Dart - Parse Nested Json Arrays - flutter

Question

Getting errors after trying to convert nested JSON data using dart's factory concept.
Here I have two classes to handle the json data, but still getting this error:
Exception has occurred.
_TypeError (type 'FormatException' is not a subtype of type 'Map')
Here is the code:
class BodyResponse {
final Map<String, dynamic> message;
BodyResponse({
this.message
});
factory BodyResponse.fromJson(Map<String, dynamic> json) {
return BodyResponse(message: json['message']);
}
}
class ErrorResponse {
final BodyResponse body;
final int status;
final String contentType;
final bool success;
ErrorResponse({
this.body, this.status, this.contentType, this.success
});
factory ErrorResponse.fromJson(Map<String, dynamic> json) {
return ErrorResponse(
body: BodyResponse.fromJson(json['body']),
status: json['status'],
contentType: json['content_type'],
success: json['success']
);
}
}
ErrorResponse errors = ErrorResponse.fromJson("""
{
"body": {
"message": "Some one has already taken this username(fooBar), please try again with a new username."
},
"status": 500,
"content_type": "application\/json",
"success": false
}
""");
print(errors);
What could go wrong here?

Answer 1

Modified most of your code here. Hope that this is what you tried to achieve.
import 'dart:convert';
class BodyResponse {
final String message;
BodyResponse({this.message});
BodyResponse.fromJson(Map<String, dynamic> json):
message = json['message'];
factory BodyResponse.fromString(String encodedJson) {
return BodyResponse.fromJson(json.decode(encodedJson));
}
Map<String, dynamic> toJson() => {
"message": message,
};
String toString() => json.encode(this.toJson());
}
class ErrorResponse {
final BodyResponse body;
final int status;
final String contentType;
final bool success;
ErrorResponse({this.body, this.status, this.contentType, this.success});
ErrorResponse.fromJson(Map<String, dynamic> json):
body = BodyResponse.fromJson(json['body']),
status = json['status'],
contentType = json['content_type'],
success = json['success'];
factory ErrorResponse.fromString(String encodedJson) {
return ErrorResponse.fromJson(json.decode(encodedJson));
}
Map<String, dynamic> toJson() => {
"body": body.toJson(),
"status": status,
"contentType": contentType,
"success": success,
};
String toString() => json.encode(this.toJson());
}
void main() {
ErrorResponse errors = ErrorResponse.fromString("""
{
"body": {
"message": "Some one has already taken this username(fooBar), please try again with a new username."
},
"status": 500,
"content_type": "application\/json",
"success": false
}
""");
print(errors);
}
Let me know if this helped.