The method 'toLowerCase' was called on null. Receiver: null Tried calling: toLowerCase()

Question

I am getting this error in my code and i dont know how to fix:

The method 'toLowerCase' was called on null.
    Receiver: null
    Tried calling: toLowerCase()

this is where the error is coming from

buildSuggestions(String query){
    final List<UbuildSuggestions(String query){
    final List<UserName> suggestionList = query.isEmpty
        ? []
        : userList.where((UserName user) {
          String _getUsername = user.username.toLowerCase();
          String _query = query.toLowerCase();
          String _getName = user.name.toLowerCase();
          bool matchesUsername = _getUsername.contains(_query);
          bool matchesName = _getName.contains(_query);

          return (matchesUsername || matchesName);
    }).toList();

As error message mentions you are trying to apply a function over a null value, so you should first check that variable before applying any another function. [This post](https://stackoverflow.com/questions/54031804/what-are-the-double-question-marks-in-dart) can be of help to you. — Ουιλιαμ Αρκευα, Jan 12 '21 at 18:55
[This article](https://dart.dev/null-safety) explains about dealing with `null` values in more detail. Read it please. — Ουιλιαμ Αρκευα, Jan 12 '21 at 19:24
Does this answer your question? [What is a NoSuchMethod error and how do I fix it?](https://stackoverflow.com/questions/64049102/what-is-a-nosuchmethod-error-and-how-do-i-fix-it) — nvoigt, Jan 13 '21 at 07:46

score 0 · Accepted Answer · answered Jan 13 '21 at 01:47

0

try

  String _getUsername = (user?.username??"").toLowerCase();
  String _query = (query??"").toLowerCase();
  String _getName = (user?.name??"").toLowerCase();

If the object is null, it will pass the empty string

answered Jan 13 '21 at 01:47

Sam Chan

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The method 'toLowerCase' was called on null. Receiver: null Tried calling: toLowerCase()

1 Answers1