SpecifyUnknownEnumValueRule class

Warns when an enum-typed field inside a @JsonSerializable() class has no unknownEnumValue fallback configured on its @JsonKey/@JsonEnum annotation.

Since: v14.5.0 | Rule version: v1

json_serializable lets an enum field declare @JsonKey(unknownEnumValue: MyEnum.unknown) (or a class-level @JsonEnum(unknownEnumValue: ...)) so that when the backend sends an enum string not present in the generated _$MyEnumEnumMap, deserialization falls back to the configured sentinel value instead of throwing a CheckedFromJsonException. Backend teams routinely add new enum values ahead of client releases; a client without this fallback crashes on any payload carrying the new value — including for enums as innocuous as a "notification type" or "status" field, which can crash the app open on the home screen. This rule flags enum fields (including List<Enum> and Map<K, Enum> fields, checked on the map's value type — an enum-typed map key is not checked) inside a class carrying @JsonSerializable() and/or a class-level @JsonEnum(...) whose own @JsonKey (or absence of one) carries no unknownEnumValue, and the enclosing class has no class-level @JsonEnum(unknownEnumValue: ...) covering it. A class annotated @JsonSerializable(createFactory: false) is out of scope entirely — no .fromJson decoder is generated, so there is no decode path that can throw. A field is also exempt when its @JsonKey carries ignore: true, includeFromJson: false, or a custom fromJson: converter — each removes the field from the generated decoder's enum-map lookup, so unknownEnumValue would not apply to it. Detection is scoped to annotations visible in the same file as the field declaration; an @JsonEnum(unknownEnumValue: ...) placed directly on the enum declaration in a different file is not currently tracked — see the Alternatives section of the originating proposal for the reasoning. Annotation matching is by simple name only (with basic support for a prefixed import, e.g. @json.JsonSerializable()), not by resolved import — an unrelated local class that happens to be named JsonSerializable/JsonKey/JsonEnum would also match.

BAD:

enum NotificationType { message, reminder, promo }

@JsonSerializable()
class NotificationPayload {
  // Enum field has no unknownEnumValue fallback; a new backend value
  // (e.g. "digest") crashes deserialization instead of degrading
  // gracefully.
  final NotificationType type;

  NotificationPayload(this.type);

  factory NotificationPayload.fromJson(Map<String, dynamic> json) =>
      _$NotificationPayloadFromJson(json);
}

GOOD:

enum NotificationType { message, reminder, promo, unknown }

@JsonSerializable()
class NotificationPayload {
  // Unrecognized backend values fall back to NotificationType.unknown
  // instead of throwing.
  @JsonKey(unknownEnumValue: NotificationType.unknown)
  final NotificationType type;

  NotificationPayload(this.type);

  factory NotificationPayload.fromJson(Map<String, dynamic> json) =>
      _$NotificationPayloadFromJson(json);
}
Inheritance

