 def finalize_settings 388 FINALIZE_SETTINGS 389 end
Whether to handle silent modification failure when adding/removing associated records, false by default.
# File lib/sequel/model/associations.rb 393 def handle_silent_modification_failure? 394 false 395 end
Initialize the associations cache for the current association for the given objects.
# File lib/sequel/model/associations.rb 398 def initialize_association_cache(objects) 399 name = self[:name] 400 if assign_singular? 401 objects.each{|object| object.associations[name] = nil} 402 else 403 objects.each{|object| object.associations[name] = []} 404 end 405 end
Show which type of reflection this is, and a guess at what code was used to create the association.
# File lib/sequel/model/associations.rb 409 def inspect 410 o = self[:orig_opts].dup 411 o.delete(:class) 412 o.delete(:class_name) 413 o.delete(:block) unless o[:block] 414 o[:class] = self[:orig_class] if self[:orig_class] 415 416 "#<#{self.class} #{self[:model]}.#{self[:type]} #{self[:name].inspect}#{", #{o.inspect[1...-1]}" unless o.empty?}>" 417 end
The limit and offset for this association (returned as a two element array).
# File lib/sequel/model/associations.rb 420 def limit_and_offset 421 if (v = self[:limit]).is_a?(Array) 422 v 423 else 424 [v, nil] 425 end 426 end
Whether the associated object needs a primary key to be added/removed, false by default.
# File lib/sequel/model/associations.rb 430 def need_associated_primary_key? 431 false 432 end
A placeholder literalizer that can be used to lazily load the association. If one can't be used, returns nil.
# File lib/sequel/model/associations.rb 436 def placeholder_loader 437 if use_placeholder_loader? 438 cached_fetch(:placeholder_loader) do 439 Sequel::Dataset::PlaceholderLiteralizer.loader(associated_dataset) do |pl, ds| 440 ds = ds.where(Sequel.&(*predicate_keys.map{|k| SQL::BooleanExpression.new(:'=', k, pl.arg)})) 441 if self[:block] 442 ds = self[:block].call(ds) 443 end 444 ds 445 end 446 end 447 end 448 end
The values that predicate_keys
should match for objects to be associated.
# File lib/sequel/model/associations.rb 456 def predicate_key_values(object) 457 predicate_key_methods.map{|k| object.get_column_value(k)} 458 end
The keys to use for loading of the regular dataset, as an array.
# File lib/sequel/model/associations.rb 451 def predicate_keys 452 cached_fetch(:predicate_keys){Array(predicate_key)} 453 end
Qualify col
with the given table name.
# File lib/sequel/model/associations.rb 461 def qualify(table, col) 462 transform(col) do |k| 463 case k 464 when Symbol, SQL::Identifier 465 SQL::QualifiedIdentifier.new(table, k) 466 else 467 Sequel::Qualifier.new(table).transform(k) 468 end 469 end 470 end
Qualify col with the associated model's table name.
# File lib/sequel/model/associations.rb 473 def qualify_assoc(col) 474 qualify(associated_class.table_name, col) 475 end
Qualify col with the current model's table name.
# File lib/sequel/model/associations.rb 478 def qualify_cur(col) 479 qualify(self[:model].table_name, col) 480 end
Returns the reciprocal association variable, if one exists. The reciprocal association is the association in the associated class that is the opposite of the current association. For example, Album.many_to_one :artist and Artist.one_to_many :albums are reciprocal associations. This information is to populate reciprocal associations. For example, when you do this_artist.add_album(album) it sets album.artist to this_artist.
# File lib/sequel/model/associations.rb 488 def reciprocal 489 cached_fetch(:reciprocal) do 490 possible_recips = [] 491 492 associated_class.all_association_reflections.each do |assoc_reflect| 493 if reciprocal_association?(assoc_reflect) 494 possible_recips << assoc_reflect 495 end 496 end 497 498 if possible_recips.length == 1 499 cached_set(:reciprocal_type, possible_recips.first[:type]) if ambiguous_reciprocal_type? 500 possible_recips.first[:name] 501 end 502 end 503 end
Whether the reciprocal of this association returns an array of objects instead of a single object, true by default.
# File lib/sequel/model/associations.rb 507 def reciprocal_array? 508 true 509 end
Name symbol for the remove_all_ association method
# File lib/sequel/model/associations.rb 512 def remove_all_method 513 self[:remove_all_method] 514 end
Whether associated objects need to be removed from the association before being destroyed in order to preserve referential integrity.
# File lib/sequel/model/associations.rb 518 def remove_before_destroy? 519 true 520 end
Name symbol for the remove_ association method
# File lib/sequel/model/associations.rb 523 def remove_method 524 self[:remove_method] 525 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 528 def remove_should_check_existing? 529 false 530 end
Whether this association returns an array of objects instead of a single object, true by default.
# File lib/sequel/model/associations.rb 534 def returns_array? 535 true 536 end
The columns to select when loading the association.
# File lib/sequel/model/associations.rb 539 def select 540 self[:select] 541 end
Whether to set the reciprocal association to self when loading associated records, false by default.
