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如何使用flutter null安全获取json数组？

[英]How to fetch json Array with flutter null safety?

 原文  2021-09-08 08:27:37  0   1    flutter/ listview/ dart-null-safety

问题描述

我想在列表视图中显示餐厅详细信息。 但是，即使我得到 json 响应正文，我也会不断收到称为“空检查运算符用于空值”值的错误。 任何人都可以帮助我知道我到底哪里出错了？ 在 lisview 构建器中显示错误。 我想在列表视图中显示 json 数据。

要获取的 Json

[{
    "_id": "5cd140215dcd1c1cf4971f72",
    "Name": "Gin Menu",
    "IsMain": false,
    "Schedule": [],
    "Image": {
        "ID": "5c1cd81db5cf1707ac419be1",
        "Name": "Gin Menu Banner.jpg",
        "AltText": "Gin Menu",
        "Url": "/local-media/5c1cd81db5cf1707ac419be1/Gin Menu Bannermin.jpg",
        "FileSize": 133268,
        "IsImage": true,
        "Sizes": [{
            "Name": "thumb",
            "Height": 72,
            "Width": 150,
            "Url": "/local-media/5c1cd81db5cf1707ac419be1/size/thumb-1545394278352.jpg"
        }]
    },
    "FeatureBoxImage": {
        "ID": "5c1cd813b5cf1707ac419be0",
        "Name": "Gin Menu Small.jpg",
        "AltText": "Gin Menu",
        "Url": "/local-media/5c1cd813b5cf1707ac419be0/Gin Menu Smallmin.jpg",
        "FileSize": 52722,
        "IsImage": true,
        "Sizes": [{
            "Name": "thumb",
            "Height": 112,
            "Width": 150,
            "Url": "/local-media/5c1cd813b5cf1707ac419be0/size/thumb-1545394278530.jpg"
        }]
    },
    "ModifiedDate": "2019-06-26T06:42:44.754Z"
}, {
    "_id": "5c7d0dcb1ce9a723b46207d8",
    "Name": "The Brigadoon",
    "IsMain": false,
    "Schedule": [],
    "Image": {
        "ID": "5c1cc449b5cf1707ac419bda",
        "Name": "Brigadoon Banner.jpg",
        "AltText": "Black Watch Brigadoon",
        "Url": "/local-media/5c1cc449b5cf1707ac419bda/Brigadoon Bannermin.jpg",
        "FileSize": 111161,
        "IsImage": true,
        "Sizes": [{
            "Name": "thumb",
            "Height": 72,
            "Width": 150,
            "Url": "/local-media/5c1cc449b5cf1707ac419bda/size/thumb-1545389147819.jpg"
        }]
    },
    "FeatureBoxImage": {
        "ID": "5c1cc3ceb5cf1707ac419bd9",
        "Name": "Brigadoon Small.jpg",
        "AltText": "Black Watch Brigadoon",
        "Url": "/local-media/5c1cc3ceb5cf1707ac419bd9/Brigadoon Smallmin.jpg",
        "FileSize": 57222,
        "IsImage": true,
        "Sizes": [{
            "Name": "thumb",
            "Height": 112,
            "Width": 150,
            "Url": "/local-media/5c1cc3ceb5cf1707ac419bd9/size/thumb-1545389035679.jpg"
        }]
    },
    "ModifiedDate": "2019-06-26T06:42:44.753Z"
}, {
    "_id": "5c4711bd9e7cfb1ea4885404",
    "Name": "Little Skippers",
    "IsMain": false,
    "Schedule": [],
    "Image": {
        "ID": "5c24a847df2455109c8a0e84",
        "Name": "Little Skippers Banner.jpg",
        "AltText": "Little Skippers",
        "Url": "/local-media/5c24a847df2455109c8a0e84/Little Skippers Bannermin.jpg",
        "FileSize": 72479,
        "IsImage": true,
        "Sizes": [{
            "Name": "thumb",
            "Height": 72,
            "Width": 150,
            "Url": "/local-media/5c24a847df2455109c8a0e84/size/thumb-1545907409393.jpg"
        }]
    },
    "FeatureBoxImage": {
        "ID": "5c24a846df2455109c8a0e83",
        "Name": "Little Skippers Small.jpg",
        "AltText": "Little Skippers",
        "Url": "/local-media/5c24a846df2455109c8a0e83/Little Skippers Smallmin.jpg",
        "FileSize": 26117,
        "IsImage": true,
        "Sizes": [{
