In a tableView I have a list of jobs. These jobs can be accessed by multiple users, therefore I need to use FIRTransaction. Based on the result of the first write to FirebaseDatabase, I need to write/not write to another path in Firebase. The schema is as follows:
//Claim job by - Cleaner
//cleaner tries to claim booking at Users/UID/cus/bookingNumber
//if FIRMutableData contains a key ‘claimed’ or key:value “claimed”:true
//update at Users/UID/cus/bookingNumber with key:value
//based on response received write or not to another path
//write to Cleaners/UID/bookingNumber
//key:value
If the internet connection drops before client app receives response from firebase server, write to Cleaners/UID/bookingNumber will not be made.
How can I solve this problem?
@IBAction func claimJob(_ sender: Any) {
dbRef.runTransactionBlock({ (_ currentData:FIRMutableData) -> FIRTransactionResult in
//if valueRetrieved is nil abort
guard let val = currentData.value as? [String : AnyObject] else {
return FIRTransactionResult.abort()
}
self.valueRetrieved = val
guard let uid = FIRAuth.auth()?.currentUser?.uid else {
print("abort no uid line 80")
return FIRTransactionResult.abort()
}
self.uid = uid
for key in self.valueRetrieved.keys {
//unwrap value of 'claimed' key
guard let keyValue = self.valueRetrieved["Claimed"] as? String else {
print("abort line 88")
return FIRTransactionResult.abort()
}
//check if key value is true
if keyValue == "true"{
//booking already assigned show alert,stop transaction
self.alertText = "Booking already taken, please refresh table!"
self.alertActionTitle = "OK"
self.segueIdentifier = "unwindfromClaimDetailToClaim"
self.showAlert()
return FIRTransactionResult.abort()
} else {
//write the new values to firebase
let newData = self.createDictionary()
currentData.value = newData
return FIRTransactionResult.success(withValue: currentData)
}//end of else
}//end of for key in self
return FIRTransactionResult.abort()
}) {(error, committed,snapshot) in
if let error = error {
//display an alert with the error, ask user to try again
self.alertText = "Booking could not be claimed, please try again."
self.alertActionTitle = "OK"
self.segueIdentifier = "unwindfromClaimDetailToClaim"
self.showAlert()
//what if internet connection drops here or client quits app ????????????
} else if committed == true {
//write to Cleaners/UID/bookingNumber
//what if internet connection drops here or client quits app??????
self.cleanersRef.setValue(snapshot?.value)
self.alertText = "Booking claimed.Please check your calendar"
self.alertActionTitle = "OK"
self.segueIdentifier = "unwindfromClaimDetailToClaim"
self.showAlert()
}
}
}//end of claimJob button
