Class: Sequel::Model::Associations::AssociationReflection

Inherits:
Hash
  • Object
show all
Includes:
Inflections
Defined in:
lib/sequel/model/associations.rb

Overview

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.

Constant Summary collapse

ASSOCIATION_DATASET_PROC = 
proc{|r| r.association_dataset_for(self)}

Constants included from Inflections

Inflections::CAMELIZE_CONVERT_REGEXP, Inflections::CAMELIZE_MODULE_REGEXP, Inflections::DASH, Inflections::DEMODULIZE_CONVERT_REGEXP, Inflections::EMPTY_STRING, Inflections::SLASH, Inflections::UNDERSCORE, Inflections::UNDERSCORE_CONVERT_REGEXP1, Inflections::UNDERSCORE_CONVERT_REGEXP2, Inflections::UNDERSCORE_CONVERT_REPLACE, Inflections::UNDERSCORE_MODULE_REGEXP, Inflections::VALID_CONSTANT_NAME_REGEXP

Instance Method Summary collapse

Methods included from Inflections

clear, irregular, plural, singular, uncountable

Methods inherited from Hash

#&, #case, #hstore, #pg_json, #pg_jsonb, #sql_expr, #sql_negate, #sql_or, #|, #~

Instance Method Details

#_add_method ⇒ Object

Name symbol for the _add internal association method



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# File 'lib/sequel/model/associations.rb', line 25

def _add_method
  :"_add_#{singularize(self[:name])}"
end

#_remove_all_method ⇒ Object

Name symbol for the _remove_all internal association method



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# File 'lib/sequel/model/associations.rb', line 30

def _remove_all_method
  :"_remove_all_#{self[:name]}"
end

#_remove_method ⇒ Object

Name symbol for the _remove internal association method



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# File 'lib/sequel/model/associations.rb', line 35

def _remove_method
  :"_remove_#{singularize(self[:name])}"
end

#_setter_method ⇒ Object

Name symbol for the _setter association method



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# File 'lib/sequel/model/associations.rb', line 40

def _setter_method
  :"_#{self[:name]}="
end

#add_method ⇒ Object

Name symbol for the add association method



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# File 'lib/sequel/model/associations.rb', line 45

def add_method
  :"add_#{singularize(self[:name])}"
end

#apply_dataset_changes(ds) ⇒ Object

Apply all non-instance specific changes to the given dataset and return it.



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# 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

#apply_distinct_on_eager_limit_strategy(ds) ⇒ Object

Use DISTINCT ON and ORDER BY clauses to limit the results to the first record with matching keys.



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# 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_eager_dataset_changes(ds) ⇒ Object

Apply all non-instance specific changes and the eager_block option to the given dataset and return it.



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# 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_eager_graph_limit_strategy(strategy, ds) ⇒ Object

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.



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# 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_eager_limit_strategy(ds, strategy = eager_limit_strategy) ⇒ Object

Apply an eager limit strategy to the dataset, or return the dataset unmodified if it doesn’t need an eager limit strategy.



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# 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

#apply_ruby_eager_limit_strategy(rows) ⇒ Object

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.



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# File 'lib/sequel/model/associations.rb', line 146

def apply_ruby_eager_limit_strategy(rows)
  if eager_limit_strategy == :ruby
    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
end

#apply_window_function_eager_limit_strategy(ds) ⇒ Object

Use a window function to limit the results of the eager loading dataset.



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# 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

#assign_singular? ⇒ Boolean

Whether the associations cache should use an array when storing the associated records during eager loading.

Returns:

  • (Boolean) 


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# File 'lib/sequel/model/associations.rb', line 161

def assign_singular?
  !returns_array?
end

#associated_class ⇒ Object

The class associated to the current model class via this association



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# File 'lib/sequel/model/associations.rb', line 55

def associated_class
  cached_fetch(:class){constantize(self[:class_name])}
end

#associated_dataset ⇒ Object

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.



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# File 'lib/sequel/model/associations.rb', line 62

def associated_dataset
  cached_fetch(:_dataset){apply_dataset_changes(_associated_dataset)}
end

#association_dataset_for(object) ⇒ Object

Return an dataset that will load the appropriate associated objects for the given object using this association.



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# File 'lib/sequel/model/associations.rb', line 198

def association_dataset_for(object)
  associated_dataset.where(predicate_keys.zip(predicate_key_values(object)))
end

#association_dataset_proc ⇒ Object

Proc used to create the association dataset method.