            "Name": "thumb",
            "Height": 112,
            "Width": 150,
            "Url": "/local-media/5c24a846df2455109c8a0e83/size/thumb-1545907409398.jpg"
        }]
    },
    "ModifiedDate": "2019-06-26T06:42:44.753Z"
}, {
    "_id": "5c4711b89e7cfb1ea4885403",
    "Name": "Speciality Drinks",
    "IsMain": false,
    "Schedule": [],
    "Image": {
        "ID": "5c24a846df2455109c8a0e80",
        "Name": "Speciality Drinks Banner.jpg",
        "AltText": "Speciality Drinks",
        "Url": "/local-media/5c24a846df2455109c8a0e80/Speciality Drinks Bannermin.jpg",
        "FileSize": 69032,
        "IsImage": true,
        "Sizes": [{
            "Name": "thumb",
            "Height": 72,
            "Width": 150,
            "Url": "/local-media/5c24a846df2455109c8a0e80/size/thumb-1545907409390.jpg"
        }]
    },
    "FeatureBoxImage": {
        "ID": "5c24a845df2455109c8a0e7f",
        "Name": "Speciality Drinks Small.jpg",
        "AltText": "Speciality Drinks",
        "Url": "/local-media/5c24a845df2455109c8a0e7f/Speciality Drinks Smallmin.jpg",
        "FileSize": 35169,
        "IsImage": true,
        "Sizes": [{
            "Name": "thumb",
            "Height": 112,
            "Width": 150,
            "Url": "/local-media/5c24a845df2455109c8a0e7f/size/thumb-1545907409324.jpg"
        }]
    },
    "ModifiedDate": "2019-06-26T06:42:44.753Z"
}, {
    "_id": "5c4711ae59ef2019802fc5f7",
    "Name": "Traditional Afternoon Tea",
    "IsMain": false,
    "Schedule": [],
    "Image": {
        "ID": "5c24a8459b560023f4f1253b",
        "Name": "Traditional Afternoon Tea Banner.jpg",
        "AltText": "Traditional Afternoon Tea",
        "Url": "/local-media/5c24a8459b560023f4f1253b/TAT Bannermin.jpg",
        "FileSize": 73732,
        "IsImage": true,
        "Sizes": [{
            "Name": "thumb",
            "Height": 72,
            "Width": 150,
            "Url": "/local-media/5c24a8459b560023f4f1253b/size/thumb-1545907409389.jpg"
        }]
    },
    "FeatureBoxImage": {
        "ID": "5c24a845df2455109c8a0e7e",
        "Name": "Traditional Afternoon Tea Small.jpg",
        "AltText": "Traditional Afternoon Tea",
        "Url": "/local-media/5c24a845df2455109c8a0e7e/TAT Smallmin.jpg",
        "FileSize": 41278,
        "IsImage": true,
        "Sizes": [{
            "Name": "thumb",
            "Height": 112,
            "Width": 150,
            "Url": "/local-media/5c24a845df2455109c8a0e7e/size/thumb-1545907409405.jpg"
        }]
    },
    "ModifiedDate": "2019-06-26T06:42:44.753Z"
}, {
    "_id": "5c4711a859ef2019802fc5f6",
    "Name": "The Bookmark Café",
    "IsMain": false,
    "Schedule": [],
    "Image": {
        "ID": "5c24a845df2455109c8a0e7d",
        "Name": "The Bookmark Cafe Banner.jpg",
        "AltText": "The Bookmark Cafe",
        "Url": "/local-media/5c24a845df2455109c8a0e7d/The Bookmark Cafe Bannermin.jpg",
        "FileSize": 79988,
        "IsImage": true,
        "Sizes": [{
            "Name": "thumb",
            "Height": 72,
            "Width": 150,
            "Url": "/local-media/5c24a845df2455109c8a0e7d/size/thumb-1545907409388.jpg"
        }]
    },
    "FeatureBoxImage": {
        "ID": "5c24a8459b560023f4f1253a",
        "Name": "The Bookmark Cafe Small.jpg",
        "AltText": "The Bookmark Cafe",
        "Url": "/local-media/5c24a8459b560023f4f1253a/The Bookmark Cafe Smallmin.jpg",
        "FileSize": 42153,
        "IsImage": true,
        "Sizes": [{
