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 if returns_array? 168 range = slice_range(limit_and_offset) 169 rows.each{|o| o.associations[name] = o.associations[name][range] || []} 170 elsif sr = slice_range(limit_and_offset) 171 offset = sr.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 finalize_settings.each 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 nil 368 end
# File lib/sequel/model/associations.rb 382 def finalize_settings 383 FINALIZE_SETTINGS 384 end
Whether to handle silent modification failure when adding/removing associated records, false by default.
# File lib/sequel/model/associations.rb 388 def handle_silent_modification_failure? 389 false 390 end
Initialize the associations cache for the current association for the given objects.
# File lib/sequel/model/associations.rb 393 def initialize_association_cache(objects) 394 name = self[:name] 395 if assign_singular? 396 objects.each{|object| object.associations[name] = nil} 397 else 398 objects.each{|object| object.associations[name] = []} 399 end 400 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 404 def inspect 405 o = self[:orig_opts].dup 406 o.delete(:class) 407 o.delete(:class_name) 408 o.delete(:block) unless o[:block] 409 o[:class] = self[:orig_class] if self[:orig_class] 410 411 "#<#{self.class} #{self[:model]}.#{self[:type]} #{self[:name].inspect}#{", #{o.inspect[1...-1]}" unless o.empty?}>" 412 end
The limit and offset for this association (returned as a two element array).
# File lib/sequel/model/associations.rb 415 def limit_and_offset 416 if (v = self[:limit]).is_a?(Array) 417 v 418 else 419 [v, nil] 420 end 421 end
Whether the associated object needs a primary key to be added/removed, false by default.
# File lib/sequel/model/associations.rb 425 def need_associated_primary_key? 426 false 427 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 431 def placeholder_loader 432 if use_placeholder_loader? 433 cached_fetch(:placeholder_loader) do 434 Sequel::Dataset::PlaceholderLiteralizer.loader(associated_dataset) do |pl, ds| 435 ds.where(Sequel.&(*predicate_keys.map{|k| SQL::BooleanExpression.new(:'=', k, pl.arg)})) 436 end 437 end 438 end 439 end
The values that predicate_keys
should match for objects to be associated.
# File lib/sequel/model/associations.rb 447 def predicate_key_values(object) 448 predicate_key_methods.map{|k| object.get_column_value(k)} 449 end
The keys to use for loading of the regular dataset, as an array.
# File lib/sequel/model/associations.rb 442 def predicate_keys 443 cached_fetch(:predicate_keys){Array(predicate_key)} 444 end
Qualify col
with the given table name.
# File lib/sequel/model/associations.rb 452 def qualify(table, col) 453 transform(col) do |k| 454 case k 455 when Symbol, SQL::Identifier 456 SQL::QualifiedIdentifier.new(table, k) 457 else 458 Sequel::Qualifier.new(table).transform(k) 459 end 460 end 461 end
Qualify col with the associated model's table name.
# File lib/sequel/model/associations.rb 464 def qualify_assoc(col) 465 qualify(associated_class.table_name, col) 466 end
Qualify col with the current model's table name.
# File lib/sequel/model/associations.rb 469 def qualify_cur(col) 470 qualify(self[:model].table_name, col) 471 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 479 def reciprocal 480 cached_fetch(:reciprocal) do 481 possible_recips = [] 482 483 associated_class.all_association_reflections.each do |assoc_reflect| 484 if reciprocal_association?(assoc_reflect) 485 possible_recips << assoc_reflect 486 end 487 end 488 489 if possible_recips.length == 1 490 cached_set(:reciprocal_type, possible_recips.first[:type]) if ambiguous_reciprocal_type? 491 possible_recips.first[:name] 492 end 493 end 494 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 498 def reciprocal_array? 499 true 500 end
Name symbol for the remove_all_ association method
# File lib/sequel/model/associations.rb 503 def remove_all_method 504 self[:remove_all_method] 505 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 509 def remove_before_destroy? 510 true 511 end
Name symbol for the remove_ association method
# File lib/sequel/model/associations.rb 514 def remove_method 515 self[:remove_method] 516 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 519 def remove_should_check_existing? 520 false 521 end
Whether this association returns an array of objects instead of a single object, true by default.
