SwiftData Predicate crash: can't use NULL on left hand side

Question

Every time I run the predicate I get an error
xCode version 15.3
Destination macOS Sonoma, 14.4
Swift 5

@AppStorage(UserDefaults.Constants.selectedFilterName) static var selectedFilterName: String?
@Query(filter: #Predicate<Filter> {
    $0.name == (selectedFilterName ?? "")
}) var selectedFilters: [Filter]

Model:

@Model
class Filter: Hashable, Identifiable {
    var id: String { name }
    let name: String
}

Stack:

can't use NULL on left hand side
(
    0   CoreFoundation                      0x000000019c17eccc __exceptionPreprocess + 176
    1   libobjc.A.dylib                     0x000000019bc66788 objc_exception_throw + 60
    2   CoreData                            0x00000001a29cb744 -[NSSQLGenerator newSQLStatementForRequest:ignoreInheritance:countOnly:nestingLevel:nestIsWhereScoped:requestContext:] + 4040
    3   CoreData                            0x00000001a29ca62c -[NSSQLiteAdapter newSelectStatementWithFetchRequestContext:ignoreInheritance:] + 140
    4   CoreData                            0x00000001a29ca564 -[NSSQLFetchRequestContext _createStatement] + 52
    5   CoreData                            0x00000001a29ca34c -[NSSQLFetchRequestContext fetchStatement] + 172
    6   CoreData                            0x00000001a29ca22c -[NSSQLFetchRequestContext executeRequestCore:] + 28
    7   CoreData                            0x00000001a29c9e94 -[NSSQLStoreRequestContext executeRequestUsingConnection:] + 300
    8   CoreData                            0x00000001a29c9bbc __52-[NSSQLDefaultConnectionManager handleStoreRequest:]_block_invoke + 60

when your predicate depends on a property wrapped value usually you need to create use a false predicate and then set the real predicate that uses the value at top of body. That was the case for @FetchRequest I'm not certain for @Query though. — malhal
– malhal, Commented Mar 16, 2024 at 14:03
FetchRequest uses NSPredicates, that ask Filter to be inherited from NSObject and being NSManagedObject. I'd like to avoid this as I don't really understand how it would work with @Model :[ I'll try to set the real predicate in the body anyway but now without FetchRequest if it possible — murabye
– murabye, Commented Mar 16, 2024 at 14:13
You misunderstood what mahal meant, he was only comparing to FetchRequest not saying you should use it. You can not use anything related to Core Data when using SwiftData. I believe he meant you should do something similar to what I did in the last part of this answer — Joakim Danielson
– Joakim Danielson, Commented Mar 16, 2024 at 14:20

murabye · Accepted Answer · 2024-03-16 14:31:19Z

0

@JoakimDanielson and @malhal - thanks!
Answer is: @Query(filter: Predicate<Filter>.false) var selectedFilters: [Filter]

init() {
    selectedFilterName = ""
    var fetchDescriptor = FetchDescriptor<Filter>(predicate: #Predicate { $0.name == (selectedFilterName ?? "") })
    fetchDescriptor.fetchLimit = 1
    _filters = Query(fetchDescriptor)
}

answered Mar 16, 2024 at 14:31

murabye

1051 silver badge8 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

SwiftData Predicate crash: can't use NULL on left hand side

1 Answer 1

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related