Swift - decode only interested elements

Question

I have a huge json data obtained from HTTP response and I need only a particular portion to be decoded as a model.

{
    "root1": {
        "items": [
            {
                ...
            },
            {
                ...
            },
            {
                ...
            },
            {
                ...
            },
            {
                ...
            }
        ]
    },
    "root2": {
        ...
    },
    "page": {
        "size": 10,
        "totalElements": 5,
        "totalPages": 1,
        "number": 0
    }
}

This is my json template and I do not want to create model for root elements. I am interested only in the items array. Any direct way to decode it?

Answer 1

You can select what to decode by using a CodingKey enum but you still need to decode from the top/root level.

struct Response: Decodable {
    let root1: Root1

    enum CodingKeys: String, CodingKey {
        case root1
    }
}

struct Root1: Decodable {
    let items: [Item]

    enum CodingKeys: String, CodingKey {
        case items
    }
}

and then the decoding could be done as

var items: [Item] = []
do {
     items = try JSONDecoder().decode(Response.self, from: data).root1.items
} catch {

}