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Description:

checked yaml

package:checked_yaml provides a checkedYamlDecode function that wraps the
the creation of classes annotated for package:json_serializable it helps
provide more helpful exceptions when the provided YAML is not compatible with
the target type.
package:json_serializable can generate classes that can parse the
YamlMap type provided by package:yaml when anyMap: true is specified
for the class annotation.
@JsonSerializable(
anyMap: true,
checked: true,
disallowUnrecognizedKeys: true,
)
class Configuration {
@JsonKey(required: true)
final String name;
final int count;

Configuration({required this.name, required this.count}) {
if (name.isEmpty) {
throw ArgumentError.value(name, 'name', 'Cannot be empty.');
}
}

factory Configuration.fromJson(Map json) => _$ConfigurationFromJson(json);

Map<String, dynamic> toJson() => _$ConfigurationToJson(this);

@override
String toString() => 'Configuration: ${toJson()}';
}
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When checked: true is set, exceptions thrown when decoding an instance from a
Map are wrapped in a CheckedFromJsonException. The
checkedYamlDecode function catches these exceptions and throws a
ParsedYamlException which maps the exception to the location in the input
YAML with the error.
void main(List<String> arguments) {
final sourcePathOrYaml = arguments.single;
String yamlContent;
Uri? sourceUri;

if (FileSystemEntity.isFileSync(sourcePathOrYaml)) {
yamlContent = File(sourcePathOrYaml).readAsStringSync();
sourceUri = Uri.parse(sourcePathOrYaml);
} else {
yamlContent = sourcePathOrYaml;
}

final config = checkedYamlDecode(
yamlContent,
(m) => Configuration.fromJson(m!),
sourceUrl: sourceUri,
);
print(config);
}
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When parsing an invalid YAML file, an actionable error message is produced.
$ dart example/example.dart '{"name": "", "count": 1}'
Unhandled exception:
ParsedYamlException: line 1, column 10: Unsupported value for "name". Cannot be empty.
╷
1 │ {"name": "", "count": 1}
│ ^^
╵
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