# File lib/sequel/model/associations.rb 525 def returns_array? 526 true 527 end
The columns to select when loading the association.
# File lib/sequel/model/associations.rb 530 def select 531 self[:select] 532 end
Whether to set the reciprocal association to self when loading associated records, false by default.
# File lib/sequel/model/associations.rb 536 def set_reciprocal_to_self? 537 false 538 end
Name symbol for the setter association method
# File lib/sequel/model/associations.rb 541 def setter_method 542 self[:setter_method] 543 end
The range used for slicing when using the :ruby eager limit strategy.
# File lib/sequel/model/associations.rb 546 def slice_range(limit_and_offset = limit_and_offset()) 547 limit, offset = limit_and_offset 548 if limit || offset 549 (offset||0)..(limit ? (offset||0)+limit-1 : -1) 550 end 551 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 576 def _associated_dataset 577 associated_class.dataset 578 end
Whether for the reciprocal type for the given association cannot be known in advantage, false by default.
# File lib/sequel/model/associations.rb 582 def ambiguous_reciprocal_type? 583 false 584 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 602 def apply_filter_by_associations_distinct_on_limit_strategy(ds) 603 k = filter_by_associations_limit_key 604 ds.where(k=>apply_distinct_on_eager_limit_strategy(associated_eager_dataset.select(*k))) 605 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 588 def apply_filter_by_associations_limit_strategy(ds) 589 case filter_by_associations_limit_strategy 590 when :distinct_on 591 apply_filter_by_associations_distinct_on_limit_strategy(ds) 592 when :window_function 593 apply_filter_by_associations_window_function_limit_strategy(ds) 594 else 595 ds 596 end 597 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 610 def apply_filter_by_associations_window_function_limit_strategy(ds) 611 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)) 612 end
The associated_dataset
with the eager_block callback already applied.
# File lib/sequel/model/associations.rb 615 def associated_eager_dataset 616 cached_fetch(:associated_eager_dataset) do 617 ds = associated_dataset.unlimited 618 if block = self[:eager_block] 619 ds = block.call(ds) 620 end 621 ds 622 end 623 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 559 def cached_fetch(key) 560 fetch(key) do 561 return yield unless h = self[:cache] 562 Sequel.synchronize{return h[key] if h.has_key?(key)} 563 value = yield 564 Sequel.synchronize{h[key] = value} 565 end 566 end
Cache the value at the given key if caching.
# File lib/sequel/model/associations.rb 569 def cached_set(key, value) 570 return unless h = self[:cache] 571 Sequel.synchronize{h[key] = value} 572 end
The default eager limit strategy to use for this association
# File lib/sequel/model/associations.rb 654 def default_eager_limit_strategy 655 self[:model].default_eager_limit_strategy || :ruby 656 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 627 def eager_loading_dataset(eo=OPTS) 628 ds = eo[:dataset] || associated_eager_dataset 629 if id_map = eo[:id_map] 630 ds = ds.where(eager_loading_predicate_condition(id_map.keys)) 631 end 632 if associations = eo[:associations] 633 ds = ds.eager(associations) 634 end 635 if block = eo[:eager_block] 636 orig_ds = ds 637 ds = block.call(ds) 638 end 639 if eager_loading_use_associated_key? 640 ds = if ds.opts[:eager_graph] && !orig_ds.opts[:eager_graph] 641 block.call(orig_ds.select_append(*associated_key_array)) 642 else 643 ds.select_append(*associated_key_array) 644 end 645 end 646 if self[:eager_graph] 647 raise(Error, "cannot eagerly load a #{self[:type]} association that uses :eager_graph") if eager_loading_use_associated_key? 648 ds = ds.eager_graph(self[:eager_graph]) 649 end 650 ds 651 end
The predicate condition to use for the eager_loader.
