Firebase create model which has optional values in swift

Question

I would like to create model which has optional values.
I implemented

flatmap

to achieve that. node look like this and imageUrl does not exist everytime like so.

"Post": {

    "uid": {

　　　"autoid"{

       "Text": "some text",

       "Date": "some date",

       "imageUrl": {

         autoID1: url1,

         autoID2: url2

      }

     },

    "autoid"{

      "Text": "some text",

      "Date": "some date"

     } 

    }

  }

I created a model here

import UIKit

import Firebase



extension  DataSnapshot {

    var snapshots: [DataSnapshot] {

        return children.allObjects.flatMap({ $0 as? DataSnapshot })

    }

    var string: String? { return value as? String }

    var url: URL? { return string.flatMap({ URL(string: $0) }) }

    var urls: [URL] { return snapshots.flatMap({ $0.url }) }

}



struct Post {



    let snapshot: DataSnapshot?



    var Date: String!

    var imageUrl: [URL]?

    var Text: String!



    init(snapshot: DataSnapshot) {



        self.snapshot = snapshot

        self.Date = snapshot.child["Date"].string

        self.imageUrl = snapshot.child["imageUrl"].urls

        self.Text = snapshot.child["Text"].string

    }

}

but inside

init

, error says

Value of type 'DataSnapshot' has no member 'child'

Does anyone know how to solve this?
Also is this right way to create function like twitter post with multiple images and sometimes images are none, only text displayed.

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Answer 1

DataSnapshot doesn't have the member child, doc here. So to be able to extract something from the DataSnapshot, you might use this idea:

if let value = snapshot.value as? [String: Any] {
  self.Date = value["Date"] as? String ?? ""
  self.Text = value.child["Text"] as? String ?? ""

  // extracting the urls
  if let urls = value.child["tweetImageUrl"] as? [String:String] {
    self.imageUrl = urls.flatMap { k,v in URL(string:v) }
  }
}

Note that: flatMap is awesome because provide the possibility to skip automatically all the iterations that are returning an optional value.

Firebase create model which has optional values in swift

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