Swift JSONDecoder handling Dictionary of Array of Dictionary

Question

This is a model design related question related to JSONDecoder codeable functionality on swift.

I have the following JSON:

"author": {
    "name": "abc",
    "emailAddress": "[email protected]",
    "id": 8665,
    "displayName": "A B C",
    "active": true,
    "slug": "abc",
    "type": "NORMAL",
    "links": {
        "self": [
                  {
                    "href": "some_href"
                  }
                ]
    }
 }

I am trying to decode this using the new swift 4 Codeable functionality.

Hence I created my struct as follows:

struct Author: Codeable {
    let name: String,
    let emailAddress: String,
    let id: String,
    let displayName: String,
    let active: String,
    let type: String,
    let links: [String: [Link]] 
}

struct Link: Codeable {
    let href: String
}

Once i run a JSONDecoder().decode on this json i get the model objects in the above format. However, the links property in Author class is obtained as a dictionary. And now to access the value of self field i need to roughly do as follows:

let selfLink = author.links["self"]
let href = selfLink[0].href

Is there a better way to model the struct so that this can be avoided?

Thank you @code-different will try this out.

Vibin B. Nair
– Vibin B. Nair

2018-05-14 10:50:59 +00:00
Commented May 14, 2018 at 10:50 — Vibin B. Nair
– Vibin B. Nair, Commented May 14, 2018 at 10:50
Thank you @jogendar-choudhary. Will try out this approach.

Vibin B. Nair
– Vibin B. Nair

2018-05-14 10:51:32 +00:00
Commented May 14, 2018 at 10:51 — Vibin B. Nair
– Vibin B. Nair, Commented May 14, 2018 at 10:51

Jogendar Choudhary · Accepted Answer · 2018-05-13 19:36:14Z

1

Yes, You can do this by adding one more variable like that:

struct Author: Codable {
    let name: String
    let emailAddress: String
    let id: String
    let displayName: String
    let active: String
    let type: String
    let links: [String: [Link]]
    var linkArr: [Link]? {
        return links["self"]
    }
}

And get directly like that:

author.linkArr[0].href

answered May 13, 2018 at 19:36

Jogendar Choudhary

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Code Different · Accepted Answer · 2018-05-14 00:05:26Z

1

If you are sure that each author always has at least 1 href, you can add a computed property:

struct Author: Codable {
    let name: String
    let emailAddress: String
    let id: String
    let displayName: String
    let active: String
    let type: String

    let links: [String: [Link]]     
    var href: String {
        return links["self"]!.first!.href
    }
}

You can also make links inaccessible from outside by declaring it private.

answered May 14, 2018 at 0:05

Code Different

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Comments

Au Ris · Accepted Answer · 2018-05-14 09:20:08Z

One thing that is not very usual or at least named inappropriately in your JSON is that links property is actually not a collection but a wrapper object for a collection self. That's why I would stay true to what the data is and map the links property to name linksWrapper (an object) and self to links (a collection).

struct Author: Codable {
    let name: String
    let emailAddress: String
    let id: Int
    let displayName: String
    let active: Bool
    let slug: String
    let type: String
    let linksWrapper: LinksWrapper

    enum CodingKeys: String, CodingKey {
        case name, emailAddress, id, displayName, active, slug, type
        case linksWrapper = "links"
    }
}

struct LinksWrapper: Codable {
    let links: [Link]

    enum CodingKeys: String, CodingKey {
        case links = "self"
    }
}

struct Link: Codable {
    let href: String
}

Then you can access the links in the same hierarchical order like your JSON model suggests, but with more meaningful names:

let myLinks = author.linksWrapper.links.first

But for your convenience you can add a readonly links property to Author:

var links: [Link] {
    return linksWrapper.links
}

Then you can access links directly:

let myLinks = author.links

However if you have a chance to fix this in the JSON structure itself then do that instead.

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