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# File 'lib/sequel/model/associations.rb', line 204

def association_dataset_proc
  ASSOCIATION_DATASET_PROC
end

#association_method ⇒ Object

Name symbol for association method, the same as the name of the association.



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# File 'lib/sequel/model/associations.rb', line 50

def association_method
  self[:name]
end

#can_have_associated_objects?(obj) ⇒ Boolean

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.

Returns:

  • (Boolean) 


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# File 'lib/sequel/model/associations.rb', line 168

def can_have_associated_objects?(obj)
  true
end

#cloneable?(ref) ⇒ Boolean

Whether you are able to clone from the given association type to the current association type, true by default only if the types match.

Returns:

  • (Boolean) 


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# File 'lib/sequel/model/associations.rb', line 174

def cloneable?(ref)
  ref[:type] == self[:type]
end

#dataset_method ⇒ Object

Name symbol for the dataset association method



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# File 'lib/sequel/model/associations.rb', line 179

def dataset_method
  :"#{self[:name]}_dataset"
end

#dataset_need_primary_key? ⇒ Boolean

Whether the dataset needs a primary key to function, true by default.

Returns:

  • (Boolean) 


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# File 'lib/sequel/model/associations.rb', line 184

def dataset_need_primary_key?
  true
end

#delete_row_number_column(ds = associated_dataset) ⇒ Object

Return the symbol used for the row number column if the window function eager limit strategy is being used, or nil otherwise.



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# File 'lib/sequel/model/associations.rb', line 190

def delete_row_number_column(ds=associated_dataset)
  if eager_limit_strategy == :window_function
    ds.row_number_column 
  end
end

#eager_graph_lazy_dataset? ⇒ Boolean

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.

Returns:

  • (Boolean) 


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# File 'lib/sequel/model/associations.rb', line 289

def eager_graph_lazy_dataset?
  true
end

#eager_graph_limit_strategy(strategy) ⇒ Object

The eager_graph limit strategy to use for this dataset



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# File 'lib/sequel/model/associations.rb', line 209

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

#eager_limit_strategy ⇒ Object

The eager limit strategy to use for this dataset.



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# File 'lib/sequel/model/associations.rb', line 226

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_results(eo, &block) ⇒ Object

Eager load the associated objects using the hash of eager options, yielding each row to the block.



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# File 'lib/sequel/model/associations.rb', line 241

def eager_load_results(eo, &block)
  rows = eo[:rows]
  initialize_association_cache(rows) unless eo[:initialize_rows] == false
  strategy = eager_limit_strategy
  cascade = eo[:associations]

  if eo[:eager_block] || eo[:loader] == false
    strategy = true_eager_graph_limit_strategy if strategy == :union
    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 "
    eo[:id_map].keys.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(eo[:id_map].keys)
  end

  objects.each(&block)
  apply_ruby_eager_limit_strategy(rows)
end

#eager_loader_key ⇒ Object

The key to use for the key hash when eager loading



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# File 'lib/sequel/model/associations.rb', line 271

def eager_loader_key
  self[:eager_loader_key]
end

#eager_loading_predicate_key ⇒ Object

Alias of predicate_key, only for backwards compatibility.



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# File 'lib/sequel/model/associations.rb', line 282

def eager_loading_predicate_key
  predicate_key
end

#eager_loading_use_associated_key? ⇒ Boolean

By default associations do not need to select a key in an associated table to eagerly load.

Returns:

  • (Boolean) 


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# File 'lib/sequel/model/associations.rb', line 277

def eager_loading_use_associated_key?
  false
end

#filter_by_associations_add_conditions? ⇒ Boolean

Whether additional conditions should be added when using the filter by associations support.

Returns:

  • (Boolean) 


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# File 'lib/sequel/model/associations.rb', line 295

def filter_by_associations_add_conditions?
  self[:conditions] || self[:eager_block] || self[:limit]
end

#filter_by_associations_conditions_expression(obj) ⇒ Object

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.



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# File 'lib/sequel/model/associations.rb', line 303

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

#handle_silent_modification_failure? ⇒ Boolean

Whether to handle silent modification failure when adding/removing associated records, false by default.

Returns:

  • (Boolean) 


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# File 'lib/sequel/model/associations.rb', line 310

def handle_silent_modification_failure?
  false
end

#initialize_association_cache(objects) ⇒ Object

Initialize the associations cache for the current association for the given objects.



