CODEWITHSUNDEEP
iosswiftuitableviewcore-datarelationship
fizzy
fizzy

Reputation: 33

Core Data One-To-Many Swift

The question i have is in regards to a Core Data one-to-many relationship as of right now i have my app being able to let the user input employee information and saving to core data, then updating the employee table view. The problem i face is the relationship between the employee and delivery. Im currently trying to display a specific employees deliveries when clicking on an employee in the employee table view. After selecting an employee from the employee tableView i want it to segue to another tableview and display the employees deliveries in another UITableview.

What I'm trying to Accomplish:

1) Display Specific Employee's Deliveries

2) Add deliveries to the NSSet

Here are my two managedObjects

extension Delievery {

    @NSManaged var address: String?
    @NSManaged var phoneNumber: String?
    @NSManaged var subTotal: NSNumber?
    @NSManaged var total: NSNumber?
    @NSManaged var employee: Employee?

}

extension Employee {

    @NSManaged var first: String?
    @NSManaged var last: String?
    @NSManaged var phoneNumber: String?
    @NSManaged var wage: NSNumber?
    @NSManaged var id: NSNumber?
    @NSManaged var delievery: NSSet?

}

how i prepared for segue from employeeTableViewController to deliveryTableViewContorller

override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
    if segue == "DelieverySegue"{
        let employeeDeliveries = segue.destinationViewController as! DelieveryTableViewController



        let indexPath = self.tableView.indexPathForSelectedRow



        let selectedEmployee = employees[indexPath!.row]

        employeeDeliveries.employee = selectedEmployee





    }
}

The variables of the deliveryTableViewController are

var employee: NSManagedObject!


var deliveries : [NSManagedObject]!


var managedObjectContext : NSManagedObjectContext!

In this photo it shows the rest of my deliveryTableViewController the problem i have is how do i return the amount of deliveries for a specific employee in the numberOfRowsInSection function and how do i fetch the deliveries of the employee. deliveryTableViewController set up

In this last photo my question is how to i add this delivery entry to the employee selected? this is how I'm currently saving my delivery entries how i save my delivery entries

If you made it this far i appreciate you looking through my problem. If anyone can help me the slightest with this issue i'd appreciate it if you feel i've left some information out that is needed please let me know.

UPDATE:

Here is the picture of the DelieveryTableViewController (yes i know i spelt delivery wrong)

Picture of DelieveryTableViewController with viewDidLoad()

also need to set the NSPredicate

Picture of DeliveryTableViewController fetchRequest function

this is home I'm preparing for segue in EmployeeTableViewController

enter image description here

these are my variables for EmployeeTableViewController

enter image description here

Upvotes: 1

Views: 425

Answers (1)

pbasdf
pbasdf

Reputation: 21536

Setting the relationship

With one to many relationships, it is easiest to set the to-one relationship:

delivery.employee = employee

Put this line in your completeOrder method (you may need to pass the employee reference from a previous VC). CoreData will automatically set the inverse relationship for you, adding delivery to the deliveries set for the employee.

Showing the Deliveries in a Table View

Having set the relationship, the deliveries property of employee contains a set of Delivery objects to which it is related. To display these in a table view, create your deliveries array from this set (eg. in viewDidLoad):

deliveries = employee.delivery.allObjects()

Your numberOfRowsInSection can then just use deliveries.count and the cellForRowAtIndexPath can use deliveries[indexPath.row] to determine which Delivery to display in each cell.

(An alternative is to fetch the deliveries array in the normal way, but to use a predicate to restrict the results to those that are related to your employee:

fetch.predicate = NSPredicate(format:"employee == %@", employee)

Longer term, you should consider using NSFetchedResultsController which is designed for displaying CoreData objects in table view.)

Update

You don't need the thisEmployee variable. Just change the Employee variable to be Employee class:

var employee : Employee!

Then you should be able to set

deliveries = employee.deliveries?.allObjects as! [NSManagedObject]

And in your fetchDelivery() method, set the predicate with

fetchRequest.predicate = NSPredicate(format:"employee == %@", employee)

(after let fetchRequest = ....).

Update 2

It's difficult to see where the nil value is. To track it down, try printing the value of employee in the viewDidLoad method of the DelieveryTableViewController. If it's nil, there is a problem with passing the value in prepareForSegue. If not, print employee.deliveries, etc. Post your results.

Upvotes: 1

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