The method 'detach' isn't defined for the class 'FocusScopeNode' #31784

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1. HansMuller commented on Apr 29, 2019

   

   HansMuller

   on Apr 29, 2019

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   CC @gspencergoog
2. gspencergoog commented on Apr 29, 2019

   

   gspencergoog

   on Apr 29, 2019

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   Yes, this is due to a breaking change in FocusScopeNode. Are you hosting the focus node (calling reparentIfNeeded), or just creating one to pass in to a TextField or FocusScope widget?
3. gspencergoog commented on Apr 29, 2019

   

   gspencergoog

   on Apr 29, 2019

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   Actually, if you're calling detach, you're probably hosting the node. There have been several changes in the way focus nodes work for widgets that are hosting nodes:

   1. In order to host a node, you need to attach to the node in your initState method to create a FocusAttachment, passing in the context:

     FocusScopeNode _node;
     FocusAttachment _nodeAttachment;
     @override
     void initState() {
       super.initState();
       _node = FocusNode();
       _nodeAttachment = _node.attach(context);
     }

   2. In your dispose, you need to call dispose on the focus scope node:

     @override
     void dispose() {
       // The attachment will automatically be detached in dispose().
       _node.dispose();
       super.dispose();
     }

   3. In your build method, you will be calling reparent instead of reparentIfNeeded:

     @override
     Widget build(BuildContext context) {
       _nodeAttachment.reparent();
       return ...;
     }

   4. Where you called detach before on the focus scope node, you will now call detach on the focus attachment.

     _nodeAttachment.detach();

   However, I'd like to also point out that with the new focus API, it's less common to need to host a node yourself: you can just use the Focus and FocusScope widgets to handle all of the hosting mechanics (the things above), and simply pass the scope node to a FocusScope widget instead. You will still need to call dispose on a node that you own yourself. Even owning your own focus node isn't as necessary, unless you need an ancestor widget to be able to tell descendant nodes to be focused, since the Focus and FocusScope widgets will create and dispose of their own nodes if you don't supply one.
4. AndreaMiotto commented on Apr 30, 2019

   

   AndreaMiotto

   on Apr 30, 2019

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   It is still unclear to me how to close the keyboard on the textfield, at the moment I'm focusing a new FocusNode() like this:

   FocusScope.of(context).requestFocus(new FocusNode());

   But I know that this is not the proper way.
5. gspencergoog commented on Apr 30, 2019

   

   gspencergoog

   on Apr 30, 2019

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   You can use this: FocusScope.of(context).unfocus()
6. gspencergoog

   closed this as completedin #31909on May 1, 2019
7. github-actions commented on Aug 30, 2021

   

   github-actionsbot

   on Aug 30, 2021

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   This thread has been automatically locked since there has not been any recent activity after it was closed. If you are still experiencing a similar issue, please open a new bug, including the output of flutter doctor -v and a minimal reproduction of the issue.
8. github-actions

   locked as resolved and limited conversation to collaborators on Aug 30, 2021