decoding an array of objects in swift

Question

I have an array of objects

{"total_rows":5,"offset":0,"rows":[
{"id":"index","key":"index","value":{"rev":"4-8655b9538706fc55e1c52c913908f338"}},
{"id":"newpage","key":"newpage","value":{"rev":"1-7a27fd343ff98672236996b3fe3abe4f"}},
{"id":"privacy","key":"privacy","value":{"rev":"2-534b0021f8ba81d09ad01fc32938ce15"}},
{"id":"secondpage","key":"secondpage","value":{"rev":"2-65847da61d220f8fc128a1a2f1e21e89"}},
{"id":"third page","key":"third page","value":{"rev":"1-d3be434b0d3157d7023fca072e596fd3"}}
]}

that I need too fit in struct and then decode in swift. My current code is:

struct Index: Content {

    var total_rows: Int
    var offset: Int
   // var rows: [String: String] // I don't really know what I am doing here 

}

and the router (using vapor)

router.get("/all") { req -> Future<View> in
        let docId = "_all_docs"
        print(docId)
        let couchResponse = couchDBClient.get(dbName: "pages", uri: docId, worker: req)
        guard couchResponse != nil else {
            throw Abort(.notFound)
        }

        print("one")
        return couchResponse!.flatMap { (response) -> EventLoopFuture<View> in
            guard let data = response.body.data else { throw Abort(.notFound) }

            print(data)

            let decoder = JSONDecoder()
            let doc = try decoder.decode(Index.self, from: data)

            let allDocs = Index(
                total_rows: doc.total_rows,
                offset: doc.offset
                //rows: doc.rows
            )
            print("test after allDocs")
            return try req.view().render("index", allDocs)
        }
    }

to summarise all is fine for the first level (total rows and offset are int and properly decoded) but how can I include in my structure the rows: array and assign thee parsed values to it ?

If your Index conforms to Codable (or Decodable), which I guess it does, based on your expectation to be decoded by JSONDecoder, then your rows would be an array of Row structs that are also decodable, for which their value would be another decodable etc. I hope that this makes sense... — Alladinian
– Alladinian, Commented Nov 30, 2019 at 23:40
@Alladinian could you share an example in the answer? very new to swift so I appreciate your help — devnull
– devnull, Commented Nov 30, 2019 at 23:44

Rob Napier · Accepted Answer · 2019-11-30 23:45:18Z

2

You're on the right road, you just need to keep going.

struct Index: Decodable {
    var total_rows: Int
    var offset: Int
    var rows: [Row]
}

Then you define a Row:

struct Row: Decodable {
    var id: String
    var key: String
    var value: Value
}

It's not really clear what a Value is in this context, but just to keep the structure.

struct Value: Decodable {
    var rev: String
}

And that's all.

let index = try JSONDecoder().decode(Index.self, from: jsonData)

answered Nov 30, 2019 at 23:45

Rob Napier

301k37 gold badges492 silver badges660 bronze badges

Sign up to request clarification or add additional context in comments.

6 Comments

devnull Over a year ago

awesome! one question thou: how would. populate these 3 structures? at the moment I have let allDocs = Index( total_rows: doc.total_rows, offset: doc.offset, rows: doc.rows // this s obviously wrong as it is ) thanks

devnull Over a year ago

tried let doc = try decoder.decode(Index.self, from: data) let allDocs = Index( total_rows: doc.total_rows, offset: doc.offset, rows: doc.rows ) print("test after allDocs") return try req.view().render("index", allDocs) }. but I get Argument type 'Index' does not conform to expected type 'Encodable'

Joakim Danielson Over a year ago

@devnull in the answer above index is of type Index already so there is no need to create another object allDocs, use index directly instead.

devnull Over a year ago

@JoakimDanielson thanks I did that so now I have let index = try JSONDecoder().decode(Index.self, from: data) return try req.view().render("index", index) but still get Argument type 'Index' does not conform to expected type 'Encodable'

Joakim Danielson Over a year ago

@devnull Change Index and Row to conform to Codable instead

|

Collectives™ on Stack Overflow

decoding an array of objects in swift

1 Answer 1

6 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

6 Comments

Your Answer

Sign up or log in

Post as a guest

Related