json_object_lite 3.0.0 json_object_lite: ^3.0.0 copied to clipboard
Allow use of JSON Maps in dot notation format without using mirrors.
///
/// This example is taken from the following article :-
/// http://www.dartlang.org/articles/json-web-service/
///
import 'package:json_object_lite/json_object_lite.dart';
// ignore_for_file: omit_local_variable_types
// ignore_for_file: unnecessary_final
// ignore_for_file: cascade_invocations
// ignore_for_file: avoid_print
/// The Dart 2.0 update has changed how JsonObjectLite is used, previously
/// you could do this :-
///
/// JsonObjectLite o = new JsonObjectLite.fromJSonString('........');
/// print(o.bob);
/// print(o.fred);
/// ....
///
/// If you do this now the o.bob line will be flagged by the analyser as
/// 'the getter bob is not defined.....' which is correct, its not.
/// This was suppressed in Dart 1.0 by annotating the class with 'proxy'.
/// This annotation has been deprecated in Dart 2.0 hence the error.
///
/// The fix for Dart 2.0 is to do this :-
/// dynamic o = new JsonObjectLite.fromJSonString('........');
///
/// Declaring the created object as dynamic gives the analyzer
/// no clues about the objects structure and hence it produces no errors.
///
/// This is unfortunate in the fact the user code has to change to
/// accommodate this but in the long run its cleaner as we now know that
/// we don't know the object structure if you see what I mean.
///
/// An example taken from the dartlang article for JSON object, found here
/// https://webdev.dartlang.org/articles/get-data/json-web-service.
class LanguageWebsite extends JsonObjectLite<dynamic> {
LanguageWebsite(); // default constructor (empty) implementation
factory LanguageWebsite.fromJsonString(String json) {
// from JSON constructor implementation
final LanguageWebsite languageWebsite =
LanguageWebsite(); // create an empty instance of this class
// Create an instance of JsonObjectLite, populated with the json string and
// injecting the _LanguageWebsite instance.
final JsonObjectLite<dynamic> jsonObject =
JsonObjectLite<dynamic>.fromJsonString(json, languageWebsite);
return jsonObject as LanguageWebsite; // return the populated JsonObject instance
}
factory LanguageWebsite.fromJsonObject(JsonObjectLite<dynamic> jsonObject) =>
JsonObjectLite.toTypedJsonObjectLite(jsonObject, LanguageWebsite()) as LanguageWebsite;
}
class Language extends JsonObjectLite<dynamic> {
Language(); // empty, default constructor
factory Language.fromJsonString(String json) =>
JsonObjectLite<dynamic>.fromJsonString(json, Language()) as Language;
// as _LangaugeWebsite, return an instance
// of JsonObjectLite, containing the json string and
// injecting a _Language instance
}
int main() {
const String responseText = '''
{
"language": "dart",
"targets": ["dartium","javascript"],
"website": {
"homepage": "www.dartlang.org",
"api": "api.dartlang.org"
}
}''';
final dynamic data = Language.fromJsonString(responseText);
// Tools can now validate the property access
print(data.language); // should be dart
print(data.targets[0]); // should be dartium
// Nested types are also strongly typed
final dynamic website =
LanguageWebsite.fromJsonObject(data.website); // contains a JsonObjectLite
print(website.homepage);
website.isImmutable = false; // Now we can extend it
website.homepage = 'http://www.dartlang.org';
print(website.homepage);
return 0;
}