Properties

accuracyTarget → AccuracyTarget?
Optional accuracy target for this rule (for documentation and tooling). Does not enforce; used by reports and rule-audit scripts.
no setterinherited
applicableFileTypes → Set<FileType>?
The file types this rule applies to.
no setterinherited
canUseParsedResult → bool
Indicates whether this analysis rule can work with just the parsed information or if it requires a resolved unit.
no setterinherited
certIds → List<String>
CERT coding standard identifiers (e.g. STR02-C). Populate only where there is a clear mapping; leave empty for most rules initially.
no setterinherited
code → LintCode
The lint code for this rule.
no setterinherited
configAliases → List<String>
Alternate config keys that can be used to reference this rule.
no setterinherited
conflictingRules → List<String>
Curated opposite/competing rule names.
no setterinherited
cost → RuleCost
The estimated execution cost of this rule.
no setteroverride
cweIds → List<int>
CWE identifiers this rule helps prevent or detect. https://cwe.mitre.org/ — e.g. CWE-798 (Hardcoded Credentials).
no setterinherited
description → String
Short description suitable for display in console output and IDEs.
finalinherited
diagnosticCode → DiagnosticCode
The code to report for a violation.
no setterinherited
diagnosticCodes → List<DiagnosticCode>
The diagnostic codes associated with this analysis rule.
no setterinherited
documentationUrl → String
Returns the documentation URL for this rule.
no setterinherited
effectiveSeverity → DiagnosticSeverity?
Get the effective severity for this rule, considering overrides.
no setterinherited
exampleBad → String?
Short code example that VIOLATES this rule (shown in CLI walkthrough).
no setterinherited
exampleGood → String?
Short code example of COMPLIANT code (shown in CLI walkthrough).
no setterinherited
fixGenerators → List<SaropaFixGenerator>
Fix producer generators for this rule.
no setterinherited
hashCode → int
The hash code for this object.
no setterinherited
hyphenatedName → String
Returns the rule name in hyphenated format for display.
no setterinherited
impact → LintImpact
Forward-compatibility crash risk, but conditional on the backend actually shipping a new enum value — not a deterministic failure at the call site, so this sits at warning rather than error, matching the sibling require_json_decode_try_catch json-decode-safety rule.
no setteroverride
incompatibleRules → List<String>
A list of incompatible rule names.
no setterinherited
isDisabled → bool
Check if this rule is disabled via configuration.
no setterinherited
maximumLineCount → int
Maximum line count for this rule to run.
no setterinherited
minimumLineCount → int
Minimum line count for this rule to run.
no setterinherited
name → String
The rule name.
finalinherited
owasp → OwaspMapping?
OWASP categories this rule helps prevent.
no setterinherited
pubspecVisitor → PubspecVisitor?
A visitor that visits a Pubspec to perform analysis.
no setterinherited
relatedRules → List<String>
Curated "see also" rule names for discoverability in docs/IDE tooling.
no setterinherited
reporter ← DiagnosticReporter
Sets the DiagnosticReporter for the CompilationUnit currently being visited.
no getterinherited
requiredPatterns → Set<String>?
String patterns that must be present in the file for this rule to run.
no setteroverride
requiresAsync → bool
Whether this rule only applies to async code.
no setterinherited
requiresBlocImport → bool
Whether this rule only applies to files that import Bloc.
no setterinherited
requiresClassDeclaration → bool
Whether this rule only applies to files with class declarations.
no setterinherited
requiresFlutterImport → bool
Whether this rule only applies to files that import Flutter.
no setterinherited
requiresImports → bool
Whether this rule only applies to files with imports.
no setterinherited
requiresMainFunction → bool
Whether this rule only applies to files with a main() function.
no setterinherited
requiresProviderImport → bool
Whether this rule only applies to files that import Provider.
no setterinherited
requiresRiverpodImport → bool
Whether this rule only applies to files that import Riverpod.
no setterinherited
requiresWidgets → bool
Whether this rule only applies to Flutter widget code.
no setterinherited
ruleStatus → RuleStatus
Lifecycle status. Default RuleStatus.ready. Use RuleStatus.beta for new or heuristic-heavy rules; RuleStatus.deprecated for sunset.
no setterinherited
ruleType → RuleType?
Semantic type of this rule. Default null = unspecified (legacy). When set, used for quality gates, accuracy targets, and reporting.
no setteroverride
runtimeType → Type
A representation of the runtime type of the object.
no setterinherited
skipExampleFiles → bool
Whether to skip example files (example/**).
no setterinherited
skipFixtureFiles → bool
Whether to skip fixture files (fixture/, fixtures/).
no setterinherited
skipGeneratedCode → bool
Whether to skip generated files (*.g.dart, *.freezed.dart, *.gen.dart).
no setterinherited
skipTestFiles → bool
Whether to skip test files (*_test.dart, test/**).
no setterinherited
state → RuleState
The state of this analysis rule.
finalinherited
supersedesRules → List<String>
Rule names this rule supersedes/replaces.
no setterinherited
tags → Set<String>
Tags for filtering and discovery (e.g. in docs, IDE, or CI). Examples: 'performance', 'accessibility', 'suspicious', 'convention'.
no setteroverride
testRelevance → TestRelevance
How this rule relates to test files.
no setterinherited
usesTypeResolution → bool
Whether this rule triggers lazy cross-library type resolution in the analyzer (e.g. .staticType, .library, .allSupertypes, .enclosingElement).
no setterinherited

Methods

noSuchMethod(Invocation invocation) → dynamic
Invoked when a nonexistent method or property is accessed.
inherited
registerNodeProcessors(RuleVisitorRegistry registry, RuleContext context) → void
Registers node processors in the given registry.
inherited
reportAtNode(AstNode? node, {List<Object> arguments = const [], List<DiagnosticMessage>? contextMessages}) → Diagnostic?
Reports a diagnostic at node with message arguments and contextMessages.
inherited
reportAtOffset(int offset, int length, {List<Object> arguments = const [], List<DiagnosticMessage>? contextMessages}) → Diagnostic
Reports a diagnostic at offset, with length, with message arguments and contextMessages.
inherited
reportAtPubNode(PubspecNode node, {List<Object> arguments = const [], List<DiagnosticMessage> contextMessages = const []}) → Diagnostic
Reports a diagnostic at Pubspec node, with message arguments and contextMessages.
inherited
reportAtSourceRange(SourceRange sourceRange, {List<Object> arguments = const [], List<DiagnosticMessage>? contextMessages}) → Diagnostic
Reports a diagnostic at sourceRange, with message arguments and contextMessages.
inherited
reportAtToken(Token token, {List<Object> arguments = const [], List<DiagnosticMessage>? contextMessages}) → Diagnostic?
Reports a diagnostic at token, with message arguments and contextMessages.
inherited
runWithReporter(SaropaDiagnosticReporter reporter, SaropaContext context) → void
Override this method to implement your lint rule.
override
shouldSkipFile(String path) → bool
Check if a file path should be skipped based on context settings.
inherited
toString() → String
A string representation of this object.
inherited

Operators

operator ==(Object other) → bool
The equality operator.
inherited