# Upgrade Guide

# API Platform 3.4

Remove the keep_legacy_inflector, the event_listeners_backward_compatibility_layer and the rfc_7807_compliant_errors flag:

api_platform:
-        event_listeners_backward_compatibility_layer: false
-        keep_legacy_inflector: false
        extra_properties:
            standard_put: true
-            rfc_7807_compliant_errors: true

If you use a custom normalizer for validation exception use:

api_platform:
	validator:
		legacy_validation_exception: true

Indeed, we will throw another validation class in API Platform 4 we will throw ApiPlatform\Validator\Exception\ValidationException instead of ApiPlatform\Symfony\Validator\Exception\ValidationException

It’s really important to add the use_symfony_listeners flag, set to true if you use Symfony listeners or controllers:

api_platform:
	use_symfony_listeners: false

The keep_legacy_inflector flag will be removed from API Platform 4, you need to fix your issues first. In API Platform 3.4, the Inflector is available as a service that you can configure through:

api_platform:
    inflector: api_platform.metadata.inflector

Implement the ApiPlatform\Metadata\InflectorInterface if you need to tweak its behavior.

We added an hydra_prefix configuration as the hydra: prefix will be removed by default in API Platform 4:

api_platform:
    serializer:
        hydra_prefix: false

# API Platform 3.1/3.2

This is the recommended configuration for API Platform 3.2. We review each of these changes in this document.

api_platform:
    title: Hello API Platform
    version: 1.0.0
    formats:
        jsonld: ['application/ld+json']
    docs_formats:
        jsonld: ['application/ld+json']
        jsonopenapi: ['application/vnd.openapi+json']
        html: ['text/html']
    defaults:
        stateless: true
        cache_headers:
            vary: ['Content-Type', 'Authorization', 'Origin']
        extra_properties:
            standard_put: true
            rfc_7807_compliant_errors: true
    event_listeners_backward_compatibility_layer: false
    keep_legacy_inflector: false

# Formats

We noticed that API Platform was enabling json by default because of our OpenAPI support. We introduced the new application/vnd.openapi+json. Therefore if you want json you need to explicitly handle it:

formats: 
    json: ['application/json']

You can also remove documentations you’re not using via the new docs_formats.

A new option error_formats is also used for content negotiation.

# Event listeners

For new users we recommend to use

event_listeners_backward_compatibility_layer: false

This allows API Platform to not use http kernel event listeners. It also allows you to force options like read: true or validate: true. This simplifies use cases like validating a delete operation Event listeners will not get removed and are not deprecated, they’ll use our providers and processors in a future version.

# Inflector

We’re switching to symfony/string inflector, to keep using doctrine/inflector use:

keep_legacy_inflector: true

We strongly recommend that you use your own inflector anyways with a PathSegmentNameGenerator.

# Errors

defaults:
    extra_properties:
        rfc_7807_compliant_errors: true

As this is an extraProperties it’s configurable per resource/operation. This is improving the compatibility of Hydra errors with JSON problem. It also enables new extension points on Errors such as Error provider and Error Resource.