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社区首页 >问答首页 >为什么圈阿凡达不能被识别为领导:在ListTile中？

问为什么圈阿凡达不能被识别为领导:在ListTile中？
EN

Stack Overflow用户
提问于 2021-02-05 03:11:04
回答 2查看 1.9K关注 0票数 0

当前正在尝试调试在将项添加到购物车并导航到应该显示购物车项的购物车时发生的错误。

将项目添加到购物车中的功能。仅当项添加到购物车时引发错误。构建不会崩溃。

错误位于cart项小部件中。cart_item.dart嵌套在cart_screen.dart中。

当我在leading:中被识别为ListTile时，我已经能够诊断出这个错误被特别地绑定到圆环阿凡达小部件上。当其他小部件(即文本)被标识为leading:时，不会发生错误。为什么环阿凡达不能在leading:中被识别为ListTile？

错误：

代码语言：javascript
复制
[38;5;248m════════ Exception caught by rendering library ═════════════════════════════════[39;49m
[38;5;244mThe following assertion was thrown during performLayout():[39;49m
Leading widget consumes entire tile width. Please use a sized widget, or consider replacing ListTile with a custom widget (see https://api.flutter.dev/flutter/material/ListTile-class.html#material.ListTile.4)
'package:flutter/src/material/list_tile.dart':
Failed assertion: line 1547 pos 7: 'tileWidth != leadingSize.width'


[38;5;248mEither the assertion indicates an error in the framework itself, or we should provide substantially more information in this error message to help you determine and fix the underlying cause.
In either case, please report this assertion by filing a bug on GitHub:
  https://github.com/flutter/flutter/issues/new?template=BUG.md
[39;49m

