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
Public Instance Methods
Name symbol for the _add internal association method
# File lib/sequel/model/associations.rb, line 25 def _add_method :"_add_#{singularize(self[:name])}" end
Name symbol for the _remove_all internal association method
# File lib/sequel/model/associations.rb, line 30 def _remove_all_method :"_remove_all_#{self[:name]}" end
Name symbol for the _remove internal association method
# File lib/sequel/model/associations.rb, line 35 def _remove_method :"_remove_#{singularize(self[:name])}" end
Name symbol for the _setter association method
# File lib/sequel/model/associations.rb, line 40 def _setter_method :"_#{self[:name]}=" end
Name symbol for the add association method
# File lib/sequel/model/associations.rb, line 45 def add_method :"add_#{singularize(self[:name])}" end
Apply all non-instance specific changes to the given dataset and return it.
# File lib/sequel/model/associations.rb, line 67 def apply_dataset_changes(ds) ds.extend(AssociationDatasetMethods) ds.association_reflection = self self[:extend].each{|m| ds.extend(m)} ds = ds.select(*select) if select if c = self[:conditions] ds = (c.is_a?(Array) && !Sequel.condition_specifier?(c)) ? ds.where(*c) : ds.where(c) end ds = ds.order(*self[:order]) if self[:order] ds = ds.limit(*self[:limit]) if self[:limit] ds = ds.limit(1) if limit_to_single_row? ds = ds.eager(self[:eager]) if self[:eager] ds = ds.distinct if self[:distinct] ds 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, line 120 def apply_distinct_on_eager_limit_strategy(ds) keys = predicate_key ds.distinct(*keys).order_prepend(*keys) 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, line 85 def apply_eager_dataset_changes(ds) ds = apply_dataset_changes(ds) if block = self[:eager_block] ds = block.call(ds) end ds 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, line 95 def apply_eager_graph_limit_strategy(strategy, ds) case strategy when :distinct_on apply_distinct_on_eager_limit_strategy(ds.order_prepend(*self[:order])) when :window_function apply_window_function_eager_limit_strategy(ds.order_prepend(*self[:order])).select(*ds.columns) else ds end 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, line 108 def apply_eager_limit_strategy(ds, strategy=eager_limit_strategy) case strategy when :distinct_on apply_distinct_on_eager_limit_strategy(ds) when :window_function apply_window_function_eager_limit_strategy(ds) else ds end 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, line 146 def apply_ruby_eager_limit_strategy(rows) name = self[:name] if returns_array? range = slice_range rows.each{|o| o.associations[name] = o.associations[name][range] || []} elsif slice_range offset = slice_range.begin rows.each{|o| o.associations[name] = o.associations[name][offset]} end end
Use a window function to limit the results of the eager loading dataset.
# File lib/sequel/model/associations.rb, line 126 def apply_window_function_eager_limit_strategy(ds) rn = ds.row_number_column limit, offset = limit_and_offset ds = ds.unordered.select_append{|o| o.row_number{}.over(:partition=>predicate_key, :order=>ds.opts[:order]).as(rn)}.from_self ds = if !returns_array? ds.where(rn => offset ? offset+1 : 1) elsif offset offset += 1 if limit ds.where(rn => (offset...(offset+limit))) else ds.where{SQL::Identifier.new(rn) >= offset} end else ds.where{SQL::Identifier.new(rn) <= limit} end end
Whether the associations cache should use an array when storing the associated records during eager loading.
# File lib/sequel/model/associations.rb, line 159 def assign_singular? !returns_array? end
The class associated to the current model class via this association
# File lib/sequel/model/associations.rb, line 55 def associated_class cached_fetch(:class){constantize(self[:class_name])} 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, line 62 def associated_dataset cached_fetch(:_dataset){apply_dataset_changes(_associated_dataset)} end
Return an dataset that will load the appropriate associated objects for the given object using this association.
# File lib/sequel/model/associations.rb, line 196 def association_dataset_for(object) associated_dataset.where(predicate_keys.zip(predicate_key_values(object))) end
Proc used to create the association dataset method.
# File lib/sequel/model/associations.rb, line 202 def association_dataset_proc ASSOCIATION_DATASET_PROC end
Name symbol for association method, the same as the name of the association.
# File lib/sequel/model/associations.rb, line 50 def association_method self[:name] 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, line 166 def can_have_associated_objects?(obj) true 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, line 172 def cloneable?(ref) ref[:type] == self[:type] end
Name symbol for the dataset association method
# File lib/sequel/model/associations.rb, line 177 def dataset_method :"#{self[:name]}_dataset" end
Whether the dataset needs a primary key to function, true by default.
