错误：RenderBox 未布局，断言失败：第 1940 行 pos 12：“hasSize”

Question

我无法修复这个错误

RenderBox 未布局：RenderPointerListener#2b92a relayoutBoundary=up9 NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE 'package:flutter/src/rendering/box.dart'：断言失败：第 1940 行 pos 12：'hasSize'。相关的导致错误的小部件是 ->ListView

这是我的所有产品部分。

import 'package:flutter/material.dart';
import 'package:hospital/Drawer/drawercontent.dart';
import 'package:hospital/Product/AllProducts/ProductList/product_list.dart';
import 'package:hospital/Product/AllProducts/carousel.dart';
import 'package:hospital/Product/AllProducts/category.dart';

class AllProducts extends StatefulWidget {
  @override
  _AllProductsState createState() => _AllProductsState();
}

class _AllProductsState extends State<AllProducts> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          backgroundColor: Colors.green,

          title: Text(
            "Product",
            style: TextStyle(fontStyle: FontStyle.italic),
          ),
          actions: [

            IconButton(
              icon: Icon(Icons.person),
              onPressed: () => print("open cart"),
            ),
          ],

        ),
        drawer: Drawer(
          child: DrawerContent(),
        ),
        body: ListView(

          children: [
            Carousel(),
            SizedBox(
              height: 10.0,
            ),

            CategoryPage(),
            SizedBox(
              height: 20.0,
            ),
            ProductList()

          ],
        ));
  }
}

这是我的产品部分

import 'dart:convert';

import 'package:flutter/material.dart';
import 'package:flutter/foundation.dart';
import 'package:hospital/Product/AllProducts/ProductList/network_req.dart';
import 'package:hospital/Product/AllProducts/ProductList/product_model.dart';
import 'package:hospital/constant.dart';
import 'package:http/http.dart' as http;
// import '../../drawercontent.dart';

class ProductList extends StatefulWidget {
  final s_id;

  const ProductList({key, this.s_id}) : super(key: key);
  @override
  _ProductListState createState() => _ProductListState();
}

class _ProductListState extends State<ProductList> {
  @override
  Widget build(BuildContext context) {
    return Container(
      // ignore: missing_required_param
      child: FutureBuilder<List<Model>>(
        // future: NetReq.fetchTeams(),
        future: NetReq.fetchTeams(widget.s_id),

        builder: (context, snapshot) {
          if (snapshot.hasError) {
            return Text("Error ${snapshot.error}");
          } else if (snapshot.hasData) {
            return GridView.count(

                // childAspectRatio: 1.0,
                padding: EdgeInsets.only(left: 20, right: 20),
                crossAxisCount: 2,
                crossAxisSpacing: 18,
                mainAxisSpacing: 18,

                children: snapshot.data.map((team) {
                  return Card(
                    elevation: 3.0,
                    margin: EdgeInsets.all(10.0),
                    shape: RoundedRectangleBorder(

                      borderRadius: BorderRadius.circular(12.0),
                    ),
                    child: Container(
                      width: 150.0,
                      padding: EdgeInsets.all(8.0),

                      child: Column(
                        crossAxisAlignment: CrossAxisAlignment.start,
                        children: <Widget>[
                          Expanded(
                            child: ClipRRect(

                              borderRadius: BorderRadius.circular(14.0),
                              child: Container(
                                decoration: BoxDecoration(
                                  borderRadius: BorderRadius.circular(12.0),
                                  image: DecorationImage(
                                    image: NetworkImage(
                                        "https://5.imimg.com/data5/MR/TK/KJ/SELLER-769696/tulac-granules-500x500.jpeg"),
                                  ),

                                ),
                              ),
                            ),
                          ),
                          SizedBox(height: 12.0),

                          Text(
                              // "Tulac Granules, For Personal, Packaging Size: 90 Gm",
                              team.teamUniqId,
                              overflow: TextOverflow.ellipsis,
                              maxLines: 2,

                              style: kTitleStyle),
                          SizedBox(height: 6.0),
                          Text(
                              // "\u20B9 239/ Box",
                              team.teamType,

                              maxLines: 1,
                              style: kSubTitleStyle),
                        ],
                      ),
                    ),

                  );
                }).toList());
          }
          return Center(
            child: CircularProgressIndicator(),

          );
        },
      ),
    );

  }
}

Answer 1

当 ListView 没有约束高度使其获得无限高度时会发生这种情况，您可以使用两种解决方案来解决此问题

1. 添加shrinkWrap: true作为参数，这将告诉 ListView 使用尽可能小的空间，

2. 用受约束的高度小部件（例如 aSizedBox或 a ）包裹您的 ListView，Container并为其指定高度和宽度，如下所示

       Container(
            height: 50,
            width: 50,
            child: ListView()
              )

希望这能解决你的问题

Answer 2

当 ListView 没有高度限制时，您会遇到这个问题。您可以 ListView用Expanded小部件包装您的。另外，添加shrinkWrap: true为参数。

Expanded(
   child: ListView(
      shrinkWrap: true,
   ),
 )

Answer 3

请添加如下内容GridView shrinkWrap: true：

return GridView.count(
  shrinkWrap: true
   padding: EdgeInsets.only(left: 20, right: 20),
   crossAxisCount: 2,
   crossAxisSpacing: 18,
   mainAxisSpacing: 18,
);