[38;5;244mThe relevant error-causing widget was[39;49m
[38;5;248mListTile[39;49m
 lib\widgets\cart_item.dart
[38;5;244mWhen the exception was thrown, this was the stack[39;49m
[38;5;244m#2      _RenderListTile.performLayout[39;49m
 package:flutter/…/material/list_tile.dart
[38;5;244m#3      RenderObject.layout[39;49m
 package:flutter/…/rendering/object.dart
[38;5;244m#4      RenderPadding.performLayout[39;49m
 package:flutter/…/rendering/shifted_box.dart
[38;5;244m#5      RenderObject.layout[39;49m
 package:flutter/…/rendering/object.dart
[38;5;244m#6      RenderProxyBoxMixin.performLayout[39;49m
 package:flutter/…/rendering/proxy_box.dart
[38;5;244m...[39;49m
[38;5;244mThe following RenderObject was being processed when the exception was fired: _RenderListTile#414b8 relayoutBoundary=up38 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE[39;49m
[38;5;244mRenderObject: _RenderListTile#414b8 relayoutBoundary=up38 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE[39;49m
    [38;5;244mparentData: offset=Offset(0.0, 0.0) (can use size)[39;49m
    [38;5;244mconstraints: BoxConstraints(w=11.2, 0.0<=h<=Infinity)[39;49m
    [38;5;244msize: MISSING[39;49m
    [38;5;244mleading: RenderConstrainedBox#0efc0 relayoutBoundary=up39 NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE[39;49m
        [38;5;244mparentData: offset=Offset(0.0, 0.0) (can use size)[39;49m
        [38;5;244mconstraints: BoxConstraints(0.0<=w<=11.2, 0.0<=h<=56.0)[39;49m
        [38;5;244msize: Size(11.2, 40.0)[39;49m
        [38;5;244madditionalConstraints: BoxConstraints(w=40.0, h=40.0)[39;49m
        [38;5;244mchild: RenderDecoratedBox#c9777 NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE[39;49m
            [38;5;244mparentData: <none> (can use size)[39;49m
            [38;5;244mconstraints: BoxConstraints(w=11.2, h=40.0)[39;49m
            [38;5;244msize: Size(11.2, 40.0)[39;49m
            [38;5;244mdecoration: BoxDecoration[39;49m
                [38;5;244mcolor: Color(0xff1976d2)[39;49m
                [38;5;244mshape: circle[39;49m
            [38;5;244mconfiguration: ImageConfiguration(bundle: PlatformAssetBundle#ed2ae(), devicePixelRatio: 3.5, locale: en_US, textDirection: TextDirection.ltr, platform: android)[39;49m
            [38;5;244mchild: RenderPositionedBox#1179f NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE[39;49m
                [38;5;244mparentData: <none> (can use size)[39;49m
                [38;5;244mconstraints: BoxConstraints(w=11.2, h=40.0)[39;49m
                [38;5;244msize: Size(11.2, 40.0)[39;49m
                [38;5;244malignment: center[39;49m
                [38;5;244mtextDirection: ltr[39;49m
                [38;5;244mwidthFactor: expand[39;49m
                [38;5;244mheightFactor: expand[39;49m
                [38;5;244mchild: RenderParagraph#1a8e3 relayoutBoundary=up1 NEEDS-PAINT[39;49m
                    [38;5;244mparentData: offset=Offset(0.1, 0.0) (can use size)[39;49m
                    [38;5;244mconstraints: BoxConstraints(0.0<=w<=11.2, 0.0<=h<=40.0)[39;49m
                    [38;5;244msize: Size(11.0, 40.0)[39;49m
                    [38;5;244mtextAlign: start[39;49m
                    [38;5;244mtextDirection: ltr[39;49m
                    [38;5;244msoftWrap: wrapping at box width[39;49m
                    [38;5;244moverflow: clip[39;49m
                    [38;5;244mlocale: en_US[39;49m
                    [38;5;244mmaxLines: unlimited[39;49m
    [38;5;244mtitle: RenderParagraph#8f830 NEEDS-LAYOUT NEEDS-PAINT[39;49m
        [38;5;244mparentData: offset=Offset(0.0, 0.0)[39;49m
        [38;5;244mconstraints: MISSING[39;49m
        [38;5;244msize: MISSING[39;49m
        [38;5;244mtextAlign: start[39;49m
        [38;5;244mtextDirection: ltr[39;49m
        [38;5;244msoftWrap: wrapping at box width[39;49m
        [38;5;244moverflow: clip[39;49m
        [38;5;244mlocale: en_US[39;49m
        [38;5;244mmaxLines: unlimited[39;49m
        [38;5;244mtext: TextSpan[39;49m
            [38;5;244mdebugLabel: ((englishLike subhead 2014).merge((blackMountainView subtitle1).apply)).copyWith[39;49m
            [38;5;244minherit: false[39;49m
            [38;5;244mcolor: Color(0xdd000000)[39;49m
            [38;5;244mfamily: Lato[39;49m
            [38;5;244msize: 16.0[39;49m
            [38;5;244mweight: 400[39;49m
            [38;5;244mbaseline: alphabetic[39;49m
            [38;5;244mdecoration: TextDecoration.none[39;49m
            [38;5;244m"Yellow Scarf"[39;49m
    [38;5;244msubtitle: RenderParagraph#efae3 NEEDS-LAYOUT NEEDS-PAINT[39;49m
        [38;5;244mparentData: offset=Offset(0.0, 0.0)[39;49m
        [38;5;244mconstraints: MISSING[39;49m
        [38;5;244msize: MISSING[39;49m
        [38;5;244mtextAlign: start[39;49m
        [38;5;244mtextDirection: ltr[39;49m
        [38;5;244msoftWrap: wrapping at box width[39;49m
        [38;5;244moverflow: clip[39;49m
        [38;5;244mlocale: en_US[39;49m
        [38;5;244mmaxLines: unlimited[39;49m
        [38;5;244mtext: TextSpan[39;49m
            [38;5;244mdebugLabel: ((englishLike body1 2014).merge((blackMountainView bodyText2).apply)).copyWith[39;49m
            [38;5;244minherit: false[39;49m
            [38;5;244mcolor: Color(0x8a000000)[39;49m
            [38;5;244mfamily: Lato[39;49m
            [38;5;244msize: 14.0[39;49m
            [38;5;244mweight: 400[39;49m
            [38;5;244mbaseline: alphabetic[39;49m
            [38;5;244mdecoration: TextDecoration.none[39;49m
            [38;5;244m"x 1"[39;49m
    [38;5;244mtrailing: RenderParagraph#53ad3 relayoutBoundary=up39 NEEDS-PAINT[39;49m
        [38;5;244mparentData: offset=Offset(0.0, 0.0) (can use size)[39;49m
        [38;5;244mconstraints: BoxConstraints(0.0<=w<=11.2, 0.0<=h<=56.0)[39;49m
        [38;5;244msize: Size(11.0, 56.0)[39;49m
        [38;5;244mtextAlign: start[39;49m
        [38;5;244mtextDirection: ltr[39;49m
        [38;5;244msoftWrap: wrapping at box width[39;49m
        [38;5;244moverflow: clip[39;49m
        [38;5;244mlocale: en_US[39;49m
        [38;5;244mmaxLines: unlimited[39;49m
        [38;5;244mtext: TextSpan[39;49m
            [38;5;244mdebugLabel: (englishLike body1 2014).merge((blackMountainView bodyText2).apply)[39;49m
            [38;5;244minherit: false[39;49m
            [38;5;244mcolor: Color(0xdd000000)[39;49m
            [38;5;244mfamily: Lato[39;49m
            [38;5;244msize: 14.0[39;49m
            [38;5;244mweight: 400[39;49m
            [38;5;244mbaseline: alphabetic[39;49m
            [38;5;244mdecoration: TextDecoration.none[39;49m
            [38;5;244m"$19.99"[39;49m
[38;5;248m════════════════════════════════════════════════════════════════════════════════[39;49m

