How to avoid "Key paths that include an array property must use aggregate operations" exception when querying a Realm? - swift

Question

I have a Realm object database with the following structure:
class ItemModel: Object {
dynamic var id: Int = 0
dynamic var catId: Int = 0
dynamic var subId: Int = 0
dynamic var itemName: String = ""
dynamic var sortOrder: Int = 0
dynamic var favorite: Bool = false
override static func primaryKey() -> String {
return "id"
}
}
class SubCategoryModel: Object {
dynamic var id: Int = 0
dynamic var catId: Int = 0
dynamic var subCatName: String = ""
dynamic var desc: String = ""
dynamic var sortOrder: Int = 0
let haveUnit = List<ItemModel>()
override static func primaryKey() -> String {
return "id"
}
}
class CategoryModel: Object {
dynamic var id: Int = 0
dynamic var catName: String = ""
dynamic var sortOrder: Int = 0
override static func primaryKey() -> String {
return "id"
}
}
To query the database I'm using the following code:
var data = List<ItemModel>()
let index = indexPath.section
var query = "catId == \(inCategory)"
if (searchTextValue != "") {
query += " AND itemName CONTAINS[c] \(searchTextValue)"
}
if index == 0 {
let unitFavorite = DBManager.realm.objects(ItemModel.self).filter("\(query) AND favorite == true")
data += unitFavorite
} else {
var subquery = "catId == \(inCategory)"
if (searchTextValue != "") {
subquery += " AND ANY haveUnit.itemName CONTAINS[c] %#"
let subCat = DBManager.realm.objects(SubCategoryModel.self).filter(subquery, searchTextValue).sorted(byKeyPath: "sortOrder", ascending: true)
data += subCat[indexPath.section - 1].haveUnit
} else {
let subCat = DBManager.realm.objects(SubCategoryModel.self).filter(subquery).sorted(byKeyPath: "sortOrder", ascending: true)
data += subCat[indexPath.section - 1].haveUnit
}
}
When running this code I'm always seeing the following exception:
Terminating app due to uncaught exception 'Invalid predicate', reason: 'Key paths that include an array property must use aggregate operations'
Can you please help me understand why I'm seeing this exception and what I can do to avoid it?