New in Symfony 7.3 Yaml Improvements

Dumping Quoted Strings

Contributed by Dalibor Karlović in #59880

When dumping string contents, they are only quoted by default when they contain unsafe values (e.g. white spaces). Otherwise, they are dumped unquoted because that is more compact and still valid YAML:

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use Symfony\Component\Yaml\Yaml;

$data = ['data' => ['OTEL_EXPORTER_OTLP_PROTOCOL' => 'grpc']];
$yaml = Yaml::dump($data);

This code outputs:

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data:
    OTEL_EXPORTER_OTLP_PROTOCOL: grpc

This is technically valid YAML, but some strict parsers will warn you about any unquoted string contents (e.g. when dumping ConfigMap entries in Kubernetes). That's why Symfony 7.3 added a new flag to make this behavior configurable:

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$yaml = Yaml::dump($data, 2, 4, Yaml::DUMP_FORCE_DOUBLE_QUOTES_ON_VALUES);

This code now outputs:

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data:
    OTEL_EXPORTER_OTLP_PROTOCOL: "grpc"

Dumping Compact Collections of Maps

Contributed by gr8b in #59315

Consider the following data structure representing a list of associative arrays in PHP:

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$data = ['planets' => [
    ['name' => 'Mercury', 'distance' => 57910000],
    ['name' => 'Jupiter', 'distance' => 778500000],
];

When dumping this data as YAML, the result is:

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planets:
  -
    name: Mercury
    distance: 57910000
  -
    name: Jupiter
    distance: 778500000

In Symfony 7.3, a new flag was added to configure this behavior and allow you to generate more compact dumps:

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$yaml = Yaml::dump($data, 2, 4, Yaml::DUMP_COMPACT_NESTED_MAPPING);

This code now outputs:

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planets:
  - name: Mercury
    distance: 57910000
  - name: Jupiter
    distance: 778500000

Dumping Empty Entries

Contributed by Alexandre Daubois in #58243

Consider the following code that dumps YAML data for a Docker Compose volumes section:

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$data = ['volumes' => ['db-data' => null]];
$yaml = Yaml::dump($data);

This code outputs:

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volumes:
    db-data: null

If you use an empty string instead of null as the value of db-data, you'll get this:

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volumes:
    db-data: ''

There is no way to dump this YAML entry as an empty entry without any content (neither null nor an empty string). That's why Symfony 7.3 introduced a new flag to dump empty entries:

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$data = ['volumes' => ['db-data' => null]];
$yaml = Yaml::dump($data, 2, 4, Yaml::DUMP_NULL_AS_EMPTY);

This code now outputs:

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volumes:
    db-data: