feature #30504 [DI] replace "nullable" env processor by improving the "default" one (nicolas-grekas)

This PR was merged into the 4.3-dev branch.

Discussion
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[DI] replace "nullable" env processor by improving the "default" one

| Q             | A
| ------------- | ---
| Branch?       | master
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

Neither `nullable` nor `default` are released yet.
I propose to replace the `nullable` processor (see #29767) with an improved `default` one (from #28976).
`%env(default::FOO)%` now defaults to `null` when the env var doesn't exist or compares to false".

ping @jderusse @bpolaszek

Commits
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c50aad2be1 [DI] replace "nullable" env processor by improving the "default" one

src/Symfony/Component/DependencyInjection/CHANGELOG.md

@@ -5,8 +5,7 @@ CHANGELOG
 -----
 
  * added `%env(trim:...)%` processor to trim a string value
- * added `%env(default:...)%` processor to fallback to a default value
- * added `%env(nullable:...)%` processor to allow empty variables to be processed as null values
+ * added `%env(default:param_name:...)%` processor to fallback to a parameter or to null when using `%env(default::...)%`
  * added support for deprecating aliases
  * made `ContainerParametersResource` final and not implement `Serializable` anymore
  * added ability to define an index for a tagged collection

src/Symfony/Component/DependencyInjection/EnvVarProcessor.php

@@ -41,7 +41,6 @@ class EnvVarProcessor implements EnvVarProcessorInterface
             'int' => 'int',
             'json' => 'array',
             'key' => 'bool|int|float|string|array',
-            'nullable' => 'bool|int|float|string|array',
             'resolve' => 'string',
             'default' => 'bool|int|float|string|array',
             'string' => 'string',
@@ -84,15 +83,21 @@ class EnvVarProcessor implements EnvVarProcessorInterface
             $next = substr($name, $i + 1);
             $default = substr($name, 0, $i);
 
-            if (!$this->container->hasParameter($default)) {
+            if ('' !== $default && !$this->container->hasParameter($default)) {
                 throw new RuntimeException(sprintf('Invalid env fallback in "default:%s": parameter "%s" not found.', $name, $default));
             }
 
             try {
-                return $getEnv($next);
+                $env = $getEnv($next);
+
+                if ('' !== $env && null !== $env) {
+                    return $env;
+                }
             } catch (EnvNotFoundException $e) {
-                return $this->container->getParameter($default);
+                // no-op
             }
+
+            return '' === $default ? null : $this->container->getParameter($default);
         }
 
         if ('file' === $prefix) {
@@ -196,10 +201,6 @@ class EnvVarProcessor implements EnvVarProcessorInterface
             return str_getcsv($env);
         }
 
-        if ('nullable' === $prefix) {
-            return '' === $env ? null : $env;
-        }
-
         if ('trim' === $prefix) {
             return trim($env);
         }

src/Symfony/Component/DependencyInjection/Tests/Compiler/RegisterEnvVarProcessorsPassTest.php

@@ -39,7 +39,6 @@ class RegisterEnvVarProcessorsPassTest extends TestCase
             'int' => ['int'],
             'json' => ['array'],
             'key' => ['bool', 'int', 'float', 'string', 'array'],
-            'nullable' => ['bool', 'int', 'float', 'string', 'array'],
             'resolve' => ['string'],
             'default' => ['bool', 'int', 'float', 'string', 'array'],
             'string' => ['string'],

src/Symfony/Component/DependencyInjection/Tests/EnvVarProcessorTest.php

@@ -440,7 +440,7 @@ class EnvVarProcessorTest extends TestCase
     public function testGetEnvNullable($value, $processed)
     {
         $processor = new EnvVarProcessor(new Container());
-        $result = $processor->getEnv('nullable', 'foo', function ($name) use ($value) {
+        $result = $processor->getEnv('default', ':foo', function ($name) use ($value) {
             $this->assertSame('foo', $name);
 
             return $value;