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)}
FINALIZE_SETTINGS =

Map of methods to cache keys used for finalizing associations.

{
  :associated_class=>:class,
  :associated_dataset=>:_dataset,
  :eager_limit_strategy=>:_eager_limit_strategy,
  :placeholder_loader=>:placeholder_loader,
  :predicate_key=>:predicate_key,
  :predicate_keys=>:predicate_keys,
  :reciprocal=>:reciprocal,
}.freeze

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 36

def _add_method
  self[:_add_method]
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 41

def _remove_all_method
  self[:_remove_all_method]
end

#_remove_method ⇒ Object

Name symbol for the _remove internal association method


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# File 'lib/sequel/model/associations.rb', line 46

def _remove_method
  self[:_remove_method]
end

#_setter_method ⇒ Object

Name symbol for the _setter association method


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# File 'lib/sequel/model/associations.rb', line 51

def _setter_method
  self[:_setter_method]
end

#add_method ⇒ Object

Name symbol for the add association method


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# File 'lib/sequel/model/associations.rb', line 56

def add_method
  self[:add_method]
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 84

def apply_dataset_changes(ds)
  ds = ds.with_extend(AssociationDatasetMethods).clone(:association_reflection => self)
  if exts = self[:reverse_extend]
    ds = ds.with_extend(*exts)
  end
  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

#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 138

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 103

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 113

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, limit_and_offset = limit_and_offset()) ⇒ 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 126

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

#apply_ruby_eager_limit_strategy(rows, limit_and_offset = limit_and_offset()) ⇒ 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 165

def apply_ruby_eager_limit_strategy(rows, limit_and_offset = limit_and_offset())
  name = self[:name]
  return unless range = slice_range(limit_and_offset)
  if returns_array?
    rows.each{|o| o.associations[name] = o.associations[name][range] || []}
  else
    offset = range.begin
    rows.each{|o| o.associations[name] = o.associations[name][offset]}
  end
end

#apply_window_function_eager_limit_strategy(ds, limit_and_offset = limit_and_offset()) ⇒ 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 144

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.function.over(:partition=>predicate_key, :order=>ds.opts[:order]).as(rn)}.from_self
  ds = ds.order(rn) if ds.db.database_type == :mysql
  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 178

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 66

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

#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 79

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 215

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

#association_dataset_proc ⇒ Object

Proc used to create the association dataset method.


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# File 'lib/sequel/model/associations.rb', line 227

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 61

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 185

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 191

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 196

def dataset_method
  self[:dataset_method]
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 201

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 207

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 339

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 232

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 249

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 264

def eager_load_results(eo, &block)
  rows = eo[:rows]
  unless eo[:initialize_rows] == false
    Sequel.synchronize_with(eo[:mutex]){initialize_association_cache(rows)}
  end
  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[:no_results]
    no_results = true
  elsif 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

  Sequel.synchronize_with(eo[:mutex]){objects.each(&block)} unless no_results

  if strategy == :ruby
    apply_ruby_eager_limit_strategy(rows, eager_limit || limit_and_offset)
  end
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 326

def eager_loader_key
  self[:eager_loader_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 332

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 345

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 353

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 ⇒ Object

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.


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# File 'lib/sequel/model/associations.rb', line 361

def finalize
  return unless cache = self[:cache]

  finalizer = proc do |meth, key|
    next if has_key?(key)

    # Allow calling private methods to make sure caching is done appropriately
    send(meth)
    self[key] = cache.delete(key) if cache.has_key?(key)
  end

  finalize_settings.each(&finalizer)

  unless self[:instance_specific]
    finalizer.call(:associated_eager_dataset, :associated_eager_dataset)
    finalizer.call(:filter_by_associations_conditions_dataset, :filter_by_associations_conditions_dataset)
  end

  nil
end

#finalize_settings ⇒ Object 


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# File 'lib/sequel/model/associations.rb', line 392

def finalize_settings
  FINALIZE_SETTINGS
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 398

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 403

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

#inspect ⇒ Object

Show which type of reflection this is, and a guess at what code was used to create the association.


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# File 'lib/sequel/model/associations.rb', line 414

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

#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 425

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 435

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 441

def placeholder_loader
  if use_placeholder_loader?
    cached_fetch(:placeholder_loader) do
      Sequel::Dataset::PlaceholderLiteralizer.loader(associated_dataset) do |pl, ds|
        ds = ds.where(Sequel.&(*predicate_keys.map{|k| SQL::BooleanExpression.new(:'=', k, pl.arg)}))
        if self[:block]
          ds = self[:block].call(ds)
        end
        ds
      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 461

def predicate_key_values(object)
  predicate_key_methods.map{|k| object.get_column_value(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 456

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

#qualify(table, col) ⇒ Object

Qualify col with the given table name.


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# File 'lib/sequel/model/associations.rb', line 466

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_assoc(col) ⇒ Object

Qualify col with the associated model's table name.


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# File 'lib/sequel/model/associations.rb', line 478

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 483

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 493

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 512

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 517

def remove_all_method
  self[:remove_all_method]
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 523

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 528

def remove_method
  self[:remove_method]
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 533

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 539

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 544

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 550

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 555

def setter_method
  self[:setter_method]
end

#slice_range(limit_and_offset = limit_and_offset()) ⇒ Object

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


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# File 'lib/sequel/model/associations.rb', line 560

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