Flutter开发：ListView加载数据时int与double类型不匹配错误求助

问题根源是接口返回的kcal、fats、carbs、protein字段为整数类型（int），但你的FoodModel中这些字段定义为double?，直接赋值会触发类型不兼容错误。之前接口返回字符串时，Flutter会隐式处理类型转换，现在返回原始数值类型就暴露了这个问题。

修复方案 #

修改FoodModel的fromJson构造函数，对数值字段进行显式类型转换，确保int类型能转为double类型，同时兼容null的情况：

class FoodModel {
  int? foodId;
  String? foodNameEn;
  String? foodNameAr;
  double? kcal;
  double? fats;
  double? carbs;
  double? protein;
  String? createTime;
  int? foodTypeId;
  String? foodImage;

  FoodModel(
      {this.foodId,
      this.foodNameEn,
      this.foodNameAr,
      this.kcal,
      this.fats,
      this.carbs,
      this.protein,
      this.createTime,
      this.foodTypeId,
      this.foodImage});

  FoodModel.fromJson(Map<String, dynamic> json) {
    foodId = json['food_id'];
    foodNameEn = json['food_name_en'];
    foodNameAr = json['food_name_ar'];
    // 显式转换数值类型，兼容int和double，同时处理null
    kcal = json['kcal']?.toDouble();
    fats = json['fats']?.toDouble();
    carbs = json['carbs']?.toDouble();
    protein = json['protein']?.toDouble();
    createTime = json['create_time'];
    foodTypeId = json['food_type_id'];
    foodImage = json['food_image'];
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = <String, dynamic>{};
    data['food_id'] = foodId;
    data['food_name_en'] = foodNameEn;
    data['food_name_ar'] = foodNameAr;
    data['kcal'] = kcal;
    data['fats'] = fats;
    data['carbs'] = carbs;
    data['protein'] = protein;
    data['create_time'] = createTime;
    data['food_type_id'] = foodTypeId;
    data['food_image'] = foodImage;
    return data;
  }
}

说明 #

• 使用?.toDouble()操作符：先判断字段是否为null，不为null则调用toDouble()将int转为double，避免空指针异常。
• 这种写法同时兼容接口返回int、double或null的情况，彻底解决类型不匹配问题。

内容的提问来源于stack exchange，提问作者Toxicless