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prefer-date-format

added in: 1.7.0
warning
⚙️🛠
Pro+

Warns when DateTime, values are formatted with toString instead of DateFormat.format().

⚙️ Config​

Set ignored-invocations (default is empty) to ignore toString calls inside a specific invocation (example).

analysis_options.yaml
dart_code_metrics:
  rules:
    - prefer-date-format:
        ignored-invocations:
           - print

Example​

❌ Bad:

void main() {
  final DateTime dateTimeValue = DateTime.now();

  // LINT: Prefer using 'DateFormat()' to convert a date to a string value.
  final dateTimeString = dateTimeValue.toString();

  // LINT: Prefer using 'DateFormat()' to convert a date to a string value.
  final dateTimeString = '$dateTimeValue';
}

✅ Good:

void main() {
  final DateTime dateTimeValue = DateTime.now();

  final dateTimeString = DateFormat().format(dateTimeValue);
  final dateTimeString = '${DateFormat().format(dateTimeValue)}';
}

Example with "ignored-invocations"​

Config
analysis_options.yaml
dart_code_metrics:
  rules:
    - prefer-date-format:
        ignored-invocations:
           - print

✅ Good:

void main() {
  final DateTime dateTimeValue = DateTime.now();

  print(dateTimeValue); // Correct, ignored
}