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rails--rails/activerecord/test/fixtures
Godfrey Chan 2d73f5ae2f Fixed serialization for records with an attribute named format.
* * *

This bug can be triggered when serializing record R (the instance) of type C
(the class), provided that the following conditions are met:

1. The name of one or more columns/attributes on C/R matches an existing private
   method on C (e.g. those defined by `Kernel`, such as `format`).

2. The attribute methods have not yet been generated on C.

In this case, the matching private methods will be called by the serialization
code (with no arguments) and their return values will be serialized instead. If
the method requires one or more arguments, it will result in an `ArgumentError`.

This regression is introduced in d1316bb.

* * *

Attribute methods (e.g. `#name` and `#format`, assuming the class has columns
named `name` and `format` in its database table) are lazily defined. Instead of
defining them when a the class is defined (e.g. in the `inherited` hook on
`ActiveRecord::Base`), this operation is deferred until they are first accessed.

The reason behind this is that is defining those methods requires knowing what
columns are defined on the database table, which usually requires a round-trip
to the database. Deferring their definition until the last-possible moment helps
reducing unnessary work, especially in development mode where classes are
redefined and throw away between requests.

Typically, when an attribute is first accessed (e.g. `a_book.format`), it will
fire the `method_missing` hook on the class, which triggers the definition of
the attribute methods. This even works for methods like `format`, because
calling a private method with an explicit receiver will also trigger that hook.

Unfortunately, `read_attribute_for_serialization` is simply an alias to `send`,
which does not respect method visibility. As a result, when serializing a record
with those conflicting attributes, the `method_missing` is not fired, and as a
result the attribute methods are not defined one would expected.

Before d1316bb, this is negated by the fact that calling the `run_callbacks`
method will also trigger a call to `respond_to?`, which is another trigger point
for the class to define its attribute methods. Therefore, when Active Record
tries to run the `after_find` callbacks, it will also define all the attribute
methods thus masking the problem.

* * *

The proper fix for this problem is probably to restrict `read_attribute_for_serialization`
to call public methods only (i.e. alias `read_attribute_for_serialization` to
`public_send` instead of `send`). This however would be quite risky to change
in a patch release and would probably require a full deprecation cycle.

Another approach would be to override `read_attribute_for_serialization` inside
Active Record to force the definition of attribute methods:

   def read_attribute_for_serialization(attribute)
     self.class.define_attribute_methods
     send(attribute)
   end

Unfortunately, this is quite likely going to cause a performance degradation.

This patch therefore restores the behaviour from the 4-0-stable branch by
explicitly forcing the class to define its attribute methods in a similar spot
(when records are initialized). This should not cause any extra roundtrips to
the database because the `@columns` should already be cached on the class.

Fixes #15188.
2014-05-22 14:35:04 -07:00
..
admin
all load fixtures from linked folders 2013-08-05 16:35:49 -03:00
categories
naked
reserved_words Improve the derivation of HABTM assocation join table names 2012-06-22 06:27:11 +01:00
to_be_linked load fixtures from linked folders 2013-08-05 16:35:49 -03:00
.gitignore
accounts.yml
author_addresses.yml
author_favorites.yml
authors.yml
binaries.yml
books.yml Fixed serialization for records with an attribute named format. 2014-05-22 14:35:04 -07:00
cars.yml
categories.yml
categories_ordered.yml
categories_posts.yml
categorizations.yml
clubs.yml
collections.yml
colleges.yml
comments.yml
companies.yml Ensure AR #second, #third, etc. finders work through associations 2014-01-21 19:35:27 -05:00
computers.yml Fixed STI classes not defining an attribute method if there is a 2014-02-23 11:00:55 -08:00
courses.yml
customers.yml
dashboards.yml
developers.yml
developers_projects.yml
dog_lovers.yml Update other counter caches on destroy 2013-03-20 13:43:07 -07:00
dogs.yml Update other counter caches on destroy 2013-03-20 13:43:07 -07:00
edges.yml
entrants.yml
essays.yml
faces.yml
fk_test_has_fk.yml
fk_test_has_pk.yml
friendships.yml Refactor Person/Friendship relationships to be more intuitive 2013-03-17 02:11:19 -04:00
funny_jokes.yml
interests.yml
items.yml
jobs.yml
legacy_things.yml
mateys.yml Rename "Fixtures" class to "FixtureSet" 2012-10-07 19:15:58 +02:00
member_details.yml
member_types.yml
members.yml
memberships.yml
men.yml
minimalistics.yml
minivans.yml
mixed_case_monkeys.yml
mixins.yml
movies.yml
organizations.yml
other_topics.yml
owners.yml Extend ActiveRecord::Base#cache_key to take an optional list of timestamp attributes of which the highest will be used. 2013-11-02 16:05:19 -07:00
parrots.yml
parrots_pirates.yml Rename "Fixtures" class to "FixtureSet" 2012-10-07 19:15:58 +02:00
people.yml Refactor Person/Friendship relationships to be more intuitive 2013-03-17 02:11:19 -04:00
peoples_treasures.yml Rename "Fixtures" class to "FixtureSet" 2012-10-07 19:15:58 +02:00
pets.yml has_many through obeys order on through association 2013-04-04 15:45:13 -04:00
pirates.yml Extend fixture label replacement to allow string interpolation 2014-03-15 22:11:36 -04:00
posts.yml
price_estimates.yml
products.yml
projects.yml
randomly_named_a9.yml
ratings.yml Revert "Merge pull request #14544 from jefflai2/named_scope_sti" 2014-05-21 12:15:57 -03:00
readers.yml Prevent Relation#merge from collapsing wheres on the RHS 2013-01-27 20:34:52 +00:00
references.yml
ships.yml
speedometers.yml
sponsors.yml we should have unique sponsorable ids in the fixtures at least 2013-10-14 15:27:49 -07:00
string_key_objects.yml
subscribers.yml
subscriptions.yml
taggings.yml
tags.yml
tasks.yml Fix broken link to Fixtures documentation on guides 2013-08-29 15:44:12 -05:00
teapots.yml
topics.yml Ensure #second acts like #first AR finder 2014-01-20 16:58:18 -05:00
toys.yml has_many through obeys order on through association 2013-04-04 15:45:13 -04:00
traffic_lights.yml test case for serialize default values. 2013-03-07 17:26:35 +01:00
treasures.yml
uuid_children.yml Auto-generate stable fixture UUIDs on PostgreSQL. 2014-01-07 19:05:50 +01:00
uuid_parents.yml Auto-generate stable fixture UUIDs on PostgreSQL. 2014-01-07 19:05:50 +01:00
variants.yml
vegetables.yml rewrite inheritance tests with a custom inheritance_column 2012-09-03 20:30:43 +02:00
vertices.yml
warehouse-things.yml
zines.yml