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Instance Public methods
column_defaults()

Returns a hash where the keys are column names and the values are default values when instantiating the Active Record object for this table.

# File activerecord/lib/active_record/model_schema.rb, line 376
def column_defaults
  load_schema
  @column_defaults ||= _default_attributes.to_hash
end
column_names()

Returns an array of column names as strings.

# File activerecord/lib/active_record/model_schema.rb, line 387
def column_names
  @column_names ||= columns.map(&:name)
end
columns()
# File activerecord/lib/active_record/model_schema.rb, line 340
def columns
  load_schema
  @columns ||= columns_hash.values
end
compute_table_name()

Computes and returns a table name according to default conventions.

# File activerecord/lib/active_record/model_schema.rb, line 503
def compute_table_name
  if base_class?
    # Nested classes are prefixed with singular parent table name.
    if parent < Base && !parent.abstract_class?
      contained = parent.table_name
      contained = contained.singularize if parent.pluralize_table_names
      contained += "_"
    end

    "#{full_table_name_prefix}#{contained}#{undecorated_table_name(name)}#{full_table_name_suffix}"
  else
    # STI subclasses always use their superclass' table.
    base_class.table_name
  end
end
content_columns()

Returns an array of column objects where the primary id, all columns ending in “_id” or “_count”, and columns used for single table inheritance have been removed.

# File activerecord/lib/active_record/model_schema.rb, line 393
def content_columns
  @content_columns ||= columns.reject do |c|
    c.name == primary_key ||
    c.name == inheritance_column ||
    c.name.end_with?("_id") ||
    c.name.end_with?("_count")
  end
end
ignored_columns()

The list of columns names the model should ignore. Ignored columns won't have attribute accessors defined, and won't be referenced in SQL queries.

# File activerecord/lib/active_record/model_schema.rb, line 264
def ignored_columns
  if defined?(@ignored_columns)
    @ignored_columns
  else
    superclass.ignored_columns
  end
end
ignored_columns=(columns)

Sets the columns names the model should ignore. Ignored columns won't have attribute accessors defined, and won't be referenced in SQL queries.

# File activerecord/lib/active_record/model_schema.rb, line 274
def ignored_columns=(columns)
  @ignored_columns = columns.map(&:to_s)
end
inheritance_column()

Defines the name of the table column which will store the class name on single-table inheritance situations.

The default inheritance column name is type, which means it's a reserved word inside Active Record. To be able to use single-table inheritance with another column name, or to use the column type in your own model for something else, you can set inheritance_column:

self.inheritance_column = 'zoink'
# File activerecord/lib/active_record/model_schema.rb, line 252
def inheritance_column
  (@inheritance_column ||= nil) || superclass.inheritance_column
end
inheritance_column=(value)

Sets the value of #inheritance_column

# File activerecord/lib/active_record/model_schema.rb, line 257
def inheritance_column=(value)
  @inheritance_column = value.to_s
  @explicit_inheritance_column = true
end
inherited(child_class)
# File activerecord/lib/active_record/model_schema.rb, line 445
def inherited(child_class)
  super
  child_class.initialize_load_schema_monitor
end
initialize_load_schema_monitor()
# File activerecord/lib/active_record/model_schema.rb, line 439
def initialize_load_schema_monitor
  @load_schema_monitor = Monitor.new
end
load_schema()
# File activerecord/lib/active_record/model_schema.rb, line 454
      def load_schema
        return if schema_loaded?
        @load_schema_monitor.synchronize do
          return if defined?(@columns_hash) && @columns_hash

          load_schema!

          @schema_loaded = true
        end
      end

      def load_schema!
        @columns_hash = connection.schema_cache.columns_hash(table_name).except(*ignored_columns)
        @columns_hash.each do |name, column|
          define_attribute(
            name,
            connection.lookup_cast_type_from_column(column),
            default: column.default,
            user_provided_default: false
          )
        end
      end

      def reload_schema_from_cache
        @arel_table = nil
        @column_names = nil
        @attribute_types = nil
        @content_columns = nil
        @default_attributes = nil
        @column_defaults = nil
        @inheritance_column = nil unless defined?(@explicit_inheritance_column) && @explicit_inheritance_column
        @attributes_builder = nil
        @columns = nil
        @columns_hash = nil
        @schema_loaded = false
        @attribute_names = nil
        @yaml_encoder = nil
        direct_descendants.each do |descendant|
          descendant.send(:reload_schema_from_cache)
        end
      end

