Fetching Single Event From a Firebase Realtime Database Child-CodePudding

I'm having trouble fetching data from a child node in a Firebase Realtime Database reference. I'm uploading a job request detail node to my logged in customer reference, however when I try to fetch the node, my controller won't read it and display it on the screen. Is it because I have to set my fetch API function to fetch the most recent job request detail node that was recently added by doing .childAdded instead if .value? Or am I doing something wrong when I call the fetch function in my controller itself? The reason why I ask is because I try to print jobRequest in my fetchCustomerJobRequest() and it doesn't print. Also, the reason why I have a question mark at the end of my var jobReuest: JobRequest? is because I initiate it in my FindEmployeeJobRequestController for the first time through the app, if that's correct too? Thank you in advance!

Database Reference Setup

JobRequest Model

struct JobRequest {
    
    let uid: String
    let fullname: String
    let username: String
    let address: String
    let firstDateAndTimes: String
    let secondDateAndTimes: String
    let thirdDateAndTimes: String
    let timeConstraints: String
    let jobDescription: String
    
    init(dictionary: [String : Any]) {
        self.uid = dictionary["uid"] as? String ?? ""
        self.fullname = dictionary["fullname"] as? String ?? ""
        self.username = dictionary["username"] as? String ?? ""
        self.address = dictionary["address"] as? String ?? ""
        self.firstDateAndTimes = dictionary["firstDateAndTimes"] as? String ?? ""
        self.secondDateAndTimes = dictionary["secondDateAndTimes"] as? String ?? ""
        self.thirdDateAndTimes = dictionary["thirdDateAndTimes"] as? String ?? ""
        self.timeConstraints = dictionary["timeConstraints"] as? String ?? ""
        self.jobDescription = dictionary["jobDescription"] as? String ?? ""
    }
    
}

Services API

struct CustomerService {

static func fetchCustomerJobRequest(completion: @escaping(JobRequest) -> Void) {
        
        guard let uid = Auth.auth().currentUser?.uid else { return }
        
        REF_CUSTOMERS.child(uid).child("job-request-details").childByAutoId().observeSingleEvent(of: .value) { snapshot in
            guard let dictionary = snapshot.value as? [String : Any] else { return }
            let jobRequest = JobRequest(dictionary: dictionary)
            completion(jobRequest)
        }
        
}

}

FindEmployeeJobRequestController

// MARK: - Properties

var jobRequest: JobRequest? {
   didSet {
      configure()
   }
}

// MARK: - Lifecycle

override func viewDidLoad() {
   super.viewDidLoad()
        
   fetchCustomerJobRequest()
}

// MARK: - API

func fetchCustomerJobRequest() {
    CustomerService.fetchCustomerJobRequest { jobRequest in
        self.jobRequest = jobRequest
    }
}

// MARK: - Helper Functions

fileprivate func configure() {
        
    guard let jobRequest = jobRequest else { return }
    let viewModel = JobRequestViewModel(jobRequest: jobRequest)
        
    fullnameDetailsLabel.text = viewModel.fullname
    usernameDetailsLabel.text = "@"   viewModel.username
    addressDetailsLabel.text = viewModel.address
    firstDateAndTimeDetailsLabel.text = viewModel.firstDateAndTimes
    secondDateAndTimeDetailsLabel.text = viewModel.secondDateAndTimes
    thirdDateAndTimeDetailsLabel.text = viewModel.thirdDateAndTimes
    timeConstraintsDetailsLabel.text = viewModel.timeConstraints
    jobDescriptionDetailsLabel.text = viewModel.jobDescription
        
}

CodePudding user response：

This code doesn't do what you expect it to do:

REF_CUSTOMERS.child(uid).child("job-request-details").childByAutoId().observeSingleEvent(of: .value)

Calling childByAutoId() it generates a new unique location, that you then call observeSingleEvent on. But since you don't write anything to this location, there will never be any value for the listener to get.

So the snapshot.value will be nil in the callback, and in fact snapshot.exists() will be false.