Fetch attributes from multiple entities in CoreData Swift

Question

I have two Core data entities named Patients and Recordings. A patient can have a single or multiple recordings. I want when a view load i can fetch information of both the entities attributes in a single fetch like we did in sql using join. Any help?

Core Data Model Image Search Patient

A patient can have a single recording dictation or multiple. Now on view load i show all the patients from core data patients entity. I want to show images in table cell that if patient has recording done it shows recording icon or if has transcription done it has transcription icon as well and none of the icon shows if patient has no recording.i want to get datails of both the table in a single fetch.

func FetchSearchData() {

        let uid = defaults.value(forKey: "UserID")
        searchTasks.removeAll()

        let fetchRequest:NSFetchRequest<Patients> = Patients.fetchRequest()
        let sortDescriptor = NSSortDescriptor(key: "dateSchedule", ascending: true)
        fetchRequest.sortDescriptors = [sortDescriptor]
        let predicate = NSPredicate(format: "(userID=%@)", uid as! CVarArg)
        fetchRequest.predicate = predicate

        do {
            let count = try getContext().count(for: fetchRequest as! NSFetchRequest<NSFetchRequestResult>)

            if count > 0 {

                let fetchResult = try getContext().fetch(fetchRequest)

                for item in fetchResult {
                    searchTasks.append(item)
                    searchTableView.reloadData()
                }
            } else {
                searchTableView.reloadData()
            }

        }catch {
            print(error.localizedDescription)
        }

    }

I have create relationship like we see in image. How can I check now which patient have recording exists?

I'm not a Core Data expert but what have you tried so far? What failed? What does your Core Data model look like? What fetch request are you trying? — Robotic Cat
– Robotic Cat, Commented Apr 6, 2017 at 15:20

Tom Harrington · Accepted Answer · 2017-04-06 15:51:46Z

2

With Core Data you fetch only one entity type at a time. Core Data isn't SQL.

The Core Data style approach to this would be something like: Fetch instances of Patients. Then use the sounds relationship on each Patients instance to get information about which recordings exist. For example, if you want to know if a specific patient has recordings, look at the sounds relationship-- which is a set-- and see if it's empty.

answered Apr 6, 2017 at 15:51

Tom Harrington

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1 Comment

Imran Over a year ago

@Robotic Cat thanks for the edited question. I will surely check the rules about asking questions next time i come here. Thanks.

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