# File lib/sequel/model/associations.rb, line 182 def dataset_need_primary_key? true 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, line 188 def delete_row_number_column(ds=associated_dataset) if eager_limit_strategy == :window_function ds.row_number_column end 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, line 295 def eager_graph_lazy_dataset? true end
The eager_graph limit strategy to use for this dataset
# File lib/sequel/model/associations.rb, line 207 def eager_graph_limit_strategy(strategy) if self[:limit] || !returns_array? strategy = strategy[self[:name]] if strategy.is_a?(Hash) case strategy when true true_eager_graph_limit_strategy when Symbol strategy else if returns_array? || offset :ruby end end end end
The eager limit strategy to use for this dataset.
# File lib/sequel/model/associations.rb, line 224 def eager_limit_strategy cached_fetch(:_eager_limit_strategy) do if self[:limit] || !returns_array? case s = cached_fetch(:eager_limit_strategy){default_eager_limit_strategy} when true true_eager_limit_strategy else s end end end end
Eager load the associated objects using the hash of eager options, yielding each row to the block.
# File lib/sequel/model/associations.rb, line 239 def eager_load_results(eo, &block) rows = eo[:rows] initialize_association_cache(rows) unless eo[:initialize_rows] == false if eo[:id_map] ids = eo[:id_map].keys return ids if ids.empty? end strategy = eager_limit_strategy cascade = eo[:associations] if eo[:eager_block] || eo[:loader] == false strategy = true_eager_graph_limit_strategy if strategy == :union # Correlated subqueries are not supported for regular eager loading strategy = :ruby if strategy == :correlated_subquery objects = apply_eager_limit_strategy(eager_loading_dataset(eo), strategy).all elsif strategy == :union objects = [] ds = associated_dataset loader = union_eager_loader joiner = " UNION ALL " ids.each_slice(subqueries_per_union).each do |slice| objects.concat(ds.with_sql(slice.map{|k| loader.sql(*k)}.join(joiner)).to_a) end ds = ds.eager(cascade) if cascade ds.send(:post_load, objects) else loader = placeholder_eager_loader loader = loader.with_dataset{|dataset| dataset.eager(cascade)} if cascade objects = loader.all(ids) end objects.each(&block) if strategy == :ruby apply_ruby_eager_limit_strategy(rows) end end
The key to use for the key hash when eager loading
# File lib/sequel/model/associations.rb, line 277 def eager_loader_key self[:eager_loader_key] end
Alias of predicate_key, only for backwards compatibility.
# File lib/sequel/model/associations.rb, line 288 def eager_loading_predicate_key predicate_key end
By default associations do not need to select a key in an associated table to eagerly load.
# File lib/sequel/model/associations.rb, line 283 def eager_loading_use_associated_key? false end
Whether additional conditions should be added when using the filter by associations support.
# File lib/sequel/model/associations.rb, line 301 def filter_by_associations_add_conditions? self[:conditions] || self[:eager_block] || self[:limit] 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, line 309 def filter_by_associations_conditions_expression(obj) ds = filter_by_associations_conditions_dataset.where(filter_by_associations_conditions_subquery_conditions(obj)) {filter_by_associations_conditions_key=>ds} end
Whether to handle silent modification failure when adding/removing associated records, false by default.
# File lib/sequel/model/associations.rb, line 316 def handle_silent_modification_failure? false end
Initialize the associations cache for the current association for the given objects.
# File lib/sequel/model/associations.rb, line 321 def initialize_association_cache(objects) name = self[:name] if assign_singular? objects.each{|object| object.associations[name] = nil} else objects.each{|object| object.associations[name] = []} end end
The limit and offset for this association (returned as a two element array).
# File lib/sequel/model/associations.rb, line 331 def limit_and_offset if (v = self[:limit]).is_a?(Array) v else [v, nil] end end
Whether the associated object needs a primary key to be added/removed, false by default.
# File lib/sequel/model/associations.rb, line 341 def need_associated_primary_key? false 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, line 347 def placeholder_loader if use_placeholder_loader? cached_fetch(:placeholder_loader) do Sequel::Dataset::PlaceholderLiteralizer.loader(associated_dataset) do |pl, ds| ds.where(*predicate_keys.map{|k| SQL::BooleanExpression.new(:'=', k, pl.arg)}) end end end end
The values that #predicate_keys should match for objects to be associated.
# File lib/sequel/model/associations.rb, line 363 def predicate_key_values(object) predicate_key_methods.map{|k| object.get_column_value(k)} end
The keys to use for loading of the regular dataset, as an array.
