在颤振映射功能在列小部件中不起作用

时间：2021-02-09 22:25:29

标签： flutter dart

我正在尝试在列小部件内动态创建行小部件。我是 flutter 的新手，我尽了最大的努力，但仍然没有解决这个问题。我想请你帮我解决这个问题。我添加了我尝试过的所有东西。非常感谢

我的 Json

{
    "status": true,
    "data": {
        "id": 1,
        "image": "https://img.taste.com.au/fruCLEZM/taste/2019/08/chicken-karahi-153167-2.jpg",
        "calories": 100,
        "ingredients_count": 5,
        "serve": 1,
        "views": 1,
        "time": 1,
        "translate": {
            "post_title": "Chicken Karahi",
            "post_description": "spicy and tasteful chicken karahi."
        },
        "ingredients": [
            {
                "name": "yogurt",
                "quantity": "1 cup",
                "image": "https://www.archanaskitchen.com/images/archanaskitchen/BasicRecipes_HOW_TO/How_To_Make_Fresh_Homemade_Yogurt_Curd_400.jpg"
            },
            {
                "name": "red chilli",
                "quantity": "100 gram",
                "image": "https://ik.imagekit.io/91ubcvvnh3k/tr:w-500/https://www.planetorganic.com//images/products/medium/26148.jpg"
            }
        ]
    }
}

Image for refrence

我面临以下两个错误，

Another exception was thrown: type '(dynamic) => dynamic' is not a subtype of type '(Ingredient) => Widget' of 'f'

和

type 'Container' is not a subtype of type 'List<Widget>'

在我的有状态课程中，我有以下内容

var posts;
bool _load = false;
void initState() {     
  super.initState();
  getRecipeById().then((value) => {
    setState((){
      posts = value;
    })
  });
}

通过这种方法我从 api 获取数据

getRecipeById() async {
      String url = 'http://www.xxxxx.com/xxxxx/in.php';
      Map<String, String> requestHeaders = {
        'Content-type': 'application/json',
        'Accept': '*/*',
      };
      final json = {
        "by_post_id": 'yes',
        "post_id":'${widget.postId}'
      };
      http.Response response = await http.post(url, body: json);
      if(response.statusCode == 200){
        setState(() {
          _load = true;
        });
      }
      var jsonResponse = jsonDecode(response.body);
      posts = RecipeModel.fromJson(jsonResponse['data']);
      return posts;
    }

以下是我的构建小部件

Widget build(BuildContext context) {
  final ingredientsList = Container(
    width: MediaQuery.of(context).size.width,
    padding: EdgeInsets.only(left: 1.0, right: 25.0),
    margin: const EdgeInsets.only(bottom: 20.0),
    child: Container(
      child: Column(
        children: (_load == false) ? Container(child:Text("loading..")) : posts.ingredients.map<Widget>((data) => 
          ingredientsRow(data.name, data.quantity, data.image)
        ).toList(),
      ),
    ),
  );

  return SafeArea(
      top: true,
      child: Scaffold(
      body: Directionality(
        textDirection: TextDirection.ltr,
        child: SingleChildScrollView(
          child: (_load == false) ? Container(
            alignment: Alignment.center,
            child: Text("loading now..")
            ) :
          Column(
            children: <Widget>[
              ingredientsList,

            ],
          ),
        ),
      ),
    )
  );
}

以下是我想在地图中使用的功能

ingredientsRow(name, quantity, image)
    {
      return Row(
        mainAxisAlignment: MainAxisAlignment.start,
        children: [
              Expanded(
                flex: 2, // 20%
                child: Container(
                  alignment: Alignment.center,
                    child: Image.network(image,
                    height: 45,
                    ) 
                ),
              ),
              Expanded(
                flex: 4, // 60%
                child: Container(
                  child:Text(
                    name,
                    style: TextStyle(
                      color: Color(0xff41453c), 
                      fontSize: 15,
                      fontWeight: FontWeight.w400
                    ),
                  )
                ),
              ),
              Expanded(
                flex: 4, // 20%
                child: Container(
                  alignment: Alignment.center,
                  child:Text(
                    quantity,
                    style: TextStyle(
                      color: Color(0xff41453c), 
                      fontSize: 15,
                      fontWeight: FontWeight.w400
                    ),
                  )
                ),
              )
            ],
        );
    }

这是我的数据模型类

class RecipeModel{
  final int id;
  final String image;
  final List<Ingredient> ingredients;

  RecipeModel({this.id, this.image, this.ingredients});

  factory RecipeModel.fromJson(Map<String, dynamic> parsedJson){

    var list = parsedJson['ingredients'] as List;
    print(list.runtimeType);
    List<Ingredient> ingredientsList = list.map((i) => Ingredient.fromJson(i)).toList();
    return RecipeModel(
      id: parsedJson['id'],
      image: parsedJson['image'],
      ingredients: ingredientsList

