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avoid-not-encodable-in-to-json

added in: 1.14.0
warning
⚙️
preset: recommended

Warns when a toJson method references a non-encodable object.

Passing results of such toJson methods to jsonEncode will result in a runtime exception.

⚙️ Config​

Set methods (default is empty) to configure a list of additional methods that should be checked.

dart_code_metrics:
  ...
  rules:
    ...
    - avoid-not-encodable-in-to-json:
        methods:
          - customToJson

Example​

❌ Bad:

class SomeClass {
  final String value;

  const SomeClass(this.value);
}

class WithJson {
  Map<String, Object?> toJson(Set<String> values) => {
    'key': values, // LINT
    'function': () => null, // LINT
    'instance': SomeClass(''), // LINT
  };
}

✅ Good:

class SomeClass {
  final String value;

  const SomeClass(this.value);

  Map<String, Object?> toJson() => {'some': 'class'};
}

class WithJson {
  Map<String, Object?> toJson(Set<String> values) => {
    'key': values.toList(),
    'instance': SomeClass(''),
  };
}