      # Guesses the table name, but does not decorate it with prefix and suffix information.
      def undecorated_table_name(class_name = base_class.name)
        table_name = class_name.to_s.demodulize.underscore
        pluralize_table_names ? table_name.pluralize : table_name
      end

      # Computes and returns a table name according to default conventions.
      def compute_table_name
        if base_class?
          # Nested classes are prefixed with singular parent table name.
          if parent < Base && !parent.abstract_class?
            contained = parent.table_name
            contained = contained.singularize if parent.pluralize_table_names
            contained += "_"
          end

          "#{full_table_name_prefix}#{contained}#{undecorated_table_name(name)}#{full_table_name_suffix}"
        else
          # STI subclasses always use their superclass' table.
          base_class.table_name
        end
      end
  end
end
load_schema!()
# File activerecord/lib/active_record/model_schema.rb, line 465
def load_schema!
  @columns_hash = connection.schema_cache.columns_hash(table_name).except(*ignored_columns)
  @columns_hash.each do |name, column|
    define_attribute(
      name,
      connection.lookup_cast_type_from_column(column),
      default: column.default,
      user_provided_default: false
    )
  end
end
next_sequence_value()

Returns the next value that will be used as the primary key on an insert statement.

# File activerecord/lib/active_record/model_schema.rb, line 318
def next_sequence_value
  connection.next_sequence_value(sequence_name)
end
prefetch_primary_key?()

Determines if the primary key values should be selected from their corresponding sequence before the insert statement.

# File activerecord/lib/active_record/model_schema.rb, line 312
def prefetch_primary_key?
  connection.prefetch_primary_key?(table_name)
end
protected_environments()

The array of names of environments where destructive actions should be prohibited. By default, the value is ["production"].

# File activerecord/lib/active_record/model_schema.rb, line 230
def protected_environments
  if defined?(@protected_environments)
    @protected_environments
  else
    superclass.protected_environments
  end
end
protected_environments=(environments)

Sets an array of names of environments where destructive actions should be prohibited.

# File activerecord/lib/active_record/model_schema.rb, line 239
def protected_environments=(environments)
  @protected_environments = environments.map(&:to_s)
end
quoted_table_name()

Returns a quoted version of the table name, used to construct SQL statements.

# File activerecord/lib/active_record/model_schema.rb, line 205
def quoted_table_name
  @quoted_table_name ||= connection.quote_table_name(table_name)
end
reload_schema_from_cache()
# File activerecord/lib/active_record/model_schema.rb, line 477
def reload_schema_from_cache
  @arel_table = nil
  @column_names = nil
  @attribute_types = nil
  @content_columns = nil
  @default_attributes = nil
  @column_defaults = nil
  @inheritance_column = nil unless defined?(@explicit_inheritance_column) && @explicit_inheritance_column
  @attributes_builder = nil
  @columns = nil
  @columns_hash = nil
  @schema_loaded = false
  @attribute_names = nil
  @yaml_encoder = nil
  direct_descendants.each do |descendant|
    descendant.send(:reload_schema_from_cache)
  end
end
reset_column_information()

Resets all the cached information about columns, which will cause them to be reloaded on the next request.

The most common usage pattern for this method is probably in a migration, when just after creating a table you want to populate it with some default values, eg:

class CreateJobLevels < ActiveRecord::Migration[5.0]
  def up
    create_table :job_levels do |t|
      t.integer :id
      t.string :name

      t.timestamps
    end

    JobLevel.reset_column_information
    %w{assistant executive manager director}.each do |type|
      JobLevel.create(name: type)
    end
  end

  def down
    drop_table :job_levels
  end
end
# File activerecord/lib/active_record/model_schema.rb, line 428
def reset_column_information
  connection.clear_cache!
  ([self] + descendants).each(&:undefine_attribute_methods)
  connection.schema_cache.clear_data_source_cache!(table_name)

  reload_schema_from_cache
  initialize_find_by_cache
end
schema_loaded?()
# File activerecord/lib/active_record/model_schema.rb, line 450
def schema_loaded?
  defined?(@schema_loaded) && @schema_loaded
end
sequence_name()
# File activerecord/lib/active_record/model_schema.rb, line 278
def sequence_name
  if base_class?
    @sequence_name ||= reset_sequence_name
  else
    (@sequence_name ||= nil) || base_class.sequence_name
  end
end
sequence_name=(value)

Sets the name of the sequence to use when generating ids to the given value, or (if the value is nil or false) to the value returned by the given block. This is required for Oracle and is useful for any database which relies on sequences for primary key generation.