# File lib/sequel/model/associations.rb 545 def set_reciprocal_to_self? 546 false 547 end
Name symbol for the setter association method
# File lib/sequel/model/associations.rb 550 def setter_method 551 self[:setter_method] 552 end
The range used for slicing when using the :ruby eager limit strategy.
# File lib/sequel/model/associations.rb 555 def slice_range(limit_and_offset = limit_and_offset()) 556 limit, offset = limit_and_offset 557 if limit || offset 558 (offset||0)..(limit ? (offset||0)+limit-1 : -1) 559 end 560 end
Private Instance Methods
The base dataset used for the association, before any order/conditions options have been applied.
# File lib/sequel/model/associations.rb 585 def _associated_dataset 586 associated_class.dataset 587 end
Whether for the reciprocal type for the given association cannot be known in advantage, false by default.
# File lib/sequel/model/associations.rb 591 def ambiguous_reciprocal_type? 592 false 593 end
Apply a distinct on eager limit strategy using IN with a subquery that uses DISTINCT ON to ensure only the first matching record for each key is included.
# File lib/sequel/model/associations.rb 611 def apply_filter_by_associations_distinct_on_limit_strategy(ds) 612 k = filter_by_associations_limit_key 613 ds.where(k=>apply_distinct_on_eager_limit_strategy(associated_eager_dataset.select(*k))) 614 end
Apply a limit strategy to the given dataset so that filter by associations works with a limited dataset.
# File lib/sequel/model/associations.rb 597 def apply_filter_by_associations_limit_strategy(ds) 598 case filter_by_associations_limit_strategy 599 when :distinct_on 600 apply_filter_by_associations_distinct_on_limit_strategy(ds) 601 when :window_function 602 apply_filter_by_associations_window_function_limit_strategy(ds) 603 else 604 ds 605 end 606 end
Apply a distinct on eager limit strategy using IN with a subquery that uses a filter on the row_number window function to ensure that only rows inside the limit are returned.
# File lib/sequel/model/associations.rb 619 def apply_filter_by_associations_window_function_limit_strategy(ds) 620 ds.where(filter_by_associations_limit_key=>apply_window_function_eager_limit_strategy(associated_eager_dataset.select(*filter_by_associations_limit_alias_key)).select(*filter_by_associations_limit_aliases)) 621 end
The associated_dataset
with the eager_block callback already applied.
# File lib/sequel/model/associations.rb 624 def associated_eager_dataset 625 cached_fetch(:associated_eager_dataset) do 626 ds = associated_dataset.unlimited 627 if block = self[:eager_block] 628 ds = block.call(ds) 629 end 630 ds 631 end 632 end
If the key exists in the reflection hash, return it. If the key doesn't exist and association reflections are uncached, then yield to get the value. If the key doesn't exist and association reflection are cached, check the cache and return the value if present, or yield to get the value, cache the value, and return it.
# File lib/sequel/model/associations.rb 568 def cached_fetch(key) 569 fetch(key) do 570 return yield unless h = self[:cache] 571 Sequel.synchronize{return h[key] if h.has_key?(key)} 572 value = yield 573 Sequel.synchronize{h[key] = value} 574 end 575 end
Cache the value at the given key if caching.
# File lib/sequel/model/associations.rb 578 def cached_set(key, value) 579 return unless h = self[:cache] 580 Sequel.synchronize{h[key] = value} 581 end
The default eager limit strategy to use for this association
# File lib/sequel/model/associations.rb 663 def default_eager_limit_strategy 664 self[:model].default_eager_limit_strategy || :ruby 665 end
The dataset to use for eager loading associated objects for multiple current objects, given the hash passed to the eager loader.
# File lib/sequel/model/associations.rb 636 def eager_loading_dataset(eo=OPTS) 637 ds = eo[:dataset] || associated_eager_dataset 638 if id_map = eo[:id_map] 639 ds = ds.where(eager_loading_predicate_condition(id_map.keys)) 640 end 641 if associations = eo[:associations] 642 ds = ds.eager(associations) 643 end 644 if block = eo[:eager_block] 645 orig_ds = ds 646 ds = block.call(ds) 647 end 648 if eager_loading_use_associated_key? 649 ds = if ds.opts[:eager_graph] && !orig_ds.opts[:eager_graph] 650 block.call(orig_ds.select_append(*associated_key_array)) 651 else 652 ds.select_append(*associated_key_array) 653 end 654 end 655 if self[:eager_graph] 656 raise(Error, "cannot eagerly load a #{self[:type]} association that uses :eager_graph") if eager_loading_use_associated_key? 657 ds = ds.eager_graph(self[:eager_graph]) 658 end 659 ds 660 end
The predicate condition to use for the eager_loader.
# File lib/sequel/model/associations.rb 668 def eager_loading_predicate_condition(keys) 669 {predicate_key=>keys} 670 end
Add conditions to the dataset to not include NULL values for the associated keys, and select those keys.
# File lib/sequel/model/associations.rb 674 def filter_by_associations_add_conditions_dataset_filter(ds) 675 k = filter_by_associations_conditions_associated_keys 676 ds.select(*k).where(Sequel.negate(k.zip([]))) 677 end
The base dataset to use for the filter by associations conditions subquery, regardless of the objects that are passed in as filter values.
