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, line 34 def _add_method :"_add_#{singularize(self[:name])}" end
Name symbol for the _remove_all internal association method
# File lib/sequel/model/associations.rb, line 39 def _remove_all_method :"_remove_all_#{self[:name]}" end
Name symbol for the _remove internal association method
# File lib/sequel/model/associations.rb, line 44 def _remove_method :"_remove_#{singularize(self[:name])}" end
Name symbol for the _setter association method
# File lib/sequel/model/associations.rb, line 49 def _setter_method :"_#{self[:name]}=" end
Name symbol for the add association method
# File lib/sequel/model/associations.rb, line 54 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 82 def apply_dataset_changes(ds) ds = ds.with_extend(AssociationDatasetMethods). clone(:association_reflection => self) self[:extend].each{|m| ds = ds.with_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).skip_limit_check 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 135 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 100 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 110 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 123 def apply_eager_limit_strategy(ds, strategy=eager_limit_strategy, limit_and_offset=limit_and_offset()) case strategy when :distinct_on apply_distinct_on_eager_limit_strategy(ds) when :window_function apply_window_function_eager_limit_strategy(ds, limit_and_offset) 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 161 def apply_ruby_eager_limit_strategy(rows, limit_and_offset = limit_and_offset()) name = self[:name] if returns_array? range = slice_range(limit_and_offset) rows.each{|o| o.associations[name] = o.associations[name][range] || []} elsif sr = slice_range(limit_and_offset) offset = sr.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 141 def apply_window_function_eager_limit_strategy(ds, limit_and_offset=limit_and_offset()) 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 174 def assign_singular? !returns_array? end
The class associated to the current model class via this association
# File lib/sequel/model/associations.rb, line 64 def associated_class cached_fetch(:class) do begin constantize(self[:class_name]) rescue NameError => e raise NameError, "#{e.message} (this happened when attempting to find the associated class for #{inspect})", e.backtrace end end 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 77 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 211 def association_dataset_for(object) condition = if can_have_associated_objects?(object) predicate_keys.zip(predicate_key_values(object)) else false end associated_dataset.where(condition) end
Proc used to create the association dataset method.
# File lib/sequel/model/associations.rb, line 223 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 59 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 181 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 187 def cloneable?(ref) ref[:type] == self[:type] end
Name symbol for the dataset association method
# File lib/sequel/model/associations.rb, line 192 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 197 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 203 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 335 def eager_graph_lazy_dataset? true end
The eager_graph limit strategy to use for this dataset
# File lib/sequel/model/associations.rb, line 228 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 245 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 260 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] eager_limit = nil if eo[:eager_block] || eo[:loader] == false ds = eager_loading_dataset(eo) strategy = ds.opts[:eager_limit_strategy] || strategy eager_limit = if el = ds.opts[:eager_limit] raise Error, "The :eager_limit dataset option is not supported for associations returning a single record" unless returns_array? strategy ||= true_eager_graph_limit_strategy if el.is_a?(Array) el else [el, nil] end else limit_and_offset end strategy = true_eager_graph_limit_strategy if strategy == :union # Correlated subqueries are not supported for regular eager loading strategy = :ruby if strategy == :correlated_subquery strategy = nil if strategy == :ruby && assign_singular? objects = apply_eager_limit_strategy(ds, strategy, eager_limit).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, eager_limit || limit_and_offset) end end
The key to use for the key hash when eager loading
# File lib/sequel/model/associations.rb, line 317 def eager_loader_key self[:eager_loader_key] end
Alias of predicate_key, only for backwards compatibility.
# File lib/sequel/model/associations.rb, line 328 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 323 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 341 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 349 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
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, line 357 def finalize return unless cache = self[:cache] finalize_settings.each do |meth, key| next if has_key?(key) send(meth) self[key] = cache.delete(key) if cache.has_key?(key) end nil end
# File lib/sequel/model/associations.rb, line 382 def finalize_settings FINALIZE_SETTINGS end
Whether to handle silent modification failure when adding/removing associated records, false by default.
# File lib/sequel/model/associations.rb, line 388 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 393 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
Show which type of reflection this is, and a guess at what line was used to create the association.
# File lib/sequel/model/associations.rb, line 404 def inspect o = self[:orig_opts].dup o.delete(:class) o.delete(:class_name) o.delete(:block) unless o[:block] o[:class] = self[:orig_class] if self[:orig_class] "#<#{self.class} #{self[:model]}.#{self[:type]} #{self[:name].inspect}#{", #{o.inspect[1...-1]}" unless o.empty?}>" end
The limit and offset for this association (returned as a two element array).
# File lib/sequel/model/associations.rb, line 415 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 425 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 431 def placeholder_loader if use_placeholder_loader? cached_fetch(:placeholder_loader) do Sequel::Dataset::PlaceholderLiteralizer.loader(associated_dataset) do |pl, ds| ds.where(Sequel.&(*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 447 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 442 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 454 def qualify(table, col) transform(col) do |k| case k when Symbol, SQL::Identifier SQL::QualifiedIdentifier.new(table, k) else Sequel::Qualifier.new(table).transform(k) end end end
Qualify col with the associated model's table name.
# File lib/sequel/model/associations.rb, line 466 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 471 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 481 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 500 def reciprocal_array? true end
Name symbol for the remove_all_ association method
# File lib/sequel/model/associations.rb, line 505 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 511 def remove_before_destroy? true end
Name symbol for the remove_ association method
# File lib/sequel/model/associations.rb, line 516 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 521 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 527 def returns_array? true end
The columns to select when loading the association.
# File lib/sequel/model/associations.rb, line 532 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 538 def set_reciprocal_to_self? false end
Name symbol for the setter association method
# File lib/sequel/model/associations.rb, line 543 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 548 def slice_range(limit_and_offset = limit_and_offset()) 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 576 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 582 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 602 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 588 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 610 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 615 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
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 559 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 569 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 649 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 627 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 654 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 660 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 683 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 668 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(&: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 693 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 710 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 715 def offset limit_and_offset.last end
A placeholder literalizer used to speed up eager loading.
# File lib/sequel/model/associations.rb, line 720 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 730 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 736 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 746 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 752 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 770 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 758 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 780 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 795 def use_placeholder_loader? !self[:instance_specific] && !self[:eager_graph] end