[38;5;248m════════ Exception caught by rendering library ═════════════════════════════════[39;49m
RenderBox was not laid out: _RenderListTile#414b8 relayoutBoundary=up38 NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
'package:flutter/src/rendering/box.dart':
Failed assertion: line 1785 pos 12: 'hasSize'

[38;5;244mThe relevant error-causing widget was[39;49m
[38;5;248mListTile[39;49m
 lib\widgets\cart_item.dart
[38;5;248m════════════════════════════════════════════════════════════════════════════════[39;49m

...

继续在整个剩余小部件树中抛出错误。

错误的根发生在这里- cart_item.dart：(忽略提供程序包)

代码语言：javascript
复制
import 'package:flutter/material.dart';
// import 'package:provider/provider.dart';

// import '../models/product_model.dart';
// import 'product_item.dart';

class CartItem extends StatelessWidget {
  CartItem({this.id, this.price, this.quantity, this.title});
  final String id;
  final double price;
  final int quantity;
  final String title;

  @override
  Widget build(BuildContext context) {
    // final product = Provider.of<Product>(context, listen: false);
    return Card(
      margin: EdgeInsets.symmetric(
        vertical: 15,
        horizontal: 4,
      ),
      child: Padding(
        padding: const EdgeInsets.all(8.0),
        child: ListTile(
          leading: CircleAvatar(
            child: Text('\$$price'),
          ),
          //Image.network(product.imageURL),
          title: Text(title),
          subtitle: Text('x $quantity'),
          trailing: Text('\$$price'),
        ),
      ),
    );
  }
}

供参考- cart_screen.dart：

代码语言：javascript
复制
import 'package:flutter/material.dart';
import 'package:provider/provider.dart';

import '../models/cart.dart' show Cart;

import '../widgets/cart_item.dart';

class CartScreen extends StatelessWidget {
  static const routeName = '/cart';
  @override
  Widget build(BuildContext context) {
    final cart = Provider.of<Cart>(context);
    return Scaffold(
      appBar: AppBar(
        title: Text('Your Cart'),
      ),
      body: Column(
        // mainAxisAlignment: MainAxisAlignment.spaceEvenly,
        children: <Widget>[
          Card(
            margin: EdgeInsets.all(15.0),
            child: Padding(
              padding: const EdgeInsets.all(8.0),
              child: Row(
                mainAxisAlignment: MainAxisAlignment.spaceBetween,
                children: <Widget>[
                  Text('Total',
                      style: TextStyle(
                        fontSize: 20,
                      )),
                  Spacer(),
                  Chip(
                    label: Text('\$${cart.totalAmount}'),
                  ),
                  FlatButton(
                    child: Text('order now'.toUpperCase()),
                    textColor: Theme.of(context).primaryColor,
                    onPressed: () {},
                  ),
                  SizedBox(
                    height: 10,
                  ),
                  Expanded(
                    child: ListView.builder(
                      shrinkWrap: true,
                      itemCount: cart.items.length,
                      itemBuilder: (ctx, index) => CartItem(
                          id: cart.items.values.toList()[index].id,
                          price: cart.items.values.toList()[index].price,
                          quantity: cart.items.values.toList()[index].quantity,
                          title: cart.items.values.toList()[index].title),
                    ),
                  ),
                ],
              ),
            ),
          ),
        ],
      ),
    );
  }
}
flutter
listview
dart
widget
flutter-layout
EN

