Class | Sequel::Model::Associations::AssociationReflection |
In: |
lib/sequel/model/associations.rb
|
Parent: | Hash |
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.
ASSOCIATION_DATASET_PROC | = | proc{|r| r.association_dataset_for(self)} |
Name symbol for the _add internal association method
# File lib/sequel/model/associations.rb, line 25 25: def _add_method 26: 27: "_add_#{singularize(self[:name])}" 28: end
Name symbol for the _remove_all internal association method
# File lib/sequel/model/associations.rb, line 30 30: def _remove_all_method 31: 32: "_remove_all_#{self[:name]}" 33: end
Name symbol for the _remove internal association method
# File lib/sequel/model/associations.rb, line 35 35: def _remove_method 36: 37: "_remove_#{singularize(self[:name])}" 38: end
Name symbol for the _setter association method
# File lib/sequel/model/associations.rb, line 40 40: def _setter_method 41: 42: "_#{self[:name]}=" 43: end
Name symbol for the add association method
# File lib/sequel/model/associations.rb, line 45 45: def add_method 46: 47: "add_#{singularize(self[:name])}" 48: end
Apply all non-instance specific changes to the given dataset and return it.
# File lib/sequel/model/associations.rb, line 67 67: def apply_dataset_changes(ds) 68: ds.extend(AssociationDatasetMethods) 69: ds.association_reflection = self 70: self[:extend].each{|m| ds.extend(m)} 71: ds = ds.select(*select) if select 72: if c = self[:conditions] 73: ds = (c.is_a?(Array) && !Sequel.condition_specifier?(c)) ? ds.where(*c) : ds.where(c) 74: end 75: ds = ds.order(*self[:order]) if self[:order] 76: ds = ds.limit(*self[:limit]) if self[:limit] 77: ds = ds.limit(1) if limit_to_single_row? 78: ds = ds.eager(self[:eager]) if self[:eager] 79: ds = ds.distinct if self[:distinct] 80: ds 81: 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 120 120: def apply_distinct_on_eager_limit_strategy(ds) 121: keys = predicate_key 122: ds.distinct(*keys).order_prepend(*keys) 123: 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 85: def apply_eager_dataset_changes(ds) 86: ds = apply_dataset_changes(ds) 87: if block = self[:eager_block] 88: ds = block.call(ds) 89: end 90: ds 91: 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 95: def apply_eager_graph_limit_strategy(strategy, ds) 96: case strategy 97: when :distinct_on 98: apply_distinct_on_eager_limit_strategy(ds.order_prepend(*self[:order])) 99: when :window_function 100: apply_window_function_eager_limit_strategy(ds.order_prepend(*self[:order])).select(*ds.columns) 101: else 102: ds 103: end 104: 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 108 108: def apply_eager_limit_strategy(ds, strategy=eager_limit_strategy) 109: case strategy 110: when :distinct_on 111: apply_distinct_on_eager_limit_strategy(ds) 112: when :window_function 113: apply_window_function_eager_limit_strategy(ds) 114: else 115: ds 116: end 117: 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 146 146: def apply_ruby_eager_limit_strategy(rows) 147: name = self[:name] 148: if returns_array? 149: range = slice_range 150: rows.each{|o| o.associations[name] = o.associations[name][range] || []} 151: elsif slice_range 152: offset = slice_range.begin 153: rows.each{|o| o.associations[name] = o.associations[name][offset]} 154: end 155: end
Use a window function to limit the results of the eager loading dataset.
# File lib/sequel/model/associations.rb, line 126 126: def apply_window_function_eager_limit_strategy(ds) 127: rn = ds.row_number_column 128: limit, offset = limit_and_offset 129: ds = ds.unordered.select_append{|o| o.row_number{}.over(:partition=>predicate_key, :order=>ds.opts[:order]).as(rn)}.from_self 130: ds = if !returns_array? 131: ds.where(rn => offset ? offset+1 : 1) 132: elsif offset 133: offset += 1 134: if limit 135: ds.where(rn => (offset...(offset+limit))) 136: else 137: ds.where{SQL::Identifier.new(rn) >= offset} 138: end 139: else 140: ds.where{SQL::Identifier.new(rn) <= limit} 141: end 142: end
Whether the associations cache should use an array when storing the associated records during eager loading.