If a sequence name is not explicitly set when using Oracle, it will default to the commonly used pattern of: #{table_name}_seq

If a sequence name is not explicitly set when using PostgreSQL, it will discover the sequence corresponding to your primary key for you.

class Project < ActiveRecord::Base
  self.sequence_name = "projectseq"   # default would have been "project_seq"
end
# File activerecord/lib/active_record/model_schema.rb, line 305
def sequence_name=(value)
  @sequence_name          = value.to_s
  @explicit_sequence_name = true
end
table_exists?()

Indicates whether the table associated with this class exists

# File activerecord/lib/active_record/model_schema.rb, line 323
def table_exists?
  connection.schema_cache.data_source_exists?(table_name)
end
table_name()

Guesses the table name (in forced lower-case) based on the name of the class in the inheritance hierarchy descending directly from ActiveRecord::Base. So if the hierarchy looks like: Reply < Message < ActiveRecord::Base, then Message is used to guess the table name even when called on Reply. The rules used to do the guess are handled by the Inflector class in Active Support, which knows almost all common English inflections. You can add new inflections in config/initializers/inflections.rb.

Nested classes are given table names prefixed by the singular form of the parent's table name. Enclosing modules are not considered.

Examples

class Invoice < ActiveRecord::Base
end

file                  class               table_name
invoice.rb            Invoice             invoices

class Invoice < ActiveRecord::Base
  class Lineitem < ActiveRecord::Base
  end
end

file                  class               table_name
invoice.rb            Invoice::Lineitem   invoice_lineitems

module Invoice
  class Lineitem < ActiveRecord::Base
  end
end

file                  class               table_name
invoice/lineitem.rb   Invoice::Lineitem   lineitems

Additionally, the class-level table_name_prefix is prepended and the table_name_suffix is appended. So if you have “myapp_” as a prefix, the table name guess for an Invoice class becomes “myapp_invoices”. Invoice::Lineitem becomes “myapp_invoice_lineitems”.

You can also set your own table name explicitly:

class Mouse < ActiveRecord::Base
  self.table_name = "mice"
end
# File activerecord/lib/active_record/model_schema.rb, line 179
def table_name
  reset_table_name unless defined?(@table_name)
  @table_name
end
table_name=(value)

Sets the table name explicitly. Example:

class Project < ActiveRecord::Base
  self.table_name = "project"
end
# File activerecord/lib/active_record/model_schema.rb, line 189
      def table_name=(value)
        value = value && value.to_s

        if defined?(@table_name)
          return if value == @table_name
          reset_column_information if connected?
        end

        @table_name        = value
        @quoted_table_name = nil
        @arel_table        = nil
        @sequence_name     = nil unless defined?(@explicit_sequence_name) && @explicit_sequence_name
        @predicate_builder = nil
      end

      # Returns a quoted version of the table name, used to construct SQL statements.
      def quoted_table_name
        @quoted_table_name ||= connection.quote_table_name(table_name)
      end

      # Computes the table name, (re)sets it internally, and returns it.
      def reset_table_name #:nodoc:
        self.table_name = if abstract_class?
          superclass == Base ? nil : superclass.table_name
        elsif superclass.abstract_class?
          superclass.table_name || compute_table_name
        else
          compute_table_name
        end
      end

      def full_table_name_prefix #:nodoc:
        (parents.detect { |p| p.respond_to?(:table_name_prefix) } || self).table_name_prefix
      end

      def full_table_name_suffix #:nodoc:
        (parents.detect { |p| p.respond_to?(:table_name_suffix) } || self).table_name_suffix
      end

      # The array of names of environments where destructive actions should be prohibited. By default,
      # the value is <tt>["production"]</tt>.
      def protected_environments
        if defined?(@protected_environments)
          @protected_environments
        else
          superclass.protected_environments
        end
      end

      # Sets an array of names of environments where destructive actions should be prohibited.
      def protected_environments=(environments)
        @protected_environments = environments.map(&:to_s)
      end