# File lib/sequel/model/associations.rb, line 358 def predicate_keys cached_fetch(:predicate_keys){Array(predicate_key)} end
Qualify col
with the given table name. If col
is
an array of columns, return an array of qualified columns. Only qualifies
Symbols and SQL::Identifier values,
other values are not modified.
# File lib/sequel/model/associations.rb, line 370 def qualify(table, col) transform(col) do |k| case k when Symbol, SQL::Identifier SQL::QualifiedIdentifier.new(table, k) else Sequel::Qualifier.new(self[:model].dataset, table).transform(k) end end end
Qualify col with the associated model's table name.
# File lib/sequel/model/associations.rb, line 382 def qualify_assoc(col) qualify(associated_class.table_name, col) end
Qualify col with the current model's table name.
# File lib/sequel/model/associations.rb, line 387 def qualify_cur(col) qualify(self[:model].table_name, col) 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, line 397 def reciprocal cached_fetch(:reciprocal) do possible_recips = [] associated_class.all_association_reflections.each do |assoc_reflect| if reciprocal_association?(assoc_reflect) possible_recips << assoc_reflect end end if possible_recips.length == 1 cached_set(:reciprocal_type, possible_recips.first[:type]) if ambiguous_reciprocal_type? possible_recips.first[:name] end end 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, line 416 def reciprocal_array? true end
Name symbol for the remove_all_ association method
# File lib/sequel/model/associations.rb, line 421 def remove_all_method :"remove_all_#{self[:name]}" 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, line 427 def remove_before_destroy? true end
Name symbol for the remove_ association method
# File lib/sequel/model/associations.rb, line 432 def remove_method :"remove_#{singularize(self[:name])}" 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, line 437 def remove_should_check_existing? false end
Whether this association returns an array of objects instead of a single object, true by default.
# File lib/sequel/model/associations.rb, line 443 def returns_array? true end
The columns to select when loading the association.
# File lib/sequel/model/associations.rb, line 448 def select self[:select] end
Whether to set the reciprocal association to self when loading associated records, false by default.
# File lib/sequel/model/associations.rb, line 454 def set_reciprocal_to_self? false end
Name symbol for the setter association method
# File lib/sequel/model/associations.rb, line 459 def setter_method :"#{self[:name]}=" end
The range used for slicing when using the :ruby eager limit strategy.
# File lib/sequel/model/associations.rb, line 464 def slice_range limit, offset = limit_and_offset if limit || offset (offset||0)..(limit ? (offset||0)+limit-1 : -1) end 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, line 511 def _associated_dataset associated_class.dataset.clone end
Whether for the reciprocal type for the given association can not be known in advantage, false by default.
# File lib/sequel/model/associations.rb, line 517 def ambiguous_reciprocal_type? false 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, line 537 def apply_filter_by_associations_distinct_on_limit_strategy(ds) k = filter_by_associations_limit_key ds.where(k=>apply_distinct_on_eager_limit_strategy(associated_eager_dataset.select(*k))) 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, line 523 def apply_filter_by_associations_limit_strategy(ds) case filter_by_associations_limit_strategy when :distinct_on apply_filter_by_associations_distinct_on_limit_strategy(ds) when :window_function apply_filter_by_associations_window_function_limit_strategy(ds) else ds end 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, line 545 def apply_filter_by_associations_window_function_limit_strategy(ds) 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)) end
The #associated_dataset with the eager_block callback already applied.
# File lib/sequel/model/associations.rb, line 550 def associated_eager_dataset cached_fetch(:associated_eager_dataset) do ds = associated_dataset.unlimited if block = self[:eager_block] ds = block.call(ds) end ds end end
:nocov: On non-GVL rubies, assume the need to synchronize access. Store the key in a special sub-hash that always uses this method to synchronize access.
# File lib/sequel/model/associations.rb, line 477 def cached_fetch(key) fetch(key) do return yield unless h = self[:cache] Sequel.synchronize{return h[key] if h.has_key?(key)} value = yield Sequel.synchronize{h[key] = value} end end
Cache the value at the given key, synchronizing access.
# File lib/sequel/model/associations.rb, line 487 def cached_set(key, value) return unless h = self[:cache] Sequel.synchronize{h[key] = value} end
The default eager limit strategy to use for this association
# File lib/sequel/model/associations.rb, line 584 def default_eager_limit_strategy self[:model].default_eager_limit_strategy || :ruby 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, line 562 def eager_loading_dataset(eo=OPTS) ds = eo[:dataset] || associated_eager_dataset if id_map = eo[:id_map] ds = ds.where(eager_loading_predicate_condition(id_map.keys)) end if associations = eo[:associations] ds = ds.eager(associations) end if block = eo[:eager_block] ds = block.call(ds) end if eager_loading_use_associated_key? ds = ds.select_append(*associated_key_array) end if self[:eager_graph] raise(Error, "cannot eagerly load a #{self[:type]} association that uses :eager_graph") if eager_loading_use_associated_key? ds = ds.eager_graph(self[:eager_graph]) end ds end
The predicate condition to use for the eager_loader.
