RealmSwift query API gives Query<Date> instead of Date

I'm using RealmSwift to query for appointments on a specific day, so the method looks like:

func appointments(on date: Date) -> [Appointment] {
    realm.objects(Appointment.self)
        .where {
            Calendar.current.isDate($0.date, inSameDayAs: date)
        }
        .map { $0 }
}

But there are two issues:

1. Cannot convert value of type 'Query<Date>' to expected argument type 'Date'. Looks like the date property from Realm object is a Query<Date> instead of Date, how do I get the actual date from it?
2. Cannot convert value of type 'Bool' to closure result type 'Query<Bool>'. So realm expects a Query<Bool> instead of Bool, which isn't what I read on Realm's website regarding the query API: https://www.mongodb.com/developer/products/realm/realm-swift-query-api/

What could possibly be wrong?

Thanks!

Realm queries only supports a subset of operations you can do in normal Swift. See this for a list of things it supports. This is enforced by using the Query<T> type - it only declares the Realm-supported operations, like comparison operators, boolean operations, in for collections, etc. You can't pass a Query<T> around, as if it were a normal T.

Determining whether a date is in the same day as another date is not one of the supported operations. What you can do instead is find the beginning and end of date, and use comparison operators to check if the object's date is between them.

let calendar = Calendar.current
let start = calendar.startOfDay(for: date)
let end = calendar.date(byAdding: DateComponents(day: 1), to: start)

.where { $0.date >= start && $.date < end }

There's an excellent answer by @sweeper. Another option is store the date also as a string as another object property.

So the Realm object would look like this

class ApptClass: Object {
  @Persisted var timestamp: Date!
  @Persisted var dateString = ""

  convenience init(withDate: Date) {
     self.init()
     self.timeStamp = withDate
     //get the date as a YYYY-MM-DD formatted string
     self.dateString = convertDateToDateString(d: withDate) //need to create this func
}

from there you can then do direct queries for specific dates

let results = realm.objects(ApptClass.self).where { $0.dateString == "2023-08-09" }

Edit: Per a note from @JoakimDanielson

> And you also need to make sure you update this property if the date
> changes

which, and one option, could be accomplished by using an unmanaged computed var that's backed by the timeStamp an dateString var. Something like this pseudo code

class ApptClass: Object {
      @Persisted var timestamp: Date!
      @Persisted var dateString = ""
      var useThisToSetTheDate: Date {
         set {
            set the timeStamp and the dateString
         }
         get {
            return timestamp
         }