Justin Hileman
e0ec0d0e18
spyc has a parsing bug which causes partials to fail. I mean, they fail for other reasons too. And we're getting to those. But we don't need to debug YAML parsers while we're at it.
111 lines
2.9 KiB
Markdown
111 lines
2.9 KiB
Markdown
Using Symfony YAML
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==================
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The Symfony YAML library is very simple and consists of two main classes: one
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to parse YAML strings (`sfYamlParser`), and the other to dump a PHP array to
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a YAML string (`sfYamlDumper`).
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On top of these two core classes, the main `sfYaml` class acts as a thin
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wrapper and simplifies common uses.
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Reading YAML Files
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------------------
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The `sfYamlParser::parse()` method parses a YAML string and converts it to a
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PHP array:
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[php]
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$yaml = new sfYamlParser();
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$value = $yaml->parse(file_get_contents('/path/to/file.yaml'));
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If an error occurs during parsing, the parser throws an exception indicating
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the error type and the line in the original YAML string where the error
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occurred:
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[php]
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try
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{
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$value = $yaml->parse(file_get_contents('/path/to/file.yaml'));
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}
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catch (InvalidArgumentException $e)
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{
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// an error occurred during parsing
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echo "Unable to parse the YAML string: ".$e->getMessage();
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}
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>**TIP**
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>As the parser is reentrant, you can use the same parser object to load
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>different YAML strings.
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When loading a YAML file, it is sometimes better to use the `sfYaml::load()`
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wrapper method:
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[php]
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$loader = sfYaml::load('/path/to/file.yml');
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The `sfYaml::load()` static method takes a YAML string or a file containing
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YAML. Internally, it calls the `sfYamlParser::parse()` method, but with some
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added bonuses:
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* It executes the YAML file as if it was a PHP file, so that you can embed
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PHP commands in YAML files;
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* When a file cannot be parsed, it automatically adds the file name to the
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error message, simplifying debugging when your application is loading
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several YAML files.
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Writing YAML Files
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------------------
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The `sfYamlDumper` dumps any PHP array to its YAML representation:
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[php]
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$array = array('foo' => 'bar', 'bar' => array('foo' => 'bar', 'bar' => 'baz'));
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$dumper = new sfYamlDumper();
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$yaml = $dumper->dump($array);
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file_put_contents('/path/to/file.yaml', $yaml);
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>**NOTE**
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>Of course, the Symfony YAML dumper is not able to dump resources. Also,
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>even if the dumper is able to dump PHP objects, it is to be considered
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>an alpha feature.
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If you only need to dump one array, you can use the `sfYaml::dump()` static
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method shortcut:
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[php]
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$yaml = sfYaml::dump($array, $inline);
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The YAML format supports two kind of representation for arrays, the expanded
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one, and the inline one. By default, the dumper uses the inline
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representation:
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[yml]
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{ foo: bar, bar: { foo: bar, bar: baz } }
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The second argument of the `dump()` method customizes the level at which the
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output switches from the expanded representation to the inline one:
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[php]
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echo $dumper->dump($array, 1);
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-
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[yml]
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foo: bar
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bar: { foo: bar, bar: baz }
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-
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[php]
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echo $dumper->dump($array, 2);
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-
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[yml]
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foo: bar
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bar:
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foo: bar
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bar: baz
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