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# File 'lib/sequel/model/associations.rb', line 315

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

#limit_and_offset ⇒ Object

The limit and offset for this association (returned as a two element array).



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# File 'lib/sequel/model/associations.rb', line 325

def limit_and_offset
  if (v = self[:limit]).is_a?(Array)
    v
  else
    [v, nil]
  end
end

#need_associated_primary_key? ⇒ Boolean

Whether the associated object needs a primary key to be added/removed, false by default.

Returns:

  • (Boolean) 


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# File 'lib/sequel/model/associations.rb', line 335

def need_associated_primary_key?
  false
end

#placeholder_loader ⇒ Object

A placeholder literalizer that can be used to lazily load the association. If one can’t be used, returns nil.



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# File 'lib/sequel/model/associations.rb', line 341

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

#predicate_key_values(object) ⇒ Object

The values that predicate_keys should match for objects to be associated.



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# File 'lib/sequel/model/associations.rb', line 357

def predicate_key_values(object)
  predicate_key_methods.map{|k| object.send(k)}
end

#predicate_keys ⇒ Object

The keys to use for loading of the regular dataset, as an array.



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# File 'lib/sequel/model/associations.rb', line 352

def predicate_keys
  cached_fetch(:predicate_keys){Array(predicate_key)}
end

#qualify(table, col) ⇒ Object

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.



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# File 'lib/sequel/model/associations.rb', line 364

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_assoc(col) ⇒ Object

Qualify col with the associated model’s table name.



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# File 'lib/sequel/model/associations.rb', line 376

def qualify_assoc(col)
  qualify(associated_class.table_name, col)
end

#qualify_cur(col) ⇒ Object

Qualify col with the current model’s table name.



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# File 'lib/sequel/model/associations.rb', line 381

def qualify_cur(col)
  qualify(self[:model].table_name, col)
end

#reciprocal ⇒ Object

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.



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# File 'lib/sequel/model/associations.rb', line 391

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

#reciprocal_array? ⇒ Boolean

Whether the reciprocal of this association returns an array of objects instead of a single object, true by default.

Returns:

  • (Boolean) 


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# File 'lib/sequel/model/associations.rb', line 410

def reciprocal_array?
  true
end

#remove_all_method ⇒ Object

Name symbol for the remove_all_ association method



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# File 'lib/sequel/model/associations.rb', line 415

def remove_all_method
  :"remove_all_#{self[:name]}"
end

#remove_before_destroy? ⇒ Boolean

Whether associated objects need to be removed from the association before being destroyed in order to preserve referential integrity.

Returns:

  • (Boolean) 


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# File 'lib/sequel/model/associations.rb', line 421

def remove_before_destroy?
  true
end

#remove_method ⇒ Object

Name symbol for the remove_ association method



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# File 'lib/sequel/model/associations.rb', line 426

def remove_method
  :"remove_#{singularize(self[:name])}"
end

#remove_should_check_existing? ⇒ Boolean

Whether to check that an object to be disassociated is already associated to this object, false by default.

Returns:

  • (Boolean) 


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# File 'lib/sequel/model/associations.rb', line 431

def remove_should_check_existing?
  false
end

#returns_array? ⇒ Boolean

Whether this association returns an array of objects instead of a single object, true by default.

Returns:

  • (Boolean) 


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# File 'lib/sequel/model/associations.rb', line 437

def returns_array?
  true
end

#select ⇒ Object

The columns to select when loading the association.



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# File 'lib/sequel/model/associations.rb', line 442

def select
  self[:select]
end

#set_reciprocal_to_self? ⇒ Boolean

Whether to set the reciprocal association to self when loading associated records, false by default.

Returns:

  • (Boolean) 


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# File 'lib/sequel/model/associations.rb', line 448

def set_reciprocal_to_self?
  false
end

#setter_method ⇒ Object

Name symbol for the setter association method



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# File 'lib/sequel/model/associations.rb', line 453

def setter_method
  :"#{self[:name]}="
end

#slice_range ⇒ Object

The range used for slicing when using the :ruby eager limit strategy.



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# File 'lib/sequel/model/associations.rb', line 458

def slice_range
  limit, offset = limit_and_offset
  if limit || offset
    (offset||0)..(limit ? (offset||0)+limit-1 : -1)
  end
end