# File lib/sequel/model/associations.rb 697 def filter_by_associations_conditions_dataset 698 cached_fetch(:filter_by_associations_conditions_dataset) do 699 ds = associated_eager_dataset.unordered 700 ds = filter_by_associations_add_conditions_dataset_filter(ds) 701 ds = apply_filter_by_associations_limit_strategy(ds) 702 ds 703 end 704 end
The conditions to add to the filter by associations conditions subquery to restrict it to to the object(s) that was used as the filter value.
# File lib/sequel/model/associations.rb 682 def filter_by_associations_conditions_subquery_conditions(obj) 683 key = qualify(associated_class.table_name, associated_class.primary_key) 684 case obj 685 when Array 686 {key=>obj.map(&:pk)} 687 when Sequel::Dataset 688 {key=>obj.select(*Array(qualify(associated_class.table_name, associated_class.primary_key)))} 689 else 690 Array(key).zip(Array(obj.pk)) 691 end 692 end
The strategy to use to filter by a limited association
# File lib/sequel/model/associations.rb 707 def filter_by_associations_limit_strategy 708 v = fetch(:filter_limit_strategy, self[:eager_limit_strategy]) 709 if v || self[:limit] || !returns_array? 710 case v ||= self[:model].default_eager_limit_strategy 711 when true, :union, :ruby 712 # Can't use a union or ruby-based strategy for filtering by associations, switch to default eager graph limit 713 # strategy. 714 true_eager_graph_limit_strategy 715 when Symbol 716 v 717 end 718 end 719 end
Whether to limit the associated dataset to a single row.
# File lib/sequel/model/associations.rb 722 def limit_to_single_row? 723 !returns_array? 724 end
Any offset to use for this association (or nil if there is no offset).
# File lib/sequel/model/associations.rb 727 def offset 728 limit_and_offset.last 729 end
A placeholder literalizer used to speed up eager loading.
# File lib/sequel/model/associations.rb 732 def placeholder_eager_loader 733 cached_fetch(:placeholder_eager_loader) do 734 Sequel::Dataset::PlaceholderLiteralizer.loader(associated_dataset) do |pl, ds| 735 apply_eager_limit_strategy(eager_loading_dataset.where(predicate_key=>pl.arg), eager_limit_strategy) 736 end 737 end 738 end
The reciprocal type as an array, should be overridden in reflection subclasses that have ambiguous reciprocal types.
# File lib/sequel/model/associations.rb 742 def possible_reciprocal_types 743 [reciprocal_type] 744 end
Whether the given association reflection is possible reciprocal association for the current association reflection.
# File lib/sequel/model/associations.rb 748 def reciprocal_association?(assoc_reflect) 749 possible_reciprocal_types.include?(assoc_reflect[:type]) && 750 (begin; assoc_reflect.associated_class; rescue NameError; end) == self[:model] && 751 assoc_reflect[:conditions].nil? && 752 assoc_reflect[:block].nil? 753 end
The number of subqueries to use in each union query, used to eagerly load limited associations. Defaults to 40, the optimal number depends on the latency between the database and the application.
# File lib/sequel/model/associations.rb 758 def subqueries_per_union 759 self[:subqueries_per_union] || 40 760 end
If s
is an array, map s
over the block. Otherwise, just call the block with s
.
# File lib/sequel/model/associations.rb 764 def transform(s, &block) 765 s.is_a?(Array) ? s.map(&block) : (yield s) 766 end
The eager_graph limit strategy used when true is given as the value, choosing the best strategy based on what the database supports.
# File lib/sequel/model/associations.rb 782 def true_eager_graph_limit_strategy 783 if associated_class.dataset.supports_window_functions? 784 :window_function 785 else 786 :ruby 787 end 788 end
What eager limit strategy should be used when true is given as the value, defaults to UNION as that is the fastest strategy if the appropriate keys are indexed.
# File lib/sequel/model/associations.rb 770 def true_eager_limit_strategy 771 if self[:eager_graph] || (offset && !associated_dataset.supports_offsets_in_correlated_subqueries?) 772 # An SQL-based approach won't work if you are also eager graphing, 773 # so use a ruby based approach in that case. 774 :ruby 775 else 776 :union 777 end 778 end
A placeholder literalizer used to speed up the creation of union queries when eager loading a limited association.
# File lib/sequel/model/associations.rb 792 def union_eager_loader 793 cached_fetch(:union_eager_loader) do 794 Sequel::Dataset::PlaceholderLiteralizer.loader(associated_dataset) do |pl, ds| 795 ds = self[:eager_block].call(ds) if self[:eager_block] 796 keys = predicate_keys 797 ds = ds.where(keys.map{pl.arg}.zip(keys)) 798 if eager_loading_use_associated_key? 799 ds = ds.select_append(*associated_key_array) 800 end 801 ds.from_self 802 end 803 end 804 end
Whether the placeholder loader can be used to load the association.
# File lib/sequel/model/associations.rb 807 def use_placeholder_loader? 808 self[:use_placeholder_loader] 809 end