# File lib/sequel/model/associations.rb, line 589 def eager_loading_predicate_condition(keys) {predicate_key=>keys} 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, line 595 def filter_by_associations_add_conditions_dataset_filter(ds) k = filter_by_associations_conditions_associated_keys ds.select(*k).where(Sequel.negate(k.zip([]))) 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, line 618 def filter_by_associations_conditions_dataset cached_fetch(:filter_by_associations_conditions_dataset) do ds = associated_eager_dataset.unordered ds = filter_by_associations_add_conditions_dataset_filter(ds) ds = apply_filter_by_associations_limit_strategy(ds) ds end 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, line 603 def filter_by_associations_conditions_subquery_conditions(obj) key = qualify(associated_class.table_name, associated_class.primary_key) case obj when Array {key=>obj.map{|o| o.pk}} when Sequel::Dataset {key=>obj.select(*Array(qualify(associated_class.table_name, associated_class.primary_key)))} else Array(key).zip(Array(obj.pk)) end end
The strategy to use to filter by a limited association
# File lib/sequel/model/associations.rb, line 628 def filter_by_associations_limit_strategy v = fetch(:filter_limit_strategy, self[:eager_limit_strategy]) if v || self[:limit] || !returns_array? case v ||= self[:model].default_eager_limit_strategy when :union, :ruby # Can't use a union or ruby-based strategy for filtering by associations, switch to default eager graph limit # strategy. true_eager_graph_limit_strategy when Symbol v when true true_eager_graph_limit_strategy end end end
Whether to limit the associated dataset to a single row.
# File lib/sequel/model/associations.rb, line 645 def limit_to_single_row? !returns_array? end
Any offset to use for this association (or nil if there is no offset).
# File lib/sequel/model/associations.rb, line 650 def offset limit_and_offset.last end
A placeholder literalizer used to speed up eager loading.
# File lib/sequel/model/associations.rb, line 655 def placeholder_eager_loader cached_fetch(:placeholder_eager_loader) do Sequel::Dataset::PlaceholderLiteralizer.loader(associated_dataset) do |pl, ds| apply_eager_limit_strategy(eager_loading_dataset.where(predicate_key=>pl.arg), eager_limit_strategy) end end end
The reciprocal type as an array, should be overridden in reflection subclasses that have ambiguous reciprocal types.
# File lib/sequel/model/associations.rb, line 665 def possible_reciprocal_types [reciprocal_type] end
Whether the given association reflection is possible reciprocal association for the current association reflection.
# File lib/sequel/model/associations.rb, line 671 def reciprocal_association?(assoc_reflect) possible_reciprocal_types.include?(assoc_reflect[:type]) && (begin; assoc_reflect.associated_class; rescue NameError; end) == self[:model] && assoc_reflect[:conditions].nil? && assoc_reflect[:block].nil? 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, line 681 def subqueries_per_union self[:subqueries_per_union] || 40 end
If s
is an array, map s
over the block.
Otherwise, just call the block with s
.
# File lib/sequel/model/associations.rb, line 687 def transform(s) s.is_a?(Array) ? s.map(&Proc.new) : (yield s) 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, line 705 def true_eager_graph_limit_strategy if associated_class.dataset.supports_window_functions? :window_function else :ruby end 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, line 693 def true_eager_limit_strategy if self[:eager_graph] || (offset && !associated_dataset.supports_offsets_in_correlated_subqueries?) # An SQL-based approach won't work if you are also eager graphing, # so use a ruby based approach in that case. :ruby else :union end 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, line 715 def union_eager_loader cached_fetch(:union_eager_loader) do Sequel::Dataset::PlaceholderLiteralizer.loader(associated_dataset) do |pl, ds| ds = self[:eager_block].call(ds) if self[:eager_block] keys = predicate_keys ds = ds.where(keys.map{pl.arg}.zip(keys)) if eager_loading_use_associated_key? ds = ds.select_append(*associated_key_array) end ds.from_self end end end
Whether the placeholder loader can be used to load the association.
# File lib/sequel/model/associations.rb, line 730 def use_placeholder_loader? !self[:instance_specific] && !self[:eager_graph] end