      # Defines the name of the table column which will store the class name on single-table
      # inheritance situations.
      #
      # The default inheritance column name is +type+, which means it's a
      # reserved word inside Active Record. To be able to use single-table
      # inheritance with another column name, or to use the column +type+ in
      # your own model for something else, you can set +inheritance_column+:
      #
      #     self.inheritance_column = 'zoink'
      def inheritance_column
        (@inheritance_column ||= nil) || superclass.inheritance_column
      end

      # Sets the value of inheritance_column
      def inheritance_column=(value)
        @inheritance_column = value.to_s
        @explicit_inheritance_column = true
      end

      # The list of columns names the model should ignore. Ignored columns won't have attribute
      # accessors defined, and won't be referenced in SQL queries.
      def ignored_columns
        if defined?(@ignored_columns)
          @ignored_columns
        else
          superclass.ignored_columns
        end
      end

      # Sets the columns names the model should ignore. Ignored columns won't have attribute
      # accessors defined, and won't be referenced in SQL queries.
      def ignored_columns=(columns)
        @ignored_columns = columns.map(&:to_s)
      end

      def sequence_name
        if base_class?
          @sequence_name ||= reset_sequence_name
        else
          (@sequence_name ||= nil) || base_class.sequence_name
        end
      end

      def reset_sequence_name #:nodoc:
        @explicit_sequence_name = false
        @sequence_name          = connection.default_sequence_name(table_name, primary_key)
      end

      # Sets the name of the sequence to use when generating ids to the given
      # value, or (if the value is +nil+ or +false+) to the value returned by the
      # given block. This is required for Oracle and is useful for any
      # database which relies on sequences for primary key generation.
      #
      # If a sequence name is not explicitly set when using Oracle,
      # it will default to the commonly used pattern of: #{table_name}_seq
      #
      # If a sequence name is not explicitly set when using PostgreSQL, it
      # will discover the sequence corresponding to your primary key for you.
      #
      #   class Project < ActiveRecord::Base
      #     self.sequence_name = "projectseq"   # default would have been "project_seq"
      #   end
      def sequence_name=(value)
        @sequence_name          = value.to_s
        @explicit_sequence_name = true
      end

      # Determines if the primary key values should be selected from their
      # corresponding sequence before the insert statement.
      def prefetch_primary_key?
        connection.prefetch_primary_key?(table_name)
      end

      # Returns the next value that will be used as the primary key on
      # an insert statement.
      def next_sequence_value
        connection.next_sequence_value(sequence_name)
      end

      # Indicates whether the table associated with this class exists
      def table_exists?
        connection.schema_cache.data_source_exists?(table_name)
      end

      def attributes_builder # :nodoc:
        unless defined?(@attributes_builder) && @attributes_builder
          defaults = _default_attributes.except(*(column_names - [primary_key]))
          @attributes_builder = ActiveModel::AttributeSet::Builder.new(attribute_types, defaults)
        end
        @attributes_builder
      end

      def columns_hash # :nodoc:
        load_schema
        @columns_hash
      end

      def columns
        load_schema
        @columns ||= columns_hash.values
      end

      def attribute_types # :nodoc:
        load_schema
        @attribute_types ||= Hash.new(Type.default_value)
      end

      def yaml_encoder # :nodoc:
        @yaml_encoder ||= ActiveModel::AttributeSet::YAMLEncoder.new(attribute_types)
      end

      # Returns the type of the attribute with the given name, after applying
      # all modifiers. This method is the only valid source of information for
      # anything related to the types of a model's attributes. This method will
      # access the database and load the model's schema if it is required.
      #
      # The return value of this method will implement the interface described
      # by ActiveModel::Type::Value (though the object itself may not subclass
      # it).
      #
      # +attr_name+ The name of the attribute to retrieve the type for. Must be
      # a string or a symbol.
      def type_for_attribute(attr_name, &block)
        attr_name = attr_name.to_s
        if block
          attribute_types.fetch(attr_name, &block)
        else
          attribute_types[attr_name]
        end
      end

      # Returns a hash where the keys are column names and the values are
      # default values when instantiating the Active Record object for this table.
      def column_defaults
        load_schema
        @column_defaults ||= _default_attributes.to_hash
      end

      def _default_attributes # :nodoc:
        load_schema
        @default_attributes ||= ActiveModel::AttributeSet.new({})
      end

      # Returns an array of column names as strings.
      def column_names
        @column_names ||= columns.map(&:name)
      end

