使用Codable swift解析时忽略数组中的null对象

Question

我正在用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"
    }
]

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User型号：

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)

现在我的问题是在null数组中的searchResult。它解析正确，当我访问data中的paginationModel时，我发现null在数组中。

在解析API时如何忽略所有null，结果将是一个没有任何null的数组

Answer 1

首先，我建议总是认为PaginationModel是由数组组成的。您不必将[User]作为泛型类型传递，您只需传递User即可。然后解析器可以使用它解析数组并自动处理null的知识：

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 }
    }
}

您可能希望在此处删除选项并使用一些默认值：

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 }
    }
}

Answer 2

简单的解决方案，解码后过滤data

let responseObject = try JSONDecoder().decode(PaginationModel<[User?]>.self, from: data)
responseObject.data = responseObject.data?.filter{$0 != nil}

Answer 3

您可以在解码中添加数组类型检查：

  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)

    //add the following:
    if let array =  self.data as? Array<Any?> {
        self.data = ( array.compactMap{$0} as? T)
    }
}