Flutter: Multiple widgets used the same GlobalKey

Question

When I run this code I'm getting an error: Multiple widgets used the same GlobalKey. So I can fix this issue. How I can pass dynamically keys to my listview.Builder. is it possible to pass?. Here is simplified version my code:


  GlobalKey<AutoCompleteTextFieldState<String>> key0 = new GlobalKey();

  @override
  Widget build(BuildContext context) {
    return M Scaffold(
        appBar: appBar,
        body: SingleChildScrollView(
          child: Container(
            child: ListView.builder(
               itemCount: 3,
               itemBuilder: (context, index) {
                return  SimpleAutoCompleteTextField(
                  key: key0,
                  suggestions: suggestions,
                  textChanged: (text) => print(text),
                  clearOnSubmit: false,
                  textSubmitted: (text) => print(text)
                ),
              }
            ),
          ),
        ),

    );
  }

score 3 · Answer 1 · answered Jun 11 '20 at 13:42

3

Pass index as your value

  key: ValueKey(index),

answered Jun 11 '20 at 13:42

Jitesh Mohite

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Can you share the code of AutoCompleteTextFieldState? without it can't help you much, but you have to add key in that class like SimpleAutoCompleteTextField(Key key,....) – Jitesh Mohite Jun 11 '20 at 14:09
it's a package https://pub.dev/packages/autocomplete_textfield – Leewan Jun 11 '20 at 14:32
Error is : The argument type 'ValueKey' can't be assigned to the parameter type 'GlobalKey>'. – Leewan Jun 11 '20 at 14:37
Were you able to solve this issue? – Davis Nov 24 '21 at 22:50

score 1 · Answer 2 · answered Jun 11 '20 at 13:56

GlobalKey must be unique across the entire application.

You cannot simultaneously include two widgets in the tree with the same global key. Attempting to do so will assert at runtime.

It means that multiple elements can't use the same key. Here's a short video about keys in Flutter and not that short article about using keys, including GlobalKey's.

What you should do in this case is to derive keys of each element from their uniquely defining features such as content or some ID.

Things to note:

1.

Key('AAA') == Key('AAA'); // true

it means that you don't have to create Key objects outside of your build function and can go with just:

return SimpleAutoCompleteTextField(
  key: Key(itemId),

or even rather ValueKey(itemData) in your case: ValueKey.

GlobalKey's are relatively expensive and if you don't explicitly need to move them from one place of the app to another, prefer regular Key.
Don't derive keys from indices. It's considered a bad practice because it will lead to misbehavior when you try to reorder existing widgets in the same subtree.

Key() doesn't have widget size and some of data. Which globayKey has. How can I achive that without gloableKey — ÄR Âmmãř Żąîñh, Jul 20 '21 at 03:43

Flutter: Multiple widgets used the same GlobalKey

2 Answers2

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