Question

我有一个ListView，其中包含产品列表。在ListView中点击ListTile时，将显示一个AlertDialog，其中包含一个TextFormField，允许用户编辑产品名称。

@override
Widget build(BuildContext context) {
  return ListView.builder(
      itemCount: _products.length,
      itemBuilder: (context, index) {
        Product product = _products[index];

        return ListTile(
          title: Text(product.name),
          onTap: () {
            showDialog(
              context: context,
              builder: (BuildContext context) => AlertDialog(
                    title: Text("Edit name"),
                    content: TextFormField(
                      initialValue: product.name,
                      maxLines: 1,
                    ),
                    actions: <Widget>[
                      FlatButton(
                        child: Text("Save"),
                        onPressed: () {
                          // Save logic
                        },
                      ),
                    ],
                  ),
            );
          },
        );
      });
}

问题是，当点击TextFormField时，应用程序立即因以下错误而崩溃：

══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════
The following assertion was thrown building Builder(dirty):
Looking up a deactivated widget's ancestor is unsafe.
At this point the state of the widget's element tree is no longer stable. To safely refer to a
widget's ancestor in its dispose() method, save a reference to the ancestor by calling
inheritFromWidgetOfExactType() in the widget's didChangeDependencies() method.

有人可以建议吗？

Answer 1

从AlertDialog创建为单独的小部件，这应该可以解决问题

检查此代码：

class MyDialog extends StatefulWidget{
  final String productName;
  MyDialog({this.productName})
}

class MyDialodState extends State<MyDialog>{
  @override
  Widget build(BuildContext context) {
    reutrn AlertDialog(
                    title: Text("Edit name"),
                    content: TextFormField(
                      initialValue: widget.productName,
                      maxLines: 1,
                    ),
                    actions: <Widget>[
                      FlatButton(
                        child: Text("Save"),
                        onPressed: () {
                          // Save logic
                        },
                      ),
                    ],
                  ),
            );
  }
}

// your onTap on ListTile should look something like this:
return ListTile(
          title: Text(product.name),
          onTap: () {
            showDialog(
              context: context,
              builder: (BuildContext context) => MyDialog(
                    productName:product.name
              );
          },
        );

单击TextFormField时应用程序崩溃

1 个答案: