Master Data - Following Keys

Question

I am new to Core Data and stumbled on the correct way to configure the query.

My managed object model includes the Apartment, Lease classes, and what I would otherwise call a join table called ApartmentLease. It looks like this:

/-----------------\      /-----------------\      /-----------------\
| Apartment       |      | ApartmentLease  |      | Lease           |
|-----------------|      |-----------------|      |-----------------|
| number          |      | startOn         |      | occupantName    |
|-----------------|      | endOn           |      | monthlyRate     |
| apartmentLeases |-\    |-----------------|      | occupantPhone   |
\-----------------/  \->>| apartment       |      |-----------------|
                         | lease           |<<----|apartmentLeases  |
                         \-----------------/      \-----------------/

So, I tried to simulate that Leasing can have many apartments, and each apartment for rent has its own start and end dates.

So my question is: Given the date range, how can I request the Apartment object and return an array of all the leases that occupied the Apartment during this date range?

Thank you and sorry for my awful ASCII art!

Bert

Answer 1

"" "ApartmentLease".

[NSPredicate predicateWithFormat:@"startOn <= %@ && endOn >= %@", referenceDate, referenceDate];

, ApartmentLease, :

NSArray *apartments = [apartmentLeaseArray valueForKeyPath:@"@distinctUnionOfObjects.apartment"];

, .

, , . NSFetchRequest, . Core Data , . , , .

Answer 2

Marcus S. Zarra , . Core Data .

, . ApartmentLease , , . .

. . , , .

:

Apartment {
    number:int;
    leases<--(optional,cascade)-->>lease.apartment
} 

Lease{
    startOn:date;
    endOn:date;
    occupantName:string;
    monthlyRate:float;
    occupantPhone:string
    apartment<<--(required,nullify)->Apartment.leases
}

Apartment.leases .

NSManageObject *anApartment= // which every apartment whose leases you want to examine
NSPredicate *rangePred=[NSPredicate predicateWithFormat:@"startOn <= %@ && endOn >= %@", startReferenceDate, endReferenceDate];
NSSet *leases=[anAparment valueForkey:@"leases"];
NSSet *leasesInDateRange=[leases filteredSetUsingPredicate:rangePred];

, , , NSManagedObject , . , bool : inForce, . :

-(BOOL) inForce{
    BOOL isInForce;
    NSDate *today=[NSDate now];
    if (self.starOn<today<self.endOn){
        isInForce=YES;
    }else{
        isInForce=NO;
    }
    return isInForce;
}

, , ForForce, , , .