How to send with 'params.put' in Dart or Flutter JsonObjectLite - flutter

Question

In java it would be something like this ...
public Request compose(LoginDevice login) {
JSONObject params = new JSONObject();
try {
if (login.granType != null)
params.put("grant_type", login.granType);
if (login.clientId != null)
params.put("client_id", login.clientId);
} catch (JSONException e) {
e.printStackTrace();
}
return (Request)new BaseRequest("oauth/v2/token", params.toString(), new HashSet());
}
And in Dart and tried something similar but it doesn't work... the parameter 'put' does not exist in JsonObjectLite...
Request compose(LoginDevice login)
{
JsonObjectLite params = new JsonObjectLite();
try {
if (login.granType != null) {
params.put("grant_type", login.granType);
}
if (login.clientId != null) {
params.put("client_id", login.clientId);
}
} on JsonObjectLiteException catch (e) {
print(e);
}
return new BaseRequest("oauth/v2/token", params.toString(), new HashSet());
}
How could I do it? Thank you

Answer 1

The class JsonObjectLite doesn't contain the method put.
How you can understand dart doesn't is Java, in this cases your the class JsonObjectLite has a method called putIfAbsent, the implementation is the following
/// If [isImmutable] is false, or the key already exists,
/// then allow the edit.
/// Throw [JsonObjectLiteException] if we're not allowed to add a new
/// key
#override
void putIfAbsent(dynamic key, Function() ifAbsent) {
if (isImmutable == false || containsKey(key)) {
_objectData.putIfAbsent(key, ifAbsent);
} else {
throw const JsonObjectLiteException('JsonObject is not extendable');
}
}
look also the Source code
So an example of code should be the following
import 'package:json_object_lite/json_object_lite.dart';
class AuthorAnswer {
var _username;
var _status;
AuthorAnswer(this._username, this._status);
String get username => _username;
String get status => _status;
}
int main() {
var author = '#vincenzopalazzo';
var sentences = 'Follow me on Github';
var authorObject = AuthorAnswer(author, sentences);
try{
JsonObjectLite params = new JsonObjectLite();
params.isImmutable = false;
params.putIfAbsent("author", () => authorObject.username);
params.putIfAbsent("sencence", () => authorObject.status);
print(params.toString());
} on JsonObjectLiteException catch (err){
print('--------- ERROR ----------');
print(err);
}
return 0;
}
You should be set the params.isImmutable = false and after you can add your propriety, with your logic.
In my opinion, I don't see any motivation to use this library, dart have 2 types of the module to implement the serialization, and I think should better use it because on the web exist the documentation, like this dart json, flutter json
Inside the flutter app, there are also the line guides, for the small application you can use dart:convert:json also for the other you can use the json_serializable
I want to add also an example of dart:convert
/**
*
*/
import "dart:core";
import "dart:convert";
class ClassToJsonOne {
var _propOne;
var _propTwo;
ClassToJsonOne(this._propOne, this._propTwo);
Map<String, dynamic> toJSon() => {
'prop_one': _propOne,
'prop_two': _propTwo
};
ClassToJsonOne.fromJson(Map<String, dynamic> json):
_propOne = json['prop_one'],
_propTwo = json['prop_two'];
#override
String toString() => 'First Class: $_propOne, $_propTwo';
}
class ClassToJsonTwo{
var _propOne;
var _propTwo;
ClassToJsonTwo(this._propOne, this._propTwo);
Map<String, dynamic> toJSon() => {
'prop_one': _propOne,
'prop_two': _propTwo
};
ClassToJsonTwo.fromJson(Map<String, dynamic> json):
_propOne = json['prop_one'],
_propTwo = json['prop_two'];
#override
String toString() => 'Second Class: $_propOne, $_propTwo';
}
main(List<String> args) {
print('------- Declare Objecr -------\n');
var objectToJsonOne = ClassToJsonOne('I am the fist object', 'empty');
var objectToJsonTwo = ClassToJsonTwo('I contains the first object', 'empty');
String jsonStringObjOne = jsonEncode(objectToJsonOne.toJSon());
print('\n---------- Object one JSON format ---------\n');
print(jsonStringObjOne);
String jsonStringObjTwo = jsonEncode(objectToJsonTwo.toJSon());
print('\n---------- Object one JSON format ---------\n');
print(jsonStringObjTwo);
print('\n---------- DECODE JSON to OBJECT ---------\n');
var fromJsonObjectOne = jsonDecode(jsonStringObjOne);
print(fromJsonObjectOne.toString());
var fromJsonObjectTwo = jsonDecode(jsonStringObjTwo);
print(fromJsonObjectTwo.toString());
}
Inside the classes, you can see the following methods
Map<String, dynamic> toJSon() => {
'prop_one': _propOne,
'prop_two': _propTwo
};
ClassToJsonTwo.fromJson(Map<String, dynamic> json):
_propOne = json['prop_one'],
_propTwo = json['prop_two'];
The result of the method toJSon, you should be pass to the method of the library jsonEncode and when you go to deserialize you can use the library method jsonDecode(youtStringJSOn) and the result you can pass to the method of your class fromJson.
In addition, you can configure the library json_serializable.
In conclusion, I want to fix my comment
I think the json_serializable worked how GSON, I can make an example for you, on this day.
On flutter, documentation has reported this text
Is there a GSON/Jackson/Moshi equivalent in Flutter?
The simple answer is no.
Such a library would require using runtime reflection, which is disabled in Flutter. Runtime reflection interferes with tree shaking, which Dart has supported for quite a long time. With tree shaking, you can “shake off” unused code from your release builds. This optimizes the app’s size significantly.
Since reflection makes all code implicitly used by default, it makes tree shaking difficult. The tools cannot know what parts are unused at runtime, so the redundant code is hard to strip away. App sizes cannot be easily optimized when using reflection.
Although you cannot use runtime reflection with Flutter, some libraries give you similarly easy-to-use APIs but are based on code generation instead. This approach is covered in more detail in the code generation libraries section.
you can found the source code inside this answer here