Flutter update property of class with variable - flutter

Question

I'm new to flutter and despite my research I can't find the answers. How to update the values ​​of a class according to a dynamic variable.
For example in my User class I want to update the salary of my User according to a map. How to call the key to update the class ?
My class :
class Users{
List<User> user;
Users({this.user});
Users.fromJson(Map<String, dynamic> json) {
if (json['user'] != null) {
user= new List<User>();
json['user'].forEach((v) {
user.add(new User.fromJson(v));
});
}
}
Map<String, dynamic> toJson() {
final Map<String, dynamic> data = new Map<String, dynamic>();
if (this.user!= null) {
data['user'] = this.user.map((v) => v.toJson()).toList();
}
return data;
}
#override
String toString() {
return '{${this.user}}';
}
}
class User{
String name;
int gender;
num salary;
User(
{this.name,
this.gender,
this.salary,
});
User.fromJson(Map<String, dynamic> json) {
name= json['name'];
gender= json['gender'];
salary= json['salary'];
}
Map<String, dynamic> toJson() {
final Map<String, dynamic> data = new Map<String, dynamic>();
data['name'] = this.name;
data['gender'] = this.gender;
data['salary'] = this.salary;
return data;
}
#override
String toString() {
return '{ '
'${this.name},'
'${this.gender},'
'${this.salary},'
'}';
}
}
Here the function that calculate the new salary of my User and update this.
func_OrderedUsers(List<User> users)
{
List<User> _UsersInOrder;
if (users.length > 0)
{
users.forEach((user)
{
Map _params = {
"salary" : func_CalculateNewSalary(user)
};
func_UpdateItem(user, _params);
});
//... some code
}
And My function UpdateItem :
func_UpdateItem(var item, Map params)
{
if(params != null){
params.forEach((key, value)
{
if(value != null){
// Here is my problem !
// How to use the key variable ?
item.salary = value; // If I write directly the parameter it works (salary)
}
});
}
return item;
}

Answer 1

What you're trying to do is something that dart:mirrors would do. However, since you seem to be using flutter, this is not available for you to use.
Instead you'll have to manually map each key of your Map to a field in your object, just like in your fromJson constructor. You could add a method that does this within your class. Ex.
void updateFieldsFromMap(Map<String, dynamic> input) {
if(input['name'] != null) name = input['name'];
if(input['gender'] != null) gender = input['gender'];
if(input['salary'] != null) salary = input['salary'];
}

Answer 2

You can try to use factory
factory User.fromJson(Map<String, dynamic> json) {
return new User(
name: data['name'],
gender: data['gender'],
salary: data['salary'],
);
}