回答 2

Stack Overflow用户

回答已采纳

发布于 2021-02-06 15:59:44

它没有绑定到ListTile中的cart_item中的前导参数，这是错误指示我的。

这是cart_screen中的一个呈现问题。ListView.builder需要发生在Card小部件之外。下面是我如何修复代码：

cart_item中的代码没有改变。

Cart_screen中更新的代码：

代码语言：javascript
复制
class CartScreen extends StatelessWidget {
  static const routeName = '/cart';
  @override
  Widget build(BuildContext context) {
    final cart = Provider.of<Cart>(context);
    return Scaffold(
      appBar: AppBar(
        title: Text('Your Cart'),
      ),
      body: Column(
        // mainAxisAlignment: MainAxisAlignment.spaceEvenly,
        children: <Widget>[
          Card(
            margin: EdgeInsets.all(15.0),
            child: Padding(
              padding: const EdgeInsets.all(8.0),
              child: Row(
                mainAxisAlignment: MainAxisAlignment.spaceBetween,
                children: <Widget>[
                  Text('Total',
                      style: TextStyle(
                        fontSize: 20,
                      )),
                  Spacer(),
                  Chip(
                    label: Text('\$${cart.totalAmount}'),
                  ),
                  FlatButton(
                    child: Text('order now'.toUpperCase()),
                    textColor: Theme.of(context).primaryColor,
                    onPressed: () {},
                  ),
                ],
              ),
            ),
          ),
          SizedBox(
            height: 10,
          ),
          Expanded(
            child: ListView.builder(
              shrinkWrap: true,
              itemCount: cart.items.length,
              itemBuilder: (ctx, index) => CartItem(
                  id: cart.items.values.toList()[index].id,
                  price: cart.items.values.toList()[index].price,
                  quantity: cart.items.values.toList()[index].quantity,
                  title: cart.items.values.toList()[index].title),
            ),
          ),
        ],
      ),
    );
  }
}
票数 1
EN

Stack Overflow用户

发布于 2021-02-05 03:28:14

代码语言：javascript
复制
class CartItem extends StatelessWidget {
  CartItem({this.id, this.price, this.quantity, this.title});
  final String id;
  final double price;
  final int quantity;
  final String title;

  @override
  Widget build(BuildContext context) {
    // final product = Provider.of<Product>(context, listen: false);
    return Card(
      margin: EdgeInsets.symmetric(
        vertical: 15,
        horizontal: 4,
      ),
      child: Padding(
        padding: const EdgeInsets.all(8.0),
        child: ListTile(
          leading: CircleAvatar(
            child: Text('\$$price'),
          ),
          //Image.network(product.imageURL),
          title: Text(title),
          subtitle: Text('x $quantity'),
          trailing: Text('\$$price'),
        ),
      ),
    );
  }
}

class CartScreen extends StatelessWidget {
  static const routeName = '/cart';
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Your Cart'),
      ),
      body: Column(
        // mainAxisAlignment: MainAxisAlignment.spaceEvenly,
        children: <Widget>[
          Card(
            margin: EdgeInsets.all(15.0),
            child: Padding(
              padding: const EdgeInsets.all(8.0),
              child: Row(
                mainAxisAlignment: MainAxisAlignment.spaceBetween,
                children: <Widget>[
                  Text('Total',
                      style: TextStyle(
                        fontSize: 20,
                      )),
                  Spacer(),
                  Chip(
                    label: Text('\$${50}'),
                  ),
                  FlatButton(
                    child: Text('order now'.toUpperCase()),
                    textColor: Theme.of(context).primaryColor,
                    onPressed: () {},
                  ),
                  SizedBox(
                    height: 10,
                  ),
                  Expanded(
                    child: ListView.builder(
                      shrinkWrap: true,
                      itemCount: 3,
                      itemBuilder: (ctx, index) => CartItem(
                          id: index.toString(),
                          price: index.toDouble(),
                          quantity: index,
                          title: index.toString()),
                    ),
                  ),
                ],
              ),
            ),
          ),
        ],
      ),
    );
  }
}

我没有从你的代码中得到任何问题，请检查一次

票数 0
EN
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：

https://stackoverflow.com/questions/66057044

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