How to Adding New Data into JSON Dart? - flutter

Question

I have a JSON having some data as an array , and I wanna add
new data to JSON
This is My JSON structure
```[
{
"id":"JKT020",
"origin_time":"2020-06-30 12:00",
"location":"Jakarta, ID"
}
]```
I want to add new data so it can be like this
```[
{
"id":"JKT020",
"origin_time":"2020-06-30 12:00",
"location":"Jakarta, ID",
"flag":1
}
]```
Is it possible ? If it is can anyone tell me how to do that ? Thanks in advance.
And this is what I've been doing so far..
List data = json.decode(response.body);
for (int i = 0; i < data.length; i++) {
data.add(data[i]["flag"]=1);
print("object : " + data[i].toString());
}
});
It was printed like I want it, but return error in add line
The error said NoSuchMethodError: Class 'String' has no instance method '[]='

Answer 1

First of all, you have to Decode the JSON
var data=json.decode("Your JSON")
Now this is available as a list and map so you can add fields like
data[key]=value;
after that, you have to Encode it using json.encode
var data1=json.encode(data);
`

Answer 2

It's a good idea to get the JSON formatted and mapped to a Model. This will not only help to do null checks but also increase the readability of your code.
You can use a simple Model like
class myModel {
String id;
String originTime;
String location;
int flag;
myModel({this.id, this.originTime, this.location, this.flag});
myModel.fromJson(Map<String, dynamic> json) {
id = json['id'];
originTime = json['origin_time'];
location = json['location'];
flag = json['flag'];
}
Map<String, dynamic> toJson() {
final Map<String, dynamic> data = new Map<String, dynamic>();
data['id'] = this.id;
data['origin_time'] = this.originTime;
data['location'] = this.location;
data['flag'] = this.flag;
return data;
}
}