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AR::AttributeMethods#[] raises AM::AttributeMissingError for missing …

…attributes.

This fixes the following behaviour:

    class Person < ActiveRecord::Base
      belongs_to :company
    end

    # Before:
    person = Person.select('id').first
    person[:name]       # => nil
    person.name         # => ActiveModel::MissingAttributeError: missing_attribute: name
    person[:company_id] # => nil
    person.company      # => nil

    # After:
    person = Person.select('id').first
    person[:name]       # => ActiveModel::MissingAttributeError: missing_attribute: name
    person.name         # => ActiveModel::MissingAttributeError: missing_attribute: name
    person[:company_id] # => ActiveModel::MissingAttributeError: missing_attribute: company_id
    person.company      # => ActiveModel::MissingAttributeError: missing_attribute: company_id

Fixes #5433.
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1 parent e46a8d8 commit 10f6f90d9d1bbc9598bffea90752fc6bd76904cd Francesco Rodriguez committed Oct 28, 2012
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@@ -1,5 +1,28 @@
## Rails 4.0.0 (unreleased) ##
+* `ActiveRecord::AttributeMethods#[]` raises `ActiveModel::MissingAttributeError`
+ error if the given attribute is missing. Fixes #5433.
+
+ class Person < ActiveRecord::Base
+ belongs_to :company
+ end
+
+ # Before:
+ person = Person.select('id').first
+ person[:name] # => nil
+ person.name # => ActiveModel::MissingAttributeError: missing_attribute: name
+ person[:company_id] # => nil
+ person.company # => nil
+
+ # After:
+ person = Person.select('id').first
+ person[:name] # => ActiveModel::MissingAttributeError: missing_attribute: name
+ person.name # => ActiveModel::MissingAttributeError: missing_attribute: name
+ person[:company_id] # => ActiveModel::MissingAttributeError: missing_attribute: company_id
+ person.company # => ActiveModel::MissingAttributeError: missing_attribute: company_id
+
+ *Francesco Rodriguez*
+
* Small binary fields use the `VARBINARY` MySQL type, instead of `TINYBLOB`.
*Victor Costan*
@@ -51,7 +74,7 @@
*Scott Willson*
-* Fix bug where sum(expression) returns string '0' for no matching records
+* Fix bug where sum(expression) returns string '0' for no matching records.
Fixes #7439
*Tim Macfarlane*
@@ -266,16 +266,22 @@ def column_for_attribute(name)
# Returns the value of the attribute identified by <tt>attr_name</tt> after it has been typecast (for example,
# "2004-12-12" in a data column is cast to a date object, like Date.new(2004, 12, 12)).
- # (Alias for the protected <tt>read_attribute</tt> method).
+ # (Alias for the protected <tt>read_attribute</tt> method). It raises an <tt>ActiveModel::MissingAttributeError</tt>
+ # error if the identified attribute is missing.
#
# class Person < ActiveRecord::Base
+ # belongs_to :organization
# end
#
# person = Person.new(name: 'Francesco', age: '22'
# person[:name] # => "Francesco"
# person[:age] # => 22
+ #
+ # person = Person.select('id').first
+ # person[:name] # => ActiveModel::MissingAttributeError: missing attribute: name
+ # person[:organization_id] # => ActiveModel::MissingAttributeError: missing attribute: organization_id
def [](attr_name)
- read_attribute(attr_name)
+ read_attribute(attr_name) { |n| missing_attribute(n, caller) }
end
# Updates the attribute identified by <tt>attr_name</tt> with the specified +value+.
@@ -287,6 +287,12 @@ def test_read_attribute
assert_equal "Don't change the topic", topic[:title]
end
+ def test_read_attribute_raises_missing_attribute_error_when_not_exists
+ computer = Computer.select('id').first
+ assert_raises(ActiveModel::MissingAttributeError) { computer[:developer] }
+ assert_raises(ActiveModel::MissingAttributeError) { computer[:extendedWarranty] }
+ end
+
def test_read_attribute_when_false
topic = topics(:first)
topic.approved = false

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