json - 使用 Codable swift 解析时忽略数组中的空对象

Question

我正在使用 swift Codable 解析这个 API

"total": 7,
"searchResult": [
    null,
    {
        "name": "joe"
        "family": "adam"
    },
    null,
    {
        "name": "martin"
        "family": "lavrix"
    },
    {
        "name": "sarah"
        "family": "mia"
    },
    null,
    {
        "name": "ali"
        "family": "abraham"
    }
]

使用这个 PaginationModel:

class PaginationModel<T: Codable>: Codable {
    var total: Int?
    var data: T?

    enum CodingKeys: String, CodingKey {
        case total
        case data = "searchResult"
    }

    required init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        self.total = try container.decodeIfPresent(Int.self, forKey: .total)
        self.data = try container.decodeIfPresent(T.self, forKey: .data)
    }
}

和用户模型:

struct User: Codable {
    var name: String?
    var family: String?
}

我这样调用 jsonDecoder 来解析 API json:

let responseObject = try JSONDecoder().decode(PaginationModel<[User?]>.self, from: json)

现在我的问题是 searchResult 数组中的 null。它解析正确，当我访问 paginationModel 中的 data 时，我在数组中找到了 null。

如何在解析API时忽略所有null，结果将是一个没有任何null的数组

Answer 1

首先，我建议始终考虑 PaginationModel 由数组组成。您不必将 [User] 作为通用类型传递，您可以只传递 User。然后解析器可以使用它解析数组的知识并自动处理 null:

class PaginationModel<T: Codable>: Codable {
    var total: Int?
    var data: [T]?

    enum CodingKeys: String, CodingKey {
        case total
        case data = "searchResult"
    }

    required init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        self.total = try container.decodeIfPresent(Int.self, forKey: .total)

        self.data = (try container.decodeIfPresent([T?].self, forKey: .data))?.compactMap { $0 }
    }
}

您可能想在此处删除可选值并改用一些默认值:

class PaginationModel<T: Codable>: Codable {
    var total: Int = 0
    var data: [T] = []

    enum CodingKeys: String, CodingKey {
        case total
        case data = "searchResult"
    }

    required init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        self.total = (try container.decodeIfPresent(Int.self, forKey: .total)) ?? 0

        self.data = ((try container.decodeIfPresent([T?].self, forKey: .data)) ?? []).compactMap { $0 }
    }
}