schemantic 0.0.1-dev.5
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A general-purpose builder for generating type-safe data classes and JSON schemas from abstract definitions.
example/schemantic_example.dart
// Copyright 2025 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
import 'package:schemantic/schemantic.dart';
part 'schemantic_example.schema.g.dart';
@Schematic()
abstract class AddressSchema {
String get street;
String get city;
String get zipCode;
}
/// Define a schema using the @Schematic annotation.
/// This will generate a concrete [User] class and a [UserType] utility.
@Schematic()
abstract class UserSchema {
String get name;
int? get age;
bool get isAdmin;
// Nested schema
AddressSchema? get address;
}
void main() async {
// 1. Create an instance using the generated class
final address = Address.from(
street: '123 Main St',
city: 'Springfield',
zipCode: '62704',
);
final user = User.from(
name: 'Alice',
age: 30,
isAdmin: true,
address: address,
);
print('--- Instance ---');
print('Name: ${user.name}');
print('Age: ${user.age}');
print('Is Admin: ${user.isAdmin}');
print('Address: ${user.address?.street}, ${user.address?.city}');
// 2. Serialize to JSON
final json = user.toJson();
print('\n--- JSON Serialization ---');
print(json);
// Output: {name: Alice, age: 30, isAdmin: true, address: {street: 123 Main St, city: Springfield, zipCode: 62704}}
// 3. Parse from JSON
final parsed = UserType.parse({
'name': 'Bob',
'isAdmin': false,
'address': {
'street': '456 Elm St',
'city': 'Shelbyville',
'zipCode': '62705',
},
});
print('\n--- JSON Parsing ---');
print('Parsed Name: ${parsed.name}'); // Bob
print('Parsed City: ${parsed.address?.city}'); // Shelbyville
// 4. Access JSON Schema at runtime
final schema = UserType.jsonSchema();
print('\n--- JSON Schema ---');
print(schema.toJson());
// 5. Validation
print('\n--- Validation ---');
// Valid data
// Valid data
final validData = <String, dynamic>{
'name': 'Charlie',
'isAdmin': true,
'address': <String, dynamic>{
'street': '789 Oak St',
'city': 'Capital City',
'zipCode': '62706',
},
};
final validResult = await schema.validate(validData);
if (validResult.isEmpty) {
print('✅ Data is valid.');
} else {
print('❌ Validation failed: $validResult');
}
// Invalid data (missing required field 'isAdmin' and invalid nested field)
final invalidData = <String, dynamic>{
'name': 'Dave',
'address': <String, dynamic>{
// Missing required street, city, zipCode
},
};
final invalidResult = await schema.validate(invalidData);
if (invalidResult.isNotEmpty) {
print('✅ Correctly detected invalid data:');
for (final error in invalidResult) {
print(' - $error');
}
}
}