# File lib/sequel/model/associations.rb, line 159 159: def assign_singular? 160: !returns_array? 161: end
The class associated to the current model class via this association
# File lib/sequel/model/associations.rb, line 55 55: def associated_class 56: cached_fetch(:class){constantize(self[:class_name])} 57: 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 62: def associated_dataset 63: cached_fetch(:_dataset){apply_dataset_changes(_associated_dataset)} 64: 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 196 196: def association_dataset_for(object) 197: associated_dataset.where(predicate_keys.zip(predicate_key_values(object))) 198: end
Proc used to create the association dataset method.
# File lib/sequel/model/associations.rb, line 202 202: def association_dataset_proc 203: ASSOCIATION_DATASET_PROC 204: end
Name symbol for association method, the same as the name of the association.
# File lib/sequel/model/associations.rb, line 50 50: def association_method 51: self[:name] 52: 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 166 166: def can_have_associated_objects?(obj) 167: true 168: 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 172 172: def cloneable?(ref) 173: ref[:type] == self[:type] 174: end
Name symbol for the dataset association method
# File lib/sequel/model/associations.rb, line 177 177: def dataset_method 178: 179: "#{self[:name]}_dataset" 180: end
Whether the dataset needs a primary key to function, true by default.
# File lib/sequel/model/associations.rb, line 182 182: def dataset_need_primary_key? 183: true 184: 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 188 188: def delete_row_number_column(ds=associated_dataset) 189: if eager_limit_strategy == :window_function 190: ds.row_number_column 191: end 192: 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 295 295: def eager_graph_lazy_dataset? 296: true 297: end
The eager_graph limit strategy to use for this dataset
# File lib/sequel/model/associations.rb, line 207 207: def eager_graph_limit_strategy(strategy) 208: if self[:limit] || !returns_array? 209: strategy = strategy[self[:name]] if strategy.is_a?(Hash) 210: case strategy 211: when true 212: true_eager_graph_limit_strategy 213: when Symbol 214: strategy 215: else 216: if returns_array? || offset 217: :ruby 218: end 219: end 220: end 221: end
The eager limit strategy to use for this dataset.
# File lib/sequel/model/associations.rb, line 224 224: def eager_limit_strategy 225: cached_fetch(:_eager_limit_strategy) do 226: if self[:limit] || !returns_array? 227: case s = cached_fetch(:eager_limit_strategy){default_eager_limit_strategy} 228: when true 229: true_eager_limit_strategy 230: else 231: s 232: end 233: end 234: end 235: 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 239 239: def eager_load_results(eo, &block) 240: rows = eo[:rows] 241: initialize_association_cache(rows) unless eo[:initialize_rows] == false 242: if eo[:id_map] 243: ids = eo[:id_map].keys 244: return ids if ids.empty? 245: end 246: strategy = eager_limit_strategy 247: cascade = eo[:associations] 248: 249: if eo[:eager_block] || eo[:loader] == false 250: strategy = true_eager_graph_limit_strategy if strategy == :union 251: # Correlated subqueries are not supported for regular eager loading 252: strategy = :ruby if strategy == :correlated_subquery 253: objects = apply_eager_limit_strategy(eager_loading_dataset(eo), strategy).all 254: elsif strategy == :union 255: objects = [] 256: ds = associated_dataset 257: loader = union_eager_loader 258: joiner = " UNION ALL " 259: ids.each_slice(subqueries_per_union).each do |slice| 260: objects.concat(ds.with_sql(slice.map{|k| loader.sql(*k)}.join(joiner)).to_a) 261: end 262: ds = ds.eager(cascade) if cascade 263: ds.send(:post_load, objects) 264: else 265: loader = placeholder_eager_loader 266: loader = loader.with_dataset{|dataset| dataset.eager(cascade)} if cascade 267: objects = loader.all(ids) 268: end 269: 270: objects.each(&block) 271: if strategy == :ruby 272: apply_ruby_eager_limit_strategy(rows) 273: end 274: end
The key to use for the key hash when eager loading
# File lib/sequel/model/associations.rb, line 277 277: def eager_loader_key 278: self[:eager_loader_key] 279: end
Alias of predicate_key, only for backwards compatibility.
# File lib/sequel/model/associations.rb, line 288 288: def eager_loading_predicate_key 289: predicate_key 290: end
Whether additional conditions should be added when using the filter by associations support.
