UPGRADE FROM 3.0 to 3.1
=======================

DependencyInjection
-------------------

 * Using unsupported configuration keys in YAML configuration files has been
   deprecated and will raise an exception in Symfony 4.0.

 * Using unsupported options to configure service aliases has been deprecated
   and will raise an exception in Symfony 4.0.

Form
----

 * The `choices_as_values` option of the `ChoiceType` has been deprecated and
   will be removed in Symfony 4.0.

 * Support for data objects that implements both `Traversable` and `ArrayAccess`
   in `ResizeFormListener::preSubmit` method has been deprecated and will be
   removed in Symfony 4.0.
 * `TextType` now implements `DataTransformerInterface` and will always return
   an empty string when `empty_data` option is explicitly assigned to it.

 * Using callable strings as choice options in ChoiceType has been deprecated
   in favor of `PropertyPath` in Symfony 4.0 use a "\Closure" instead.

   Before:

   ```php
   'choice_value' => new PropertyPath('range'),
   'choice_label' => 'strtoupper',
   ```

   After:

   ```php
   'choice_value' => 'range',
   'choice_label' => function ($choice) {
       return strtoupper($choice);
   },
   ```

 * Caching of the loaded `ChoiceListInterface` in the `LazyChoiceList` has been deprecated,
   it must be cached in the `ChoiceLoaderInterface` implementation instead.

FrameworkBundle
---------------

 * As it was never an officially supported feature, the support for absolute
   template paths has been deprecated and will be removed in Symfony 4.0.

 * The abstract `Controller` class now has a `json()` helper method that creates
   a `JsonResponse`. If you have existing controllers extending `Controller`
   that contain a method with this name, you need to rename that method to avoid
   conflicts.

 * The following form types registered as services have been deprecated and
   will be removed in Symfony 4.0; use their fully-qualified class name instead:

    - `"form.type.birthday"`
    - `"form.type.checkbox"`
    - `"form.type.collection"`
    - `"form.type.country"`
    - `"form.type.currency"`
    - `"form.type.date"`
    - `"form.type.datetime"`
    - `"form.type.email"`
    - `"form.type.file"`
    - `"form.type.hidden"`
    - `"form.type.integer"`
    - `"form.type.language"`
    - `"form.type.locale"`
    - `"form.type.money"`
    - `"form.type.number"`
    - `"form.type.password"`
    - `"form.type.percent"`
    - `"form.type.radio"`
    - `"form.type.range"`
    - `"form.type.repeated"`
    - `"form.type.search"`
    - `"form.type.textarea"`
    - `"form.type.text"`
    - `"form.type.time"`
    - `"form.type.timezone"`
    - `"form.type.url"`
    - `"form.type.button"`
    - `"form.type.submit"`
    - `"form.type.reset"`

 * The `framework.serializer.cache` option and the service
   `serializer.mapping.cache.apc` have been deprecated. APCu should now be
   automatically used when available.

HttpKernel
----------

 * Passing objects as URI attributes to the ESI and SSI renderers has been
   deprecated and will be removed in Symfony 4.0. The inline fragment
   renderer should be used with object attributes.

 * The `ControllerResolver::getArguments()` method has been deprecated and will
   be removed in 4.0. If you have your own `ControllerResolverInterface`
   implementation, you should inject either an `ArgumentResolverInterface`
   instance or the new `ArgumentResolver` in the `HttpKernel`.

Serializer
----------

 * Passing a Doctrine `Cache` instance to the `ClassMetadataFactory` has been
   deprecated and will not be supported in Symfony 4.0. You should use the
   `CacheClassMetadataFactory` class instead.

Translation
-----------

 * Deprecated the backup feature of the file dumper classes. It will be removed
   in Symfony 4.0.

Yaml
----

 * Usage of `%` at the beginning of an unquoted string has been deprecated and
   will lead to a `ParseException` in Symfony 4.0.

 * The `Dumper::setIndentation()` method is deprecated and will be removed in
   Symfony 4.0. Pass the indentation level to the constructor instead.

 * Deprecated support for passing `true`/`false` as the second argument to the
   `parse()` method to trigger exceptions when an invalid type was passed.

   Before:

   ```php
   Yaml::parse('{ "foo": "bar", "fiz": "cat" }', true);
   ```

   After:

   ```php
   Yaml::parse('{ "foo": "bar", "fiz": "cat" }', Yaml::PARSE_EXCEPTION_ON_INVALID_TYPE);
   ```

 * Deprecated support for passing `true`/`false` as the third argument to the
   `parse()` method to toggle object support.

   Before:

   ```php
   Yaml::parse('{ "foo": "bar", "fiz": "cat" }', false, true);
   ```

   After:

   ```php
   Yaml::parse('{ "foo": "bar", "fiz": "cat" }', Yaml::PARSE_OBJECT);
   ```

 * Deprecated support for passing `true`/`false` as the fourth argument to the
   `parse()` method to parse objects as maps.

   Before:

   ```php
   Yaml::parse('{ "foo": "bar", "fiz": "cat" }', false, false, true);
   ```

   After:

   ```php
   Yaml::parse('{ "foo": "bar", "fiz": "cat" }', Yaml::PARSE_OBJECT_FOR_MAP);
   ```

 * Deprecated support for passing `true`/`false` as the fourth argument to the
   `dump()` method to trigger exceptions when an invalid type was passed.

   Before:

   ```php
   Yaml::dump(array('foo' => new A(), 'bar' => 1), 0, 0, true);
   ```

   After:

   ```php
   Yaml::dump(array('foo' => new A(), 'bar' => 1), 0, 0, Yaml::DUMP_EXCEPTION_ON_INVALID_TYPE);
   ```

 * Deprecated support for passing `true`/`false` as the fifth argument to the
   `dump()` method to toggle object support.

   Before:

   ```php
   Yaml::dump(array('foo' => new A(), 'bar' => 1), 0, 0, false, true);
   ```

   After:

   ```php
   Yaml::dump(array('foo' => new A(), 'bar' => 1), 0, 0, Yaml::DUMP_OBJECT);
   ```

 * The `!!php/object` tag to indicate dumped PHP objects has been deprecated
   and will be removed in Symfony 4.0. Use the `!php/object` tag instead.

Validator
---------

 * The `DateTimeValidator::PATTERN` constant has been deprecated and will be
   removed in Symfony 4.0.
