不能将参数类型“Widget Function(Categoria)”分配给参数类型“dynamic Function(Child)” 模型颤振

问题描述

我正在关注这个例子。

https://esflutter.dev/docs/catalog/samples/expansion-tile-sample

使类别中的多级可扩展。我有最多 3 个类别的树。

但它给了我这个错误：我把它放在图像中，所以可以看到哪个部分标记了错误：

由于我比较新，我已经尝试解决它好几天了，但我没有意识到它可能是，我也将我的模型留在下面，因为我认为存在错误，也许还有其他方法。地图？或者我没有意识到解决方案，请如果有人可以帮助我。

// To parse this JSON data,do
//
//     final categorias = categoriasFromJson(jsonString);

import 'dart:convert';

Categorias categoriasFromJson(String str) => Categorias.fromJson(json.decode(str));

String categoriasToJson(Categorias data) => json.encode(data.toJson());

class Categorias {
    Categorias({
        this.res,this.id,this.empresa,this.idioma,this.categorias,});

    int res;
    int id;
    int empresa;
    String idioma;
    List<Categoria> categorias;

    factory Categorias.fromJson(Map<String,dynamic> json) => Categorias(
        res: json["res"],id: json["id"],empresa: json["empresa"],idioma: json["idioma"],categorias: List<Categoria>.from(json["categorias"].map((x) => Categoria.fromJson(x))),);

    Map<String,dynamic> toJson() => {
        "res": res,"id": id,"empresa": empresa,"idioma": idioma,"categorias": List<dynamic>.from(categorias.map((x) => x.toJson())),};
}

class Child {
    Child({
        this.id,this.name,this.img,this.titulo,this.children,this.baos,});

    int id;
    String name;
    String img;
    int titulo;
    List<Categoria> children;
    String baos;

    factory Child.fromJson(Map<String,dynamic> json) => Child(
        id: json["id"],name: json["name"] == null ? null : json["name"],img: json["img"],titulo: json["titulo"],children: json["children"] == null ? null : List<Categoria>.from(json["children"].map((x) => Categoria.fromJson(x))),baos: json["Baños"] == null ? null : json["Baños"],dynamic> toJson() => {
        "id": id,"name": name == null ? null : name,"img": imgValues.reverse[img],"titulo": titulo,"children": children == null ? null : List<dynamic>.from(children.map((x) => x.toJson())),"Baños": baos == null ? null : baos,};
}

class Categoria {
    Categoria({
        this.id,});

    int id;
    String name;
    String img;
    int titulo;
    List<Child> children;

    factory Categoria.fromJson(Map<String,dynamic> json) => Categoria(
        id: json["id"],name: json["name"],children: json["children"] == null ? null : List<Child>.from(json["children"].map((x) => Child.fromJson(x))),"name": name,};
}

enum Img { FOTOSCIRCULOS_INSECTICIDA_PNG,EMPTY }

final imgValues = EnumValues({
    "": Img.EMPTY,"fotoscirculos/insecticida.png": Img.FOTOSCIRCULOS_INSECTICIDA_PNG
});

class EnumValues<T> {
    Map<String,T> map;
    Map<T,String> reverseMap;

    EnumValues(this.map);

    Map<T,String> get reverse {
        if (reverseMap == null) {
            reverseMap = map.map((k,v) => new MapEntry(v,k));
        }
        return reverseMap;
    }
}

EntryItem 类：

class BuyView extends StatefulWidget {
  final List<Categoria> categorias;

  const BuyView({Key key,this.categorias}) : super(key: key);

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

class _BuyViewState extends State<BuyView> {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: const Text('ExpansionTile'),),body: ListView.builder(
          itemBuilder: (BuildContext context,int index) =>
              EntryItem(widget.categorias[index]),itemCount: widget.categorias.length,);
  }
}
// displays one Entry. If the entry has children then it's displayed
// with an ExpansionTile.
class EntryItem extends StatelessWidget {
  const EntryItem(this.entry);

  final Categoria entry;

  Widget _buildTiles(Categoria root) {
    if (root.children.isEmpty) return ListTile(title: Text(root.name));
    return ExpansionTile(
      key: PageStorageKey<Categoria>(root),title: Text(root.name),children: root.children.map(_buildTiles).toList(),);
  }

  @override
  Widget build(BuildContext context) {
    return _buildTiles(entry);
  }
}

解决方法

您的 Categoria 和 Child 模型似乎共享几乎所有的属性。问题在于 _buildTiles 需要 Categoria，而 Categoria 的子代是 Child。

如果您合并 Child 和 Categoria 模型，您可以执行以下操作。

class EntryItem extends StatelessWidget {
  const EntryItem(this.entry);

  final Categoria entry;

  Widget _buildTiles(Categoria root) {
    if (root.children.isEmpty) return ListTile(title: Text(root.name));
    return ExpansionTile(
      key: PageStorageKey<Categoria>(root),title: Text(root.name),children: root.children.map((e)=>_buildTiles(e)).toList(),);
  }

  @override
  Widget build(BuildContext context) {
    return _buildTiles(entry);
  }
}

void main() {
  runApp(ExpansionTileSample());
}


class Categoria {
  Categoria({
    this.id,this.name,this.img,this.titulo,this.children,this.baos,});

  int id;
  String name;
  String img;
  int titulo;
  List<Categoria> children;
  String baos;

  factory Categoria.fromJson(Map<String,dynamic> json) => Categoria(
    id: json["id"],name: json["name"] == null ? null : json["name"],img: json["img"],titulo: json["titulo"],children: json["children"] == null ? null : List<Categoria>.from(json["children"].map((x) => Categoria.fromJson(x))),baos: json["Baños"] == null ? null : json["Baños"],);

  Map<String,dynamic> toJson() => {
    "id": id,"name": name == null ? null : name,"img": imgValues.reverse[img],"titulo": titulo,"children": children == null ? null : List<dynamic>.from(children.map((x) => x.toJson())),"Baños": baos == null ? null : baos,};
}



enum Img { FOTOSCIRCULOS_INSECTICIDA_PNG,EMPTY }

final imgValues = EnumValues({
  "": Img.EMPTY,"fotoscirculos/insecticida.png": Img.FOTOSCIRCULOS_INSECTICIDA_PNG
});

class EnumValues<T> {
  Map<String,T> map;
  Map<T,String> reverseMap;

  EnumValues(this.map);

  Map<T,String> get reverse {
    if (reverseMap == null) {
      reverseMap = map.map((k,v) => new MapEntry(v,k));
    }
    return reverseMap;
  }
}