# File lib/sequel/model/associations.rb, line 301 301: def filter_by_associations_add_conditions? 302: self[:conditions] || self[:eager_block] || self[:limit] 303: 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 309 309: def filter_by_associations_conditions_expression(obj) 310: ds = filter_by_associations_conditions_dataset.where(filter_by_associations_conditions_subquery_conditions(obj)) 311: {filter_by_associations_conditions_key=>ds} 312: end
Whether to handle silent modification failure when adding/removing associated records, false by default.
# File lib/sequel/model/associations.rb, line 316 316: def handle_silent_modification_failure? 317: false 318: end
Initialize the associations cache for the current association for the given objects.
# File lib/sequel/model/associations.rb, line 321 321: def initialize_association_cache(objects) 322: name = self[:name] 323: if assign_singular? 324: objects.each{|object| object.associations[name] = nil} 325: else 326: objects.each{|object| object.associations[name] = []} 327: end 328: end
The limit and offset for this association (returned as a two element array).
# File lib/sequel/model/associations.rb, line 331 331: def limit_and_offset 332: if (v = self[:limit]).is_a?(Array) 333: v 334: else 335: [v, nil] 336: end 337: end
Whether the associated object needs a primary key to be added/removed, false by default.
# File lib/sequel/model/associations.rb, line 341 341: def need_associated_primary_key? 342: false 343: 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 347 347: def placeholder_loader 348: if use_placeholder_loader? 349: cached_fetch(:placeholder_loader) do 350: Sequel::Dataset::PlaceholderLiteralizer.loader(associated_dataset) do |pl, ds| 351: ds.where(*predicate_keys.map{|k| SQL::BooleanExpression.new('=''=', k, pl.arg)}) 352: end 353: end 354: end 355: end
The values that predicate_keys should match for objects to be associated.
# File lib/sequel/model/associations.rb, line 363 363: def predicate_key_values(object) 364: predicate_key_methods.map{|k| object.get_column_value(k)} 365: end
The keys to use for loading of the regular dataset, as an array.
# File lib/sequel/model/associations.rb, line 358 358: def predicate_keys 359: cached_fetch(:predicate_keys){Array(predicate_key)} 360: 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 370 370: def qualify(table, col) 371: transform(col) do |k| 372: case k 373: when Symbol, SQL::Identifier 374: SQL::QualifiedIdentifier.new(table, k) 375: else 376: Sequel::Qualifier.new(self[:model].dataset, table).transform(k) 377: end 378: end 379: end
Qualify col with the associated model‘s table name.
# File lib/sequel/model/associations.rb, line 382 382: def qualify_assoc(col) 383: qualify(associated_class.table_name, col) 384: end
Qualify col with the current model‘s table name.
# File lib/sequel/model/associations.rb, line 387 387: def qualify_cur(col) 388: qualify(self[:model].table_name, col) 389: 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 397 397: def reciprocal 398: cached_fetch(:reciprocal) do 399: possible_recips = [] 400: 401: associated_class.all_association_reflections.each do |assoc_reflect| 402: if reciprocal_association?(assoc_reflect) 403: possible_recips << assoc_reflect 404: end 405: end 406: 407: if possible_recips.length == 1 408: cached_set(:reciprocal_type, possible_recips.first[:type]) if ambiguous_reciprocal_type? 409: possible_recips.first[:name] 410: end 411: end 412: 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 416 416: def reciprocal_array? 417: true 418: end
Name symbol for the remove_all_ association method
# File lib/sequel/model/associations.rb, line 421 421: def remove_all_method 422: 423: "remove_all_#{self[:name]}" 424: 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 427 427: def remove_before_destroy? 428: true 429: end
Name symbol for the remove_ association method
# File lib/sequel/model/associations.rb, line 432 432: def remove_method 433: 434: "remove_#{singularize(self[:name])}" 435: 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 437 437: def remove_should_check_existing? 438: false 439: end
Whether this association returns an array of objects instead of a single object, true by default.
# File lib/sequel/model/associations.rb, line 443 443: def returns_array? 444: true 445: end
Whether to set the reciprocal association to self when loading associated records, false by default.
# File lib/sequel/model/associations.rb, line 454 454: def set_reciprocal_to_self? 455: false 456: end
Name symbol for the setter association method
# File lib/sequel/model/associations.rb, line 459 459: def setter_method 460: 461: "#{self[:name]}=" 462: end