我有以下问题。 我向 FatSecret API 发送请求以获取食物的详细信息。 如果我解码一种普通食品，它会起作用，但如果我得到一种品牌食品，它就不起作用。
我的结构看起来像:
struct fatsecretFood : Decodable {
let food : Food
struct Food : Decodable {
let brand_name: String?
let food_id: String?
let food_name: String?
let food_type: String?
let food_url: String?
let servings : Servings
struct Servings : Decodable {
let serving : [Serving]
struct Serving : Decodable {
let serving_id: String?
let serving_description: String?
let serving_url: String?
let metric_serving_amount: String?
let metric_serving_unit: String?
let number_of_units: String?
let measurement_description: String?
let calories: String?
let carbohydrate: String?
let protein: String?
let fat: String?
let saturated_fat: String?
let polyunsaturated_fat: String?
let monounsaturated_fat: String?
let trans_fat: String?
let cholesterol: String?
let sodium: String?
let potassium: String?
let fiber: String?
let sugar: String?
let vitamin_a: String?
let vitamin_c: String?
let calcium: String?
let iron: String?
}
}
}
}
出现错误的代码行:
let data = Data(requestResponse.utf8)
var foodDetails: fatsecretFood!
var errors: fatsecretError!
do {
let result = try JSONDecoder().decode(fatsecretFood.self, from: data)
foodDetails = result
} catch { print(error) }
return foodDetails!
在返回时我得到错误:
typeMismatch(Swift.Array<Any>, Swift.DecodingError.Context(codingPath: [CodingKeys(stringValue: "food", intValue: nil), CodingKeys(stringValue: "servings", intValue: nil), CodingKeys(stringValue: "serving", intValue: nil)], debugDescription: "Expected to decode Array<Any> but found a dictionary instead.", underlyingError: nil))
示例通用食品(有效)的 JSON 如下所示:
{
"food": {
"food_id": "38884",
"food_name": "Chocolate Chip Cookies (Soft Type)",
"food_type": "Generic",
"food_url": "https://www.fatsecret.com/calories-nutrition/usda/chocolate-chip-cookies-(soft-type)",
"servings": {
"serving": [
{
"calcium": "0",
"calories": "130",
"carbohydrate": "16.75",
"cholesterol": "0",
"fat": "6.89",
"fiber": "0.9",
"iron": "4",
"measurement_description": "oz",
"metric_serving_amount": "28.350",
"metric_serving_unit": "g",
"monounsaturated_fat": "3.695",
"number_of_units": "1.000",
"polyunsaturated_fat": "0.992",
"potassium": "26",
"protein": "0.99",
"saturated_fat": "2.101",
"serving_description": "1 oz",
"serving_id": "38785",
"serving_url": "https://www.fatsecret.com/calories-nutrition/usda/chocolate-chip-cookies-(soft-type)?portionid=38785&portionamount=1.000",
"sodium": "92",
"vitamin_a": "0",
"vitamin_c": "0"
},
{
"calcium": "0",
"calories": "69",
"carbohydrate": "8.86",
"cholesterol": "0",
"fat": "3.64",
"fiber": "0.5",
"iron": "2",
"measurement_description": "cookie",
"metric_serving_amount": "15.000",
"metric_serving_unit": "g",
"monounsaturated_fat": "1.955",
"number_of_units": "1.000",
"polyunsaturated_fat": "0.525",
"potassium": "14",
"protein": "0.52",
"saturated_fat": "1.112",
"serving_description": "1 cookie",
"serving_id": "38786",
"serving_url": "https://www.fatsecret.com/calories-nutrition/usda/chocolate-chip-cookies-(soft-type)?portionid=38786&portionamount=1.000",
"sodium": "49",
"vitamin_a": "0",
"vitamin_c": "0"
},
{
"calcium": "2",
"calories": "458",
"carbohydrate": "59.10",
"cholesterol": "0",
"fat": "24.30",
"fiber": "3.2",
"iron": "13",
"measurement_description": "g",
"metric_serving_amount": "100.000",
"metric_serving_unit": "g",
"monounsaturated_fat": "13.034",
"number_of_units": "100.000",
"polyunsaturated_fat": "3.500",
"potassium": "93",
"protein": "3.50",
"saturated_fat": "7.411",
"serving_description": "100 g",
"serving_id": "61615",
"serving_url": "https://www.fatsecret.com/calories-nutrition/usda/chocolate-chip-cookies-(soft-type)?portionid=61615&portionamount=100.000",
"sodium": "326",
"vitamin_a": "0",
"vitamin_c": "0"
}
]
}
}
}
示例品牌食品的 JSON(不起作用)如下所示:
{
"food": {
"brand_name": "Pepperidge Farm",
"food_id": "61348",
"food_name": "Soft Baked Sugar Cookies",
"food_type": "Brand",
"food_url": "https://www.fatsecret.com/calories-nutrition/pepperidge-farm/soft-baked-sugar-cookies",
"servings": {
"serving": {
"calcium": "0",
"calories": "140",
"carbohydrate": "22",
"cholesterol": "10",
"fat": "5",
"fiber": "0",
"iron": "4",
"measurement_description": "serving",
"metric_serving_amount": "31.000",
"metric_serving_unit": "g",
"monounsaturated_fat": "1.5",
"number_of_units": "1.000",
"polyunsaturated_fat": "0.5",
"protein": "2",
"saturated_fat": "2.5",
"serving_description": "1 cookie",
"serving_id": "103910",
"serving_url": "https://www.fatsecret.com/calories-nutrition/pepperidge-farm/soft-baked-sugar-cookies",
"sodium": "90",
"sugar": "11",
"trans_fat": "0",
"vitamin_a": "0",
"vitamin_c": "0"
}
}
}
}
我没有找到错误。有人可以帮我吗？ 谢谢
最佳答案
请学会理解错误信息，它很容易阅读
typeMismatch(Swift.Array, Swift.DecodingError.Context(codingPath: [CodingKeys(stringValue: "food", intValue: nil), CodingKeys(stringValue: "servings", intValue: nil), CodingKeys(stringValue: "serving", intValue: nil)], debugDescription: "Expected to decode Array but found a dictionary instead.", underlyingError: nil))
-
typeMismatch表示您声明了错误的类型 (Swift.Array<Any>)。 codingPath数组表示受影响位置的关键路径food/servings/serving.debugDescription的预期 部分描述你的错误(数组) found 部分描述了实际类型(字典，它是Codable方面的结构)。
为了能够解码数组和字典类型，您必须添加自定义初始化程序。 serving 的最终类型始终是一个数组。
struct Servings : Decodable {
let serving : [Serving]
private enum CodingKeys : String, CodingKey { case serving }
init(from decoder : Decoder) throws {
let container = try decoder.container(keyedBy: CodingKeys.self)
do {
let servingDictionary = try container.decode(Serving.self, forKey: .serving)
serving = [servingDictionary]
} catch DecodingError.typeMismatch {
serving = try container.decode([Serving].self, forKey: .serving)
}
}
}
注意事项:
- 名称结构始终以大写字母开头。
- 不要使用snake_cased 变量名。添加
.convertFromSnakeCase策略并声明 camelCased 名称。 - 不要粗心地将所有内容都声明为可选的。似乎至少
Serving对象总是发送所有键。
关于json - Swift JSOn 解码错误 : Expected to decode Array<Any> but found a dictionary instead，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/57818665/