            "Name": "thumb",
            "Height": 112,
            "Width": 150,
            "Url": "/local-media/5c24a8459b560023f4f1253a/size/thumb-1545907409398.jpg"
        }]
    },
    "ModifiedDate": "2019-06-26T06:42:44.753Z"
}, {
    "_id": "5c47119d59ef2019802fc5f5",
    "Name": "All Inclusive",
    "IsMain": false,
    "Schedule": [],
    "Image": {
        "ID": "5c24acf69b560023f4f12543",
        "Name": "All Inclusive Banner.jpg",
        "AltText": "All Inclusive",
        "Url": "/local-media/5c24acf69b560023f4f12543/All Inclusive Bannermin.jpg",
        "FileSize": 78711,
        "IsImage": true,
        "Sizes": [{
            "Name": "thumb",
            "Height": 72,
            "Width": 150,
            "Url": "/local-media/5c24acf69b560023f4f12543/size/thumb-1545907482729.jpg"
        }]
    },
    "FeatureBoxImage": {
        "ID": "5c24acf6df2455109c8a0e8c",
        "Name": "All Inclusive Small.jpg",
        "AltText": "All Inclusive",
        "Url": "/local-media/5c24acf6df2455109c8a0e8c/All Inclusive Smallmin.jpg",
        "FileSize": 41256,
        "IsImage": true,
        "Sizes": [{
            "Name": "thumb",
            "Height": 112,
            "Width": 150,
            "Url": "/local-media/5c24acf6df2455109c8a0e8c/size/thumb-1545907482803.jpg"
        }]
    },
    "ModifiedDate": "2019-06-26T06:42:44.752Z"
}, {
    "_id": "5c4711919e7cfb1ea48853ff",
    "Name": "Bar Menu",
    "IsMain": false,
    "Schedule": [],
    "Image": {
        "ID": "5c24a847df2455109c8a0e85",
        "Name": "Bar Menu Banner.jpg",
        "AltText": "Bar Menu",
        "Url": "/local-media/5c24a847df2455109c8a0e85/Bar Menu Bannermin.jpg",
        "FileSize": 95343,
        "IsImage": true,
        "Sizes": [{
            "Name": "thumb",
            "Height": 72,
            "Width": 150,
            "Url": "/local-media/5c24a847df2455109c8a0e85/size/thumb-1545907409106.jpg"
        }]
    },
    "FeatureBoxImage": {
        "ID": "5c24a8479b560023f4f1253c",
        "Name": "Bar Menu Small.jpg",
        "AltText": "Bar Menu",
        "Url": "/local-media/5c24a8479b560023f4f1253c/Bar Menu Smallmin.jpg",
        "FileSize": 49277,
        "IsImage": true,
        "Sizes": [{
            "Name": "thumb",
            "Height": 112,
            "Width": 150,
            "Url": "/local-media/5c24a8479b560023f4f1253c/size/thumb-1545907409139.jpg"
        }]
    },
    "ModifiedDate": "2019-06-26T06:42:44.752Z"
}, {
    "_id": "5c4711799e7cfb1ea48853fd",
    "Name": "Wine Menu",
    "IsMain": false,
    "Schedule": [],
    "Image": {
        "ID": "5c1cd45f8ad49c181c12f02c",
        "Name": "Wine Banner.jpg",
        "AltText": "Wine Menu",
        "Url": "/local-media/5c1cd45f8ad49c181c12f02c/Wine Bannermin.jpg",
        "FileSize": 67251,
        "IsImage": true,
        "Sizes": [{
            "Name": "thumb",
            "Height": 72,
            "Width": 150,
            "Url": "/local-media/5c1cd45f8ad49c181c12f02c/size/thumb-1545394278503.jpg"
        }]
    },
    "FeatureBoxImage": {
        "ID": "5c1cd45e8ad49c181c12f02b",
        "Name": "Wine Small.jpg",
        "AltText": "Wine Menu",
        "Url": "/local-media/5c1cd45e8ad49c181c12f02b/Wine Smallmin.jpg",
        "FileSize": 33842,
        "IsImage": true,
        "Sizes": [{
            "Name": "thumb",
            "Height": 112,
            "Width": 150,
            "Url": "/local-media/5c1cd45e8ad49c181c12f02b/size/thumb-1545394278527.jpg"
        }]
