How to parse a nested JSON dictionary (map) - json

Question

I am trying to read a JSON code which is compatible with a Swift program into a flutter app. The structure is like this:
{
"tagDict" : {
"abc" : {
"helpHdr" : "short text1",
"helpText" : "long text1"
},
"def" : {
"helpHdr" : "short text2",
"helpText" : "long text2"
}
}
}
This creates in Swift a dictionary and shall create a map in Dart of the type {key : {helpHdr, helpText}}. A variable based on this should enable label = myVariable[tag].helpHdr, or staying with the example label = myVariable["abc"].helpHdr should assign "short text1" to label
To parse nested arrays I am using this, however, no clue how to transfer this to such a nested map.
class MyClass {
List<MySubClass> myArray;
MyClass({
this.myArray,
});
factory MyClass.fromJson(Map<String, dynamic> parsedJson){
var list = parsedJson['myArray'] as List;
List<MySubClass> listObject = list.map((i) => MySubClass.fromJson(i)).toList();
return new MyClass(
myArray: listObject,
);
}
}
class MySubClass {
int id;
String text1;
String text2;
MySubClass({
this.id,
this.text1,
this.text2,
});
factory MySubClass.fromJson(Map<String, dynamic> parsedJson){
return new MySubClass(
id: parsedJson['id'],
text1: parsedJson['text1'],
text2: parsedJson['text2'],
);
}
}

Answer 1

If I'm correct you want to parse your json into Data class object. If that's right then you can try this
void main() {
List<MyClass> myClassList = new List<MyClass>();
Map map = {
"tagDict": {
"abc": {"helpHdr": "short text1", "helpText": "long text1"},
"def": {"helpHdr": "short text2", "helpText": "long text2"}
}
};
map['tagDict'].forEach((key, value) {
value['id'] = key;
myClassList.add(MyClass.fromJson(value));
});
myClassList.forEach((myClass) {
print(myClass.id);
print(myClass.helpHdr);
print(myClass.helpText);
print("--------------------\n");
});
}
class MyClass {
String id;
String helpHdr;
String helpText;
MyClass({this.id, this.helpHdr, this.helpText});
MyClass.fromJson(Map<String, dynamic> json) {
id = json['id'];
helpHdr = json['helpHdr'];
helpText = json['helpText'];
}
Map<String, dynamic> toJson() {
final Map<String, dynamic> data = new Map<String, dynamic>();
data['id'] = this.id;
data['helpHdr'] = this.helpHdr;
data['helpText'] = this.helpText;
return data;
}
}
This is the Output:
abc
short text1
long text1
--------------------
def
short text2
long text2
--------------------

Answer 2

class TagRes {
TagDict tagDict;
TagRes({this.tagDict});
TagRes.fromJson(Map<String, dynamic> json) {
tagDict =
json['tagDict'] != null ? new TagDict.fromJson(json['tagDict']) : null;
}
Map<String, dynamic> toJson() {
final Map<String, dynamic> data = new Map<String, dynamic>();
if (this.tagDict != null) {
data['tagDict'] = this.tagDict.toJson();
}
return data;
}
}
class TagDict {
Abc abc;
Abc def;
TagDict({this.abc, this.def});
TagDict.fromJson(Map<String, dynamic> json) {
abc = json['abc'] != null ? new Abc.fromJson(json['abc']) : null;
def = json['def'] != null ? new Abc.fromJson(json['def']) : null;
}
Map<String, dynamic> toJson() {
final Map<String, dynamic> data = new Map<String, dynamic>();
if (this.abc != null) {
data['abc'] = this.abc.toJson();
}
if (this.def != null) {
data['def'] = this.def.toJson();
}
return data;
}
}
class Abc {
String helpHdr;
String helpText;
Abc({this.helpHdr, this.helpText});
Abc.fromJson(Map<String, dynamic> json) {
helpHdr = json['helpHdr'];
helpText = json['helpText'];
}
Map<String, dynamic> toJson() {
final Map<String, dynamic> data = new Map<String, dynamic>();
data['helpHdr'] = this.helpHdr;
data['helpText'] = this.helpText;
return data;
}
}

Answer 3

Based on Tipu's answer, I came up with the following code which creates the intended dictionary (or map in Dart - why couldn't they stick to standard terminology like arrays etc?!)
class TaskTags {
var tagDict = Map<String, TaskTag>();
TaskTags({
this.tagDict,
});
factory TaskTags.fromJson(Map<String, dynamic> json){
var innerMap = json['tagDict'];
var tagMap = Map<String, TaskTag>();
innerMap.forEach((key, value) {
tagMap.addAll({key: TaskTag.fromJson(value)});
});
return new TaskTags(
tagDict: tagMap,
);
}
}
class TaskTag {
String helpHdr;
String helpText;
TaskTag({
this.helpHdr,
this.helpText,
});
factory TaskTag.fromJson(Map<String, dynamic> json){
return new TaskTag(
helpHdr: json['helpHdr'],
helpText: json['helpText'],
);
}
}
This creates the following map
{"abc“ : {helpHdr: "short text1", helpText: "long text1"}, "def“ : {helpHdr: "short text2", helpText: "long text2"}}