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PATCH is (also) for Updating (basically)

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The main HTTP methods are: GET, POST, PUT and DELETE. There's another one you hear a lot about: PATCH.

The simple, but not entirely accurate definition of PATCH is this: it's just like PUT, except you don't need to send up the entire resource body. If you just want to update tagLine, just send that field.

So really, PATCH is a bit nicer to work with than PUT, and we'll support both. Start with the test - public function testPATCHProgrammer():

... lines 1 - 93
public function testPATCHProgrammer()
... lines 96 - 111
... lines 113 - 125

Copy the inside of the PUT test: they'll be almost identical.

If you follow the rules with PUT, then if you don't send tagLine, the server should nullify it. Symfony's form system works like that, so our PUT is acting right. Good PUT!

But for PATCH, let's only send tagLine with a value of bar. When we do this, we expect tagLine to be bar, but we also expect avatarNumber is still equal to 5. We're not sending avatarNumber, which means: don't change it. And change the method from put() to patch():

... lines 1 - 93
public function testPATCHProgrammer()
'nickname' => 'CowboyCoder',
'avatarNumber' => 5,
'tagLine' => 'foo',
$data = array(
'tagLine' => 'bar',
$response = $this->client->patch('/api/programmers/CowboyCoder', [
'body' => json_encode($data)
$this->assertEquals(200, $response->getStatusCode());
$this->asserter()->assertResponsePropertyEquals($response, 'avatarNumber', 5);
$this->asserter()->assertResponsePropertyEquals($response, 'tagLine', 'bar');
... lines 112 - 124

In reality, PATCH can be more complex than this, and we talk about that in our other REST screencast (see The Truth Behind PATCH). But most API's make PATCH work like this.

Make sure the test fails - filter it for PATCH to run just this one:

phpunit -c app --filter PATCH

Sweet! 405, method not allowed. Time to fix that!

Support PUT and PATCH

Since PUT and PATCH are so similar, we can handle them in the same action. Just change the @Method annotation to have a curly-brace with PUT and PATCH inside of it:

... lines 1 - 87
* @Route("/api/programmers/{nickname}")
* @Method({"PUT", "PATCH"})
public function updateAction($nickname, Request $request)
... lines 93 - 158

Now, this route accepts PUT or PATCH. Try the test again:

phpunit -c app --filter PATCH

Woh, 500 error! Integrity constraint: avatarNumber cannot be null. It is hitting our endpoint and because we're not sending avatarNumber, the form framework is nullifying it, which eventually makes the database yell at us.

The work of passing the data to the form is done in our private processForm() method. And when it calls $form->submit(), there's a second argument called $clearMissing. It's default value - true - means that any missing fields are nullified. But if you set it to false, those fields are ignored. That's perfect PATCH behavior. Create a new variable above this line called $clearMissing and set it to $request->getMethod() != 'PATCH':

... lines 1 - 139
private function processForm(Request $request, FormInterface $form)
$data = json_decode($request->getContent(), true);
$clearMissing = $request->getMethod() != 'PATCH';
... line 145
... lines 147 - 158

In other words, clear all the missing fields, unless the request method is PATCH. Pass this as the second argument:

... lines 1 - 139
private function processForm(Request $request, FormInterface $form)
$data = json_decode($request->getContent(), true);
$clearMissing = $request->getMethod() != 'PATCH';
$form->submit($data, $clearMissing);
... lines 147 - 158

Head back, get rid of the big error message and run things again:

phpunit -c app --filter PATCH

Boom! We've got PUT and PATCH support with about 2 lines of code.

Leave a comment!

This tutorial uses an older version of Symfony. The concepts of REST are still valid, but I recommend using API Platform in new Symfony apps.

What PHP libraries does this tutorial use?

// composer.json
    "require": {
        "php": ">=5.3.3",
        "symfony/symfony": "2.6.*", // v2.6.11
        "doctrine/orm": "~2.2,>=2.2.3,<2.5", // v2.4.7
        "doctrine/dbal": "<2.5", // v2.4.4
        "doctrine/doctrine-bundle": "~1.2", // v1.4.0
        "twig/extensions": "~1.0", // v1.2.0
        "symfony/assetic-bundle": "~2.3", // v2.6.1
        "symfony/swiftmailer-bundle": "~2.3", // v2.3.8
        "symfony/monolog-bundle": "~2.4", // v2.7.1
        "sensio/distribution-bundle": "~3.0,>=3.0.12", // v3.0.21
        "sensio/framework-extra-bundle": "~3.0,>=3.0.2", // v3.0.7
        "incenteev/composer-parameter-handler": "~2.0", // v2.1.0
        "hautelook/alice-bundle": "0.2.*", // 0.2
        "jms/serializer-bundle": "0.13.*" // 0.13.0
    "require-dev": {
        "sensio/generator-bundle": "~2.3", // v2.5.3
        "behat/behat": "~3.0", // v3.0.15
        "behat/mink-extension": "~2.0.1", // v2.0.1
        "behat/mink-goutte-driver": "~1.1.0", // v1.1.0
        "behat/mink-selenium2-driver": "~1.2.0", // v1.2.0
        "phpunit/phpunit": "~4.6.0" // 4.6.4