    },
    "ModifiedDate": "2019-06-26T06:42:44.752Z"
}, {
    "_id": "5c4710e159ef2019802fc5ec",
    "Name": "Room Service",
    "IsMain": false,
    "Schedule": [],
    "Image": {
        "ID": "5c24a846df2455109c8a0e82",
        "Name": "Room Service Banner.jpg",
        "AltText": "Room Service",
        "Url": "/local-media/5c24a846df2455109c8a0e82/Room Service Bannermin.jpg",
        "FileSize": 64807,
        "IsImage": true,
        "Sizes": [{
            "Name": "thumb",
            "Height": 72,
            "Width": 150,
            "Url": "/local-media/5c24a846df2455109c8a0e82/size/thumb-1545907409399.jpg"
        }]
    },
    "FeatureBoxImage": {
        "ID": "5c24a846df2455109c8a0e81",
        "Name": "Room Service Small.jpg",
        "AltText": "Room Service",
        "Url": "/local-media/5c24a846df2455109c8a0e81/Room Service Smallmin.jpg",
        "FileSize": 32031,
        "IsImage": true,
        "Sizes": [{
            "Name": "thumb",
            "Height": 112,
            "Width": 150,
            "Url": "/local-media/5c24a846df2455109c8a0e81/size/thumb-1545907409389.jpg"
        }]
    },
    "ModifiedDate": "2019-06-26T06:42:44.760Z"
}, {
    "_id": "5c47107d59ef2019802fc5e8",
    "Name": "The Oriental Room",
    "IsMain": false,
    "Schedule": [],
    "Image": {
        "ID": "5c1ccbae8ad49c181c12f029",
        "Name": "BW Oriental Room Banner.jpg",
        "AltText": "Black Watch Oriental Room",
        "Url": "/local-media/5c1ccbae8ad49c181c12f029/BW Oriental Room Bannermin.jpg",
        "FileSize": 66118,
        "IsImage": true,
        "Sizes": [{
            "Name": "thumb",
            "Height": 72,
            "Width": 150,
            "Url": "/local-media/5c1ccbae8ad49c181c12f029/size/thumb-1545391203248.jpg"
        }]
    },
    "FeatureBoxImage": {
        "ID": "5c1ccbac8ad49c181c12f028",
        "Name": "BW Oriental Room Small.jpg",
        "AltText": "Black Watch Oriental Room",
        "Url": "/local-media/5c1ccbac8ad49c181c12f028/BW Oriental Room Smallmin.jpg",
        "FileSize": 31755,
        "IsImage": true,
        "Sizes": [{
            "Name": "thumb",
            "Height": 112,
            "Width": 150,
            "Url": "/local-media/5c1ccbac8ad49c181c12f028/size/thumb-1545391203323.jpg"
        }]
    },
    "ModifiedDate": "2019-06-26T06:42:44.752Z"
}, {
    "_id": "5c4710559e7cfb1ea48853ef",
    "Name": "The Poolside",
    "IsMain": false,
    "Schedule": [],
    "Image": {
        "ID": "5c1cc86b8ad49c181c12f026",
        "Name": "BW The Poolside Banner.jpg",
        "AltText": "Black Watch The Poolside",
        "Url": "/local-media/5c1cc86b8ad49c181c12f026/BW The Poolside Bannermin.jpg",
        "FileSize": 123988,
        "IsImage": true,
        "Sizes": [{
            "Name": "thumb",
            "Height": 72,
            "Width": 150,
            "Url": "/local-media/5c1cc86b8ad49c181c12f026/size/thumb-1574182960195.jpg"
        }]
    },
    "FeatureBoxImage": {
        "ID": "5c1cc8f3b5cf1707ac419bdd",
        "Name": "BW The Poolside Small.jpg",
        "AltText": "Black Watch The Poolside",
        "Url": "/local-media/5c1cc8f3b5cf1707ac419bdd/BW The Poolside Smallmin.jpg",
        "FileSize": 56214,
        "IsImage": true,
        "Sizes": [{
            "Name": "thumb",
            "Height": 112,
            "Width": 150,
            "Url": "/local-media/5c1cc8f3b5cf1707ac419bdd/size/thumb-1574182974716.jpg"
        }]
    },
