prefer_enums_by_name

v0.4.0 Warning Fix Collection & Type

Using .firstWhere((e) => e.name == value) on enum values can be replaced with the built-in .byName() method, available since Dart 2.15. The dedicated method is more concise, more readable, and throws a clear ArgumentError when the name is not found.

Why use this rule

.byName() was specifically designed for looking up enum values by their string name. It is shorter, self-documenting, and provides a better error message on failure compared to the firstWhere approach which throws a generic StateError.

See also: Dart enums

Don’t

enum Style { standard, express, overnight }

void example() {
  // Use .byName() instead of .firstWhere()
  final style = Style.values.firstWhere(
    (speed) => speed.name == 'express',
  );

  // Reversed comparison also detected
  final style2 = Style.values.firstWhere(
    (speed) => 'overnight' == speed.name,
  );

  // Variable comparison
  final name = 'underline';
  final style3 = Style.values.firstWhere((speed) => speed.name == name);
}

Do

enum Style { standard, express, overnight }

void example() {
  final style = Style.values.byName('express');

  final name = 'underline';
  final style2 = Style.values.byName(name);
}

Configuration

This rule is in the recommended preset, so it is on with preset: recommended or preset: opinionated. Add it to preset: core with prefer_enums_by_name: true.

To turn it off:

many_lints.yaml

rules:
  prefer_enums_by_name: false

To keep the rule on but skip certain paths, use per-rule exclude.

Related rules

• avoid_missing_enum_constant_in_map — Cover every enum constant in a map keyed by that enum.
• enum_constants_ordering — Keep enum constants in a configured order.
• avoid_accessing_collections_by_constant_index — Avoid accessing a collection by a constant index inside a loop.
• avoid_collection_equality_checks — Avoid comparing collections with == or != as it checks reference equality, not contents.