Module: ActiveRecord::AttributeMethods::ClassMethods

### Home Classes Methods

### In Files

- lib/active_record/attribute_methods.rb

### Methods

- #attribute_method?
- #attribute_methods_generated?
- #attribute_names
- #dangerous_attribute_method?
- #define_attribute_methods
- #generated_external_attribute_methods
- #instance_method_already_implemented?
- #method_defined_within?
- #undefine_attribute_methods

### Files

- README.rdoc

### Class/Module Index

Quicksearch

- ActiveRecord
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No matching classes.

# ActiveRecord::AttributeMethods::ClassMethods

### Public Instance Methods

attribute_method?(attribute) click to toggle source

    # File lib/active_record/attribute_methods.rb, line 121
    def attribute_method?(attribute)
      super || (table_exists? && column_names.include?(attribute.to_s.sub(/=$/, '')))
    end

attribute_methods_generated?() click to toggle source

    # File lib/active_record/attribute_methods.rb, line 72
    def attribute_methods_generated?
      @attribute_methods_generated ||= false
    end

attribute_names() click to toggle source

Returns an array of column names as strings if it's not an abstract class and table exists. Otherwise it returns an empty array.

    # File lib/active_record/attribute_methods.rb, line 128
    def attribute_names
      @attribute_names ||= if !abstract_class? && table_exists?
          column_names
        else
          []
        end
    end

dangerous_attribute_method?(name) click to toggle source

A method name is 'dangerous' if it is already defined by Active Record, but not by any ancestors. (So 'puts' is not dangerous but 'save' is.)

    # File lib/active_record/attribute_methods.rb, line 105
    def dangerous_attribute_method?(name)
      method_defined_within?(name, Base)
    end

define_attribute_methods() click to toggle source

Generates all the attribute related methods for columns in the database accessors, mutators and query methods.

    # File lib/active_record/attribute_methods.rb, line 38
    def define_attribute_methods
      unless defined?(@attribute_methods_mutex)
        msg = "It looks like something (probably a gem/plugin) is overriding the "                  "ActiveRecord::Base.inherited method. It is important that this hook executes so "                  "that your models are set up correctly. A workaround has been added to stop this "                  "causing an error in 3.2, but future versions will simply not work if the hook is "                  "overridden. If you are using Kaminari, please upgrade as it is known to have had "                  "this problem.\n\n"
        msg << "The following may help track down the problem:"

        meth = method(:inherited)
        if meth.respond_to?(:source_location)
          msg << " #{meth.source_location.inspect}"
        else
          msg << " #{meth.inspect}"
        end
        msg << "\n\n"

        ActiveSupport::Deprecation.warn(msg)

        @attribute_methods_mutex = Mutex.new
      end

      # Use a mutex; we don't want two thread simaltaneously trying to define
      # attribute methods.
      @attribute_methods_mutex.synchronize do
        return if attribute_methods_generated?
        superclass.define_attribute_methods unless self == base_class
        super(column_names)
        column_names.each { |name| define_external_attribute_method(name) }
        @attribute_methods_generated = true
      end
    end

generated_external_attribute_methods() click to toggle source

We will define the methods as instance methods, but will call them as singleton methods. This allows us to use method_defined? to check if the method exists, which is fast and won't give any false positives from the ancestors (because there are no ancestors).

    # File lib/active_record/attribute_methods.rb, line 80
    def generated_external_attribute_methods
      @generated_external_attribute_methods ||= Module.new { extend self }
    end

instance_method_already_implemented?(method_name) click to toggle source

    # File lib/active_record/attribute_methods.rb, line 89
    def instance_method_already_implemented?(method_name)
      if dangerous_attribute_method?(method_name)
        raise DangerousAttributeError, "#{method_name} is defined by ActiveRecord"
      end

      if superclass == Base
        super
      else
        # If B < A and A defines its own attribute method, then we don't want to overwrite that.
        defined = method_defined_within?(method_name, superclass, superclass.generated_attribute_methods)
        defined && !ActiveRecord::Base.method_defined?(method_name) || super
      end
    end

method_defined_within?(name, klass, sup = klass.superclass) click to toggle source

    # File lib/active_record/attribute_methods.rb, line 109
    def method_defined_within?(name, klass, sup = klass.superclass)
      if klass.method_defined?(name) || klass.private_method_defined?(name)
        if sup.method_defined?(name) || sup.private_method_defined?(name)
          klass.instance_method(name).owner != sup.instance_method(name).owner
        else
          true
        end
      else
        false
      end
    end

undefine_attribute_methods() click to toggle source

    # File lib/active_record/attribute_methods.rb, line 84
    def undefine_attribute_methods
      super
      @attribute_methods_generated = false
    end

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