    "ModifiedDate": "2019-06-26T06:42:44.760Z"
}, {
    "_id": "5b890c0a9efdc413a8a693b8",
    "Name": "The Orchid Room",
    "IsMain": false,
    "Schedule": [],
    "Image": {
        "ID": "5c1cc142b5cf1707ac419bd5",
        "Name": "Orchid Room Banner.jpg",
        "AltText": "Black Watch Orchid Room",
        "Url": "/local-media/5c1cc142b5cf1707ac419bd5/Orchid Room Bannermin.jpg",
        "FileSize": 161483,
        "IsImage": true,
        "Sizes": [{
            "Name": "thumb",
            "Height": 72,
            "Width": 150,
            "Url": "/local-media/5c1cc142b5cf1707ac419bd5/size/thumb-1545388412446.jpg"
        }]
    },
    "FeatureBoxImage": {
        "ID": "5c94d99f8492d920e8c4906a",
        "Name": "Orchid Room Small.jpg",
        "AltText": "Orchid Room",
        "Url": "/local-media/5c94d99f8492d920e8c4906a/Orchid Room Smallmin 1.jpg",
        "FileSize": 75348,
        "IsImage": true,
        "Sizes": [{
            "Name": "thumb",
            "Height": 112,
            "Width": 150,
            "Url": "/local-media/5c94d99f8492d920e8c4906a/size/thumb-1553258941876.jpg"
        }]
    },
    "ModifiedDate": "2019-06-26T06:42:44.749Z"
}, {
    "_id": "5b890bee9efdc413a8a693b4",
    "Name": "The Glentanar",
    "IsMain": true,
    "AppOrder": null,
    "Schedule": [],
    "Image": {
        "ID": "5c13799fbd1be61938f2f067",
        "Name": "BWGlentanar.png",
        "AltText": "Black Watch Glentanar Restaurant",
        "Url": "/local-media/5c13799fbd1be61938f2f067/BWGlentanar.png",
        "FileSize": 282390,
        "IsImage": true,
        "Sizes": [{
            "Name": "thumb",
            "Height": 76,
            "Width": 150,
            "Url": "/local-media/5c13799fbd1be61938f2f067/size/thumb-1544780203790.png"
        }]
    },
    "FeatureBoxImage": {
        "ID": "5c137d51bd1be61938f2f070",
        "Name": "BW-Glentanar-Small.png",
        "AltText": "Black Watch Glentanar Restaurant",
        "Url": "/local-media/5c137d51bd1be61938f2f070/BWGlentanarSmall.png",
        "FileSize": 114536,
        "IsImage": true,
        "Sizes": [{
            "Name": "thumb",
            "Height": 112,
            "Width": 150,
            "Url": "/local-media/5c137d51bd1be61938f2f070/size/thumb-1544781157764.png"
        }]
    },
    "ModifiedDate": "2020-01-06T10:27:52.962Z"
}, {
    "_id": "5b890bf69efdc413a8a693b6",
    "Name": "The Black Watch Room",
    "IsMain": false,
    "Schedule": [],
    "Image": {
        "ID": "5c1cc6cbb5cf1707ac419bdb",
        "Name": "Black Watch Room Banner.jpg",
        "AltText": "Black Watch Room",
        "Url": "/local-media/5c1cc6cbb5cf1707ac419bdb/Black Watch Room Bannermin.jpg",
        "FileSize": 101075,
        "IsImage": true,
        "Sizes": [{
            "Name": "thumb",
            "Height": 72,
            "Width": 150,
            "Url": "/local-media/5c1cc6cbb5cf1707ac419bdb/size/thumb-1545390185903.jpg"
        }]
    },
    "FeatureBoxImage": {
        "ID": "5c1cc5128ad49c181c12f024",
        "Name": "Black Watch Room Small.jpg",
        "AltText": "Black Watch Room",
        "Url": "/local-media/5c1cc5128ad49c181c12f024/Black Watch Room Smallmin.jpg",
        "FileSize": 49544,
        "IsImage": true,
        "Sizes": [{
            "Name": "thumb",
            "Height": 112,
            "Width": 150,
            "Url": "/local-media/5c1cc5128ad49c181c12f024/size/thumb-1545390186107.jpg"
        }]
    },
    "ModifiedDate": "2019-06-26T06:42:44.748Z"
}]