# File lib/sequel/model/associations.rb 659 def eager_loading_predicate_condition(keys) 660 {predicate_key=>keys} 661 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 665 def filter_by_associations_add_conditions_dataset_filter(ds) 666 k = filter_by_associations_conditions_associated_keys 667 ds.select(*k).where(Sequel.negate(k.zip([]))) 668 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 688 def filter_by_associations_conditions_dataset 689 cached_fetch(:filter_by_associations_conditions_dataset) do 690 ds = associated_eager_dataset.unordered 691 ds = filter_by_associations_add_conditions_dataset_filter(ds) 692 ds = apply_filter_by_associations_limit_strategy(ds) 693 ds 694 end 695 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 673 def filter_by_associations_conditions_subquery_conditions(obj) 674 key = qualify(associated_class.table_name, associated_class.primary_key) 675 case obj 676 when Array 677 {key=>obj.map(&:pk)} 678 when Sequel::Dataset 679 {key=>obj.select(*Array(qualify(associated_class.table_name, associated_class.primary_key)))} 680 else 681 Array(key).zip(Array(obj.pk)) 682 end 683 end
The strategy to use to filter by a limited association
# File lib/sequel/model/associations.rb 698 def filter_by_associations_limit_strategy 699 v = fetch(:filter_limit_strategy, self[:eager_limit_strategy]) 700 if v || self[:limit] || !returns_array? 701 case v ||= self[:model].default_eager_limit_strategy 702 when true, :union, :ruby 703 # Can't use a union or ruby-based strategy for filtering by associations, switch to default eager graph limit 704 # strategy. 705 true_eager_graph_limit_strategy 706 when Symbol 707 v 708 end 709 end 710 end
Whether to limit the associated dataset to a single row.
# File lib/sequel/model/associations.rb 713 def limit_to_single_row? 714 !returns_array? 715 end
Any offset to use for this association (or nil if there is no offset).
# File lib/sequel/model/associations.rb 718 def offset 719 limit_and_offset.last 720 end
A placeholder literalizer used to speed up eager loading.
# File lib/sequel/model/associations.rb 723 def placeholder_eager_loader 724 cached_fetch(:placeholder_eager_loader) do 725 Sequel::Dataset::PlaceholderLiteralizer.loader(associated_dataset) do |pl, ds| 726 apply_eager_limit_strategy(eager_loading_dataset.where(predicate_key=>pl.arg), eager_limit_strategy) 727 end 728 end 729 end
The reciprocal type as an array, should be overridden in reflection subclasses that have ambiguous reciprocal types.
# File lib/sequel/model/associations.rb 733 def possible_reciprocal_types 734 [reciprocal_type] 735 end
Whether the given association reflection is possible reciprocal association for the current association reflection.
# File lib/sequel/model/associations.rb 739 def reciprocal_association?(assoc_reflect) 740 possible_reciprocal_types.include?(assoc_reflect[:type]) && 741 (begin; assoc_reflect.associated_class; rescue NameError; end) == self[:model] && 742 assoc_reflect[:conditions].nil? && 743 assoc_reflect[:block].nil? 744 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 749 def subqueries_per_union 750 self[:subqueries_per_union] || 40 751 end
If s
is an array, map s
over the block. Otherwise, just call the block with s
.
# File lib/sequel/model/associations.rb 755 def transform(s, &block) 756 s.is_a?(Array) ? s.map(&block) : (yield s) 757 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 773 def true_eager_graph_limit_strategy 774 if associated_class.dataset.supports_window_functions? 775 :window_function 776 else 777 :ruby 778 end 779 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 761 def true_eager_limit_strategy 762 if self[:eager_graph] || (offset && !associated_dataset.supports_offsets_in_correlated_subqueries?) 763 # An SQL-based approach won't work if you are also eager graphing, 764 # so use a ruby based approach in that case. 765 :ruby 766 else 767 :union 768 end 769 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 783 def union_eager_loader 784 cached_fetch(:union_eager_loader) do 785 Sequel::Dataset::PlaceholderLiteralizer.loader(associated_dataset) do |pl, ds| 786 ds = self[:eager_block].call(ds) if self[:eager_block] 787 keys = predicate_keys 788 ds = ds.where(keys.map{pl.arg}.zip(keys)) 789 if eager_loading_use_associated_key? 790 ds = ds.select_append(*associated_key_array) 791 end 792 ds.from_self 793 end 794 end 795 end
Whether the placeholder loader can be used to load the association.
# File lib/sequel/model/associations.rb 798 def use_placeholder_loader? 799 !self[:instance_specific] && !self[:eager_graph] 800 end