Retrieve array of dictionary from Firebase & Swift 3

Question

I have a json database on firebase and trying to get them and put into local array of dictionaries.

My json model on Firebase

My struct model is also like below

struct Places {
var type:String!
var country:String!
var name:String!
var image:String!
var coords:[Coords]!


init(type: String, country: String, name: String, image: String, coords: [Coords]) {
    self.type = type
    self.country = country
    self.name = name
    self.image = image
    self.coords = coords
}

init(snapshot: FIRDataSnapshot) {

    let snapshotValue = snapshot.value as! [String:Any]

    type = snapshotValue["type"] as! String
    country = snapshotValue["country"] as! String
    name = snapshotValue["name"] as! String
    image = snapshotValue["image"] as! String
    coords = snapshotValue["coords"] as! [Coords]!
}

}

And also [Coords] struct model like below:

struct Coords {

var latStart:String!
var latEnd:String!
var lonStart:String!
var lonEnd:String!

init(latStart: String, latEnd: String, lonStart: String, lonEnd: String) {
    self.latStart = latStart
    self.latEnd = latEnd
    self.lonStart = lonStart
    self.lonEnd = lonEnd
}

}

And I am trying to get and put json data by below code:

placesRef.observeSingleEvent(of: .value, with: { (snapshot) in

            if !snapshot.exists() {
                print("data not exist")
                return
            }

                var plc: [Places] = []

                for eachPlace in (snapshot.children){
                    let place = Places(snapshot: eachPlace as! FIRDataSnapshot)

                    plc.append(place)
                }

            self.allPlaces = plc

The problem is that I can get the array of dictionary except coords dictionary inside array of dictionary. [Coords] dictionary seems null and I would like to know what the problem is. Thanks for any suggestion.

Answer 1

Because snapshotValue["coords"] as! [Coords]! snapshotValue["coords"] as! [Coords]! are not Coords yet. They are just dictionaries. You have to go through each dictionary in snapshotValue[“coords”] and init a Coords object, then when you're finished group them all into an array and assign it to self.coords of the Places struct. The map function is really convenient for this.

Example:

I would change the Coords init function to something like:

init(dictionary: [String : AnyObject]) {
    self.latStart = dictionary["lat1"] as? String
    //...
    //...
}

Then in Places init use something like:

coords = (snapshotValue["coords"] as? [[String : AnyObject]])?.map({ Coord(dictionary: $0) })

I didn't test this and making some assumptions here, but you should be able to make something similar work.