CODEWITHSUNDEEP
flutterdart
Eric Anderson
Eric Anderson

Reputation: 341

How to initialize a nested object in Dart. NoSuchMethodError: invalid member on null: 'user'

I'm getting a NoSuchMethodError: invalid member on null: 'user' error when I execute the following. I assume I'm missing a constructor or setter or initializing wrong.

class Mac{
  MacUser user;

  Mac({
    this.user
  });
}

class MacUser{
  String username;
  String password;

  MacUser({
    this.username, 
    this.password,
  });
}

void main(){
  Mac mac;
  mac.user.username = "root"; // NoSuchMethodError: invalid member on null: 'user'
  mac.user.password = "root";
}

Upvotes: 1

Views: 1370

Answers (2)

Arun R. Prajapati
Arun R. Prajapati

Reputation: 2802

Mac mac =  new Mac(user: new MacUser()); // this line will Create a Null Object as you may or may not have both values at this time later on you can edit those value by below code
mac.user.username = "root";
mac.user.password = "root";

Upvotes: 0

OMi Shah
OMi Shah

Reputation: 6186

You're trying to set the property on a null object. You need to define some value first before changing:

Example:

Mac mac = new Mac(user: MacUser(username: "username", password: "password")); // initialize some value first

  mac.user.username = "root";
  mac.user.password = "root";

Upvotes: 1

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