      # Returns an array of column objects where the primary id, all columns ending in "_id" or "_count",
      # and columns used for single table inheritance have been removed.
      def content_columns
        @content_columns ||= columns.reject do |c|
          c.name == primary_key ||
          c.name == inheritance_column ||
          c.name.end_with?("_id") ||
          c.name.end_with?("_count")
        end
      end

      # Resets all the cached information about columns, which will cause them
      # to be reloaded on the next request.
      #
      # The most common usage pattern for this method is probably in a migration,
      # when just after creating a table you want to populate it with some default
      # values, eg:
      #
      #  class CreateJobLevels < ActiveRecord::Migration[5.0]
      #    def up
      #      create_table :job_levels do |t|
      #        t.integer :id
      #        t.string :name
      #
      #        t.timestamps
      #      end
      #
      #      JobLevel.reset_column_information
      #      %w{assistant executive manager director}.each do |type|
      #        JobLevel.create(name: type)
      #      end
      #    end
      #
      #    def down
      #      drop_table :job_levels
      #    end
      #  end
      def reset_column_information
        connection.clear_cache!
        ([self] + descendants).each(&:undefine_attribute_methods)
        connection.schema_cache.clear_data_source_cache!(table_name)

        reload_schema_from_cache
        initialize_find_by_cache
      end

      protected

        def initialize_load_schema_monitor
          @load_schema_monitor = Monitor.new
        end

      private

        def inherited(child_class)
          super
          child_class.initialize_load_schema_monitor
        end

        def schema_loaded?
          defined?(@schema_loaded) && @schema_loaded
        end

        def load_schema
          return if schema_loaded?
          @load_schema_monitor.synchronize do
            return if defined?(@columns_hash) && @columns_hash

            load_schema!

            @schema_loaded = true
          end
        end

        def load_schema!
          @columns_hash = connection.schema_cache.columns_hash(table_name).except(*ignored_columns)
          @columns_hash.each do |name, column|
            define_attribute(
              name,
              connection.lookup_cast_type_from_column(column),
              default: column.default,
              user_provided_default: false
            )
          end
        end

        def reload_schema_from_cache
          @arel_table = nil
          @column_names = nil
          @attribute_types = nil
          @content_columns = nil
          @default_attributes = nil
          @column_defaults = nil
          @inheritance_column = nil unless defined?(@explicit_inheritance_column) && @explicit_inheritance_column
          @attributes_builder = nil
          @columns = nil
          @columns_hash = nil
          @schema_loaded = false
          @attribute_names = nil
          @yaml_encoder = nil
          direct_descendants.each do |descendant|
            descendant.send(:reload_schema_from_cache)
          end
        end

        # Guesses the table name, but does not decorate it with prefix and suffix information.
        def undecorated_table_name(class_name = base_class.name)
          table_name = class_name.to_s.demodulize.underscore
          pluralize_table_names ? table_name.pluralize : table_name
        end

        # Computes and returns a table name according to default conventions.
        def compute_table_name
          if base_class?
            # Nested classes are prefixed with singular parent table name.
            if parent < Base && !parent.abstract_class?
              contained = parent.table_name
              contained = contained.singularize if parent.pluralize_table_names
              contained += "_"
            end

            "#{full_table_name_prefix}#{contained}#{undecorated_table_name(name)}#{full_table_name_suffix}"
          else
            # STI subclasses always use their superclass' table.
            base_class.table_name
          end
        end
    end
  end
end
type_for_attribute(attr_name, &block)

Returns the type of the attribute with the given name, after applying all modifiers. This method is the only valid source of information for anything related to the types of a model's attributes. This method will access the database and load the model's schema if it is required.

The return value of this method will implement the interface described by ActiveModel::Type::Value (though the object itself may not subclass it).

attr_name The name of the attribute to retrieve the type for. Must be a string or a symbol.

# File activerecord/lib/active_record/model_schema.rb, line 365
def type_for_attribute(attr_name, &block)
  attr_name = attr_name.to_s
  if block
    attribute_types.fetch(attr_name, &block)
  else
    attribute_types[attr_name]
  end
end
undecorated_table_name(class_name = base_class.name)

Guesses the table name, but does not decorate it with prefix and suffix information.

# File activerecord/lib/active_record/model_schema.rb, line 497
def undecorated_table_name(class_name = base_class.name)
  table_name = class_name.to_s.demodulize.underscore
  pluralize_table_names ? table_name.pluralize : table_name
end