Compare List with Value in Dart / Flutter

Question

I am trying to compare an input value to a list of items in Dart language, however, it does not seem to work.

Method:

  String validateStoreNumber(String value) {

    List<String> storeList = ['55', '56', '88'];

    // String patttern = r'(^[a-zA-Z ]*$)';
    RegExp regExp = new RegExp(r'^[+-]?([0-9]+([.][0-9]*)?|[.][0-9]+)$');
    if (value.length == 0) {
      return "car number is required";
    } else if (!regExp.hasMatch(value)) {
      return "Accepts only numbers";
    } else if (value.length != 2){

      return "car number must have 2 digits";
    } else if (value != storeList.contains(value)){

      return "Not our model";
    }
    return null;
  }

What is the input and what is the expected output? What does "does not seem to work" mean? — Günter Zöchbauer
– Günter Zöchbauer, Commented Jul 24, 2018 at 16:31
This line } else if (value != storeList.contains(value)){ looks odd. I'd expect it to be } else if (!storeList.contains(value)){ or similar. What is this code supposed to do? — Günter Zöchbauer
– Günter Zöchbauer, Commented Jul 24, 2018 at 16:32
That is a validation method. I have a form that takes an input (value in this case), validates it and then takes the user to another screen. I am trying to get this input and compare it against a hard coded list of numbers as in storeList ? — Zeusox
– Zeusox, Commented Jul 24, 2018 at 16:33
That was the whole problem. But now it works, Dart syntax is a little bit different that what I am used to. Thanks a lot ! — Zeusox
– Zeusox, Commented Jul 24, 2018 at 17:17

dakamojo · Accepted Answer · 2018-07-24 17:54:34Z

4

This line...

else if (value != storeList.contains(value))

Is the problem. The left side "value" is a string, and the right side "contains" is a boolean. You are comparing a string to a boolean.

I think you want this...

else if (!storeList.contains(value))

answered Jul 24, 2018 at 17:54

dakamojo

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1 Comment

Zeusox Over a year ago

Thanks, correct answer has been provided by Günter Zöchbauer, but you added explanation as well.

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