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fix(genui): explicitly enforce primitive types in JSON schema validator #955

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fix(genui): explicitly enforce primitive types in JSON schema validator
andrewkolos Jun 3, 2026
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clean up
andrewkolos Jun 3, 2026
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andrewkolos Jun 3, 2026
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fix(genui): accept whole-valued doubles as integers in schema validator
andrewkolos Jun 4, 2026
305aaa3
fix(genui): reject explicit null against non-nullable types
andrewkolos Jun 4, 2026
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1 change: 1 addition & 0 deletions packages/genui/CHANGELOG.md
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@
## 0.9.2
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@polina-c polina-c Jun 5, 2026 •
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You need to increase version. You did not get error about it, because validation arrived later than you created this fix.


- **Feature**: Updated example/README.md.
- **Fix**: `SurfaceDefinition.validate` now strictly enforces primitive data types, correctly identifying and rejecting malformed components (like numbers passed for strings) before they can cause fatal rendering crashes.

## 0.9.0

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30 changes: 30 additions & 0 deletions packages/genui/lib/src/model/ui_models.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -237,6 +237,36 @@ class SurfaceDefinition {
Map<String, dynamic> schema,
String path,
) {
if (schema case {'type': Object expectedType}) {
final List<String> types = expectedType is List
? expectedType.map((e) => e.toString()).toList()
: [expectedType.toString()];

final bool isValid = types.any(
(t) => switch (t) {
'string' => instance is String,
'number' => instance is num,
// A whole-valued double such as 42.0 is a valid integer.
'integer' =>
instance is num && (instance is int || instance.remainder(1) == 0),
'boolean' => instance is bool,
'object' => instance is Map,
'array' => instance is List,
'null' => instance == null,
_ => false,
},
);

if (!isValid) {
final Object actualType = instance?.runtimeType ?? 'null';
throw A2uiValidationException(
'Type mismatch. Expected $types, got $actualType',
surfaceId: surfaceId,
path: path,
);
}
}

if (instance == null) {
return;
}
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210 changes: 208 additions & 2 deletions packages/genui/test/model/ui_models_test.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -75,7 +75,6 @@ void main() {
components: {'test': component},
);

// Schema invalidating the component (e.g., expecting type "Button")
final schema = S.object(
properties: {
'components': S.list(
Expand Down Expand Up @@ -116,7 +115,214 @@ void main() {
},
);

surfaceDefinition.validate(schema); // Should not throw
surfaceDefinition.validate(schema); // Should not throw.
});

test('validate enforces primitive types: string', () {
final component = const Component(
id: 'test',
type: 'Text',
// int instead of string.
properties: {'text': 42},
);
final surfaceDefinition = SurfaceDefinition(
surfaceId: 's1',
components: {'test': component},
);

final schema = S.object(
properties: {
'components': S.list(
items: S.object(
properties: {
'component': S.string(constValue: 'Text'),
'text': S.string(),
},
),
),
},
);

expect(
() => surfaceDefinition.validate(schema),
throwsA(
isA<A2uiValidationException>().having(
(e) => e.message,
'message',
contains('Type mismatch'),
),
),
);
});
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test('validate enforces primitive types: boolean', () {
final component = const Component(
id: 'test',
type: 'Checkbox',
properties: {'checked': 'true'}, // string instead of bool.
);
final surfaceDefinition = SurfaceDefinition(
surfaceId: 's1',
components: {'test': component},
);

final schema = S.object(
properties: {
'components': S.list(
items: S.object(
properties: {
'component': S.string(constValue: 'Checkbox'),
'checked': S.boolean(),
},
),
),
},
);

expect(
() => surfaceDefinition.validate(schema),
throwsA(isA<A2uiValidationException>()),
);
});

test('validate enforces primitive types: '
'number vs integer', () {
final componentInt = const Component(
id: 'test1',
type: 'Slider',
properties: {'value': 42}, // Valid integer.
);
final componentDouble = const Component(
id: 'test2',
type: 'Slider',
properties: {'value': 42.5}, // Valid number, invalid integer.
);
// JSON decodes whole numbers like 42.0 to a Dart double; per JSON
// Schema a double with a zero fractional part is still an integer.
final componentWholeDouble = const Component(
id: 'test3',
type: 'Slider',
properties: {'value': 42.0},
);

final schema = S.object(
properties: {
'components': S.list(
items: S.object(
properties: {
'component': S.string(constValue: 'Slider'),
'value': S.integer(),
},
),
),
},
);

SurfaceDefinition(
surfaceId: 's1',
components: {'test1': componentInt},
).validate(schema);

SurfaceDefinition(
surfaceId: 's3',
components: {'test3': componentWholeDouble},
).validate(schema);

expect(
() => SurfaceDefinition(
surfaceId: 's2',
components: {'test2': componentDouble},
).validate(schema),
throwsA(isA<A2uiValidationException>()),
);
});

test('validate accepts both int and double for number type', () {
final schema = S.object(
properties: {
'components': S.list(
items: S.object(
properties: {
'component': S.string(constValue: 'Slider'),
'value': S.number(),
},
),
),
},
);

for (final value in const <Object>[42, 42.5]) {
SurfaceDefinition(
surfaceId: 's1',
components: {
'test': Component(
id: 'test',
type: 'Slider',
properties: {'value': value},
),
},
).validate(schema);
}
});

test('validate rejects explicit null for a non-nullable type', () {
final component = const Component(
id: 'test',
type: 'Text',
properties: {'text': null}, // null where a string is required.
);
final surfaceDefinition = SurfaceDefinition(
surfaceId: 's1',
components: {'test': component},
);

final schema = S.object(
properties: {
'components': S.list(
items: S.object(
properties: {
'component': S.string(constValue: 'Text'),
'text': S.string(),
},
),
),
},
);

expect(
() => surfaceDefinition.validate(schema),
throwsA(isA<A2uiValidationException>()),
);
});

test('validate enforces primitive types: array and object', () {
final component = const Component(
id: 'test',
type: 'List',
properties: {'items': 42}, // int instead of array.
);
final surfaceDefinition = SurfaceDefinition(
surfaceId: 's1',
components: {'test': component},
);

final schema = S.object(
properties: {
'components': S.list(
items: S.object(
properties: {
'component': S.string(constValue: 'List'),
'items': S.list(items: S.string()),
},
),
),
},
);

expect(
() => surfaceDefinition.validate(schema),
throwsA(isA<A2uiValidationException>()),
);
});
});

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