ignore null object in array when parse with Codable swift

Question

i'm parsing this API with swift Codable

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

with this 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)
    }
}

and User Model:

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

i call jsonDecoder like this to parse API json:

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

now my problem is null in searchResult Array. it parsed correctly and when i access to data in paginationModel i found null in array.

how can i ignore all null when parsing API, and result will be an array without any null

Answer 1

In the first place, I would advise to always consider PaginationModel to be composed from arrays. You don't have to pass [User] as the generic type, you can just pass User. Then the parser can use the knowledge that it parses arrays and handle null automatically:

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 }
    }
}

You might want to remove optionals here and use some default values instead:

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 }
    }
}