Fast

One of the goal of Symfony YAML is to find the right balance between speed and features. It supports just the needed feature to handle configuration files.

Real Parser

It sports a real parser and is able to parse a large subset of the YAML specification, for all your configuration needs. It also means that the parser is pretty robust, easy to understand, and simple enough to extend.

Clear error messages

Whenever you have a syntax problem with your YAML files, the library outputs a helpful message with the filename and the line number where the problem occurred. It eases the debugging a lot.

Dump support

It is also able to dump PHP arrays to YAML with object support, and inline level configuration for pretty outputs.

Types Support

It supports most of the YAML built-in types like dates, integers, octals, booleans, and much more...

Full merge key support

Full support for references, aliases, and full merge key. Don't repeat yourself by referencing common configuration bits.

Reading YAML Files

The parse() method parses a YAML string and converts it to a PHP array:

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use Symfony\Component\Yaml\Parser;

$yaml = new Parser();

$value = $yaml->parse(file_get_contents('/path/to/file.yml'));

If an error occurs during parsing, the parser throws a ParseException exception indicating the error type and the line in the original YAML string where the error occurred:

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use Symfony\Component\Yaml\Exception\ParseException;

try {
    $value = $yaml->parse(file_get_contents('/path/to/file.yml'));
} catch (ParseException $e) {
    printf("Unable to parse the YAML string: %s", $e->getMessage());
}

When loading a YAML file, it is sometimes better to use the parse() wrapper method:

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use Symfony\Component\Yaml\Yaml;

$yaml = Yaml::parse('/path/to/file.yml');

The parse() static method takes a YAML string or a file containing YAML. Internally, it calls the parse() method, but enhances the error if something goes wrong by adding the filename to the message.

Executing PHP Inside YAML Files

By default, if you include PHP inside a YAML file, it will not be parsed. If you do want PHP to be parsed, you must call Yaml::enablePhpParsing() before parsing the file to activate this mode. If you only want to allow PHP code for a single YAML file, be sure to disable PHP parsing after parsing the single file by calling Yaml::$enablePhpParsing = false; ($enablePhpParsing is a public property).

Writing YAML Files

The dump() method dumps any PHP array to its YAML representation:

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use Symfony\Component\Yaml\Dumper;

$array = array(
    'foo' => 'bar',
    'bar' => array('foo' => 'bar', 'bar' => 'baz'),
);

$dumper = new Dumper();

$yaml = $dumper->dump($array);

file_put_contents('/path/to/file.yml', $yaml);

If an error occurs during the dump, the parser throws a DumpException exception.

If you only need to dump one array, you can use the dump() static method shortcut:

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use Symfony\Component\Yaml\Yaml;

$yaml = Yaml::dump($array, $inline);

The YAML format supports two kind of representation for arrays, the expanded one, and the inline one. By default, the dumper uses the inline representation:

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{ foo: bar, bar: { foo: bar, bar: baz } }

The second argument of the dump() method customizes the level at which the output switches from the expanded representation to the inline one:

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echo $dumper->dump($array, 1);

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foo: bar
bar: { foo: bar, bar: baz }

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echo $dumper->dump($array, 2);

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foo: bar
bar:
    foo: bar
    bar: baz