    );
  }
}

class Ingredient {
  final String name;
  final String quantity;
  final String image;

  Ingredient({this.name, this.quantity, this.image});

  factory Ingredient.fromJson(Map<String, dynamic> parsedJson){
   return Ingredient(
     name:parsedJson['name'],
     quantity:parsedJson['quantity'],
     image:parsedJson['image']
   );
  }
}

1 个答案:

答案 0 :(得分：0)

最好的方法是使用 FutureBuilder。

我检查了您的代码，主要更改了 4 件事：

1- 我在 FutureBuilder 中使用了一种方法，该方法专为此目的而构建。

2- 移除成分列表变量，并将其代码移至名为 _buildIngredientList 且返回类型为 Widget 的函数中。

3- 移除 bool 变量，因为不再需要使用 FutureBuilder。

4- 给成分行函数添加了返回类型“Widget”，否则会抛出类型错误。

查看下面的代码：

import 'package:flutter/material.dart';
import 'dart:convert';

import 'package:stackoverflowsamples/models.dart';

void main() => runApp(
  MaterialApp(home: HomePage(),
    theme: ThemeData.fallback(),
  ),
);
class HomePage extends StatefulWidget {

  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  var posts;
  ///3 - Remove bool

  void initState() {
    super.initState();
    getRecipeById().then((value) => {
      setState((){
        posts = value;
      })
    });
  }

  Widget build(BuildContext context) {
    return SafeArea(
        top: true,
        child: Scaffold(
          body: Directionality(
            textDirection: TextDirection.ltr,
            child: SingleChildScrollView(
              child:
              FutureBuilder( ///1
                future: getRecipeById(),
                builder: (context, snapshot) {
                  if(snapshot.connectionState == ConnectionState.done) {
                    return Column(
                      children: <Widget>[
                        _buildIngredientList(),
                      ],
                    );
                  } else {
                    return Container(
                        alignment: Alignment.center,
                        child: Text("loading now..")
                    );
                  }
                }
              ),
            ),
          ),
        )
    );
  }

  Widget _buildIngredientList() { ///2
    return Container(
      width: MediaQuery.of(context).size.width,
      padding: EdgeInsets.only(left: 1.0, right: 25.0),
      margin: const EdgeInsets.only(bottom: 20.0),
      child: Container(
        child: Column(
          children: posts.ingredients.map<Widget>((data) =>
              ingredientsRow(data.name, data.quantity, data.image)
          ).toList(),
        ),
      ),
    );
  }
  ///4
  Widget ingredientsRow(name, quantity, image) {
    return Row(
      mainAxisAlignment: MainAxisAlignment.start,
      children: [
        Expanded(
          flex: 2, // 20%
          child: Container(
              alignment: Alignment.center,
              child: Image.network(image,
                height: 45,
              )
          ),
        ),
        Expanded(
          flex: 4, // 60%
          child: Container(
              child:Text(
                name,
                style: TextStyle(
                    color: Color(0xff41453c),
                    fontSize: 15,
                    fontWeight: FontWeight.w400
                ),
              )
          ),
        ),
        Expanded(
          flex: 4, // 20%
          child: Container(
              alignment: Alignment.center,
              child:Text(
                quantity,
                style: TextStyle(
                    color: Color(0xff41453c),
                    fontSize: 15,
                    fontWeight: FontWeight.w400
                ),
              )
          ),
        )
      ],
    );
  }

  getRecipeById() async {
    ///I've pasted the json as literal here because otherwise I couldn't make it run on my side.
    var jsonResponse = jsonDecode('''{
    "status": true,
    "data": {
        "id": 1,
        "image": "https://img.taste.com.au/fruCLEZM/taste/2019/08/chicken-karahi-153167-2.jpg",
        "calories": 100,
        "ingredients_count": 5,
        "serve": 1,
        "views": 1,
        "time": 1,
        "translate": {
            "post_title": "Chicken Karahi",
            "post_description": "spicy and tasteful chicken karahi."
        },
        "ingredients": [
            {
                "name": "yogurt",
                "quantity": "1 cup",
                "image": "https://www.archanaskitchen.com/images/archanaskitchen/BasicRecipes_HOW_TO/How_To_Make_Fresh_Homemade_Yogurt_Curd_400.jpg"
            },
            {
                "name": "red chilli",
                "quantity": "100 gram",
                "image": "https://ik.imagekit.io/91ubcvvnh3k/tr:w-500/https://www.planetorganic.com//images/products/medium/26148.jpg"
            }
        ]
    }
}''');
    posts = RecipeModel.fromJson(jsonResponse['data']);
    return posts;
  }
}
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