Converting dynamic JSON in flutter to models - json

Question

Converting a JSON to model would be a straight forward process. Let's consider a simple JOSON string as seen below;
jsonData ={'id':'1','name':'modelItem'}
It can be converted to model using below model class.
class Model{
final String? id;
final String? name;
Model({this.id,this.name});
}
But what about below JSON string?
jsonData= {'NYC':{'city code':'NYC','country code':'US'}}
Or another string like below?
jsondata= {'NYC': {'NYC':'NEW YORK'}}

Answer 1

Following is the solution for converting first JSON string
jsonData= {
'NYC':{'cityCode':'NYC','countryCode':'US'},
'SYD':{'cityCode':'SYD','countryCode':'AU'}
}
Solution for jsonData= {'NYC':{'city code':'NYC','country code':'US'}}
No matter how nested the JSON string data is, create a model class to convert inner map first. And then, try to work on the outer layer and so on.
class CityDetails{
final String? cityCode;
final String? countryCode;
CityDetails({this. cityCode, this. countryCode});
CityDetails.fromJson(Map<String,dynamic> parsedJson) {
for(var element in parsedJson.entries){
CityDetails(cityCode:element.key, countryCode:element.value);
}
}
}
Now, let's work on the outer layer which should give a list of CityDetails. Same method can be applied. However, here city code is repeated in the outer layer and it can be ignored. So the result should look like a List<CityDetails>.
class CityDataList{
final List<CityDetails> cityDetailsList;
CityDataList({this.cityDetailsList});
factory CityDataList.fromJson(Map<String,dynamic> parsedJson){
List<CityDetails> cityDetailsList=[];
for(var element in parsedJson.entries){
cityDetailsList.add(CityDetails(cityCode:element.key,
countryCode:element.value));
}
return CityDataList(cityDetailsList: cityDetailsList);
}
}
Solution for jsondata= {'NYC': {'NYC':'NEW YORK'}}. Solution for first problem would help to convert the outer JSON here, so it is not repeated here. Following helps to convert the inner JSON into a meaningful class.
class CityData{
final String? cityCode;
final String? cityName;
CityData({this.cityCode,this.cityName});
CityData.fromJson(Map<String,dynamic> parsedJson){
for(each element in parsedJson.entries){
CityData(citycode:element.key,cityName:element.value);
}
}
}