我的模型类

import 'dart:convert';

List<RestaurantResponseModel> restaurantResponseModelFromJson(String str) => List<RestaurantResponseModel>.from(json.decode(str).map((x) => RestaurantResponseModel.fromJson(x)));

String restaurantResponseModelToJson(List<RestaurantResponseModel> data) => json.encode(List<dynamic>.from(data.map((x) => x.toJson())));

class RestaurantResponseModel {
  RestaurantResponseModel({
    this.id,
    this.name,
    this.isMain,
    this.schedule,
    this.images,
    this.featureBoxImages,
    this.modifiedDate,
    this.appOrder,
  });

  String? id;
  String? name;
  bool? isMain;
  List<dynamic>? schedule;
  Images? images;
  Images? featureBoxImages;
  DateTime? modifiedDate;
  dynamic? appOrder;

  factory RestaurantResponseModel.fromJson(Map<String, dynamic> json) => RestaurantResponseModel(
    id: json["_id"],
    name: json["Name"],
    isMain: json["IsMain"],
    schedule: List<dynamic>.from(json["Schedule"].map((x) => x)),
    images: Images.fromJson(json["Images"]),
    featureBoxImages: Images.fromJson(json["FeatureBoxImages"]),
    modifiedDate: DateTime.parse(json["ModifiedDate"]),
    appOrder: json["AppOrder"],
  );

  Map<String, dynamic> toJson() => {
    "_id": id,
    "Name": name,
    "IsMain": isMain,
    "Schedule": List<dynamic>.from(schedule!.map((x) => x)),
    "Images": images!.toJson(),
    "FeatureBoxImages": featureBoxImages!.toJson(),
    "ModifiedDate": modifiedDate!.toIso8601String(),
    "AppOrder": appOrder,
  };
}

class Images {
  Images({
    this.id,
    this.name,
    this.altText,
    this.url,
    this.fileSize,
    this.isImages,
    this.sizes,
  });

  String? id;
  String? name;
  String? altText;
  String? url;
  int? fileSize;
  bool? isImages;
  List<Size>? sizes;

  factory Images.fromJson(Map<String, dynamic> json) => Images(
    id: json["ID"],
    name: json["Name"],
    altText: json["AltText"],
    url: json["Url"],
    fileSize: json["FileSize"],
    isImages: json["IsImages"],
    sizes: List<Size>.from(json["Sizes"].map((x) => Size.fromJson(x))),
  );

  Map<String, dynamic> toJson() => {
    "ID": id,
    "Name": name,
    "AltText": altText,
    "Url": url,
    "FileSize": fileSize,
    "IsImages": isImages,
    "Sizes": List<dynamic>.from(sizes!.map((x) => x.toJson())),
  };
}

class Size {
  Size({
    this.name,
    this.height,
    this.width,
    this.url,
  });

  Name? name;
  int? height;
  int? width;
  String? url;

  factory Size.fromJson(Map<String, dynamic> json) => Size(
    name: nameValues.map[json["Name"]],
    height: json["Height"],
    width: json["Width"],
    url: json["Url"],
  );

  Map<String, dynamic> toJson() => {
    "Name": nameValues.reverse[name],
    "Height": height,
    "Width": width,
    "Url": url,
  };
}

enum Name { THUMB }

final nameValues = EnumValues({
  "thumb": Name.THUMB
});

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!;
  }
}

1 个解决方案

解决方案1
 0  2021-10-20 12:18:50

在 null 上使用的 null 检查运算符

这意味着你做了这样的事情：

print(myNullableVariable!);

也就是说，你把一个空变量后跟一个! ，变量为空。

这是你每次使用的时候!

"Images": images!.toJson(),
"FeatureBoxImages": featureBoxImages!.toJson(),
"ModifiedDate": modifiedDate!.toIso8601String(),

"Sizes": List<dynamic>.from(sizes!.map((x) => x.toJson())),

return reverseMap!;

最后一个是最不可能出现问题的，因为您在reverseMap的几行中分配了reverseMap 。

这意味着images 、 featureBoxImages 、 modifiedDate或sizes为空。 这是我对哪个的最佳猜测，但错误应该给你一行，你在其中进行了空检查，如果你告诉我那行说的是什么会很有帮助。

images分配如下： Images.fromJson(json["Images"]), ，但你的 json 从不分配'Images' ，我猜你的意思是'Image' 。

类似的事情发生在featureBoxImages ，你使用'FeatureBoxImages'分配它，但在你的 JSON 上你使用'FeatureBoxImage' 。

modifiedDate对我来说看起来不错，我不认为它是 null，但也许DateTime.parse有机会返回 null？

sizes对我来说也很好看，我不认为这是问题所在。

希望我提到的其中一项更改可以解决您的问题！

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