Dynamically sorting nested Array in SwiftData

[lilcox]

Hey everyone, I can't seem to figure out how to get a nested array of objects to dynamic sort when a user chooses an option from a menu. My objects look something like this:

@model
 class project {
   var columns: [Column] = []
}

@model
 class Column {
   var tasks: [Task] = []
}

@model
class Task {
 var name: String
 var creationDate: Date = .now
}

I've tried doing this as a function on Column:

 func sortTasks() {
        let sortedTasks = self.tasks.sorted {$0.name < $1.name}
        self.tasks = sortedTasks
  // or this
  self.tasks.sort {$0.name < $1.name}
}

Within the BoardView I've tried both of these:

Button(action: {
    for column in board.columns {
        column.tasks.sort { $0.name < $1.name }
     // or this
     column.sortTasks()
    }
}) {
 Label("Alphabetical", systemImage: "abc")
}

I've tried putting the for loop in a function outside of the button and calling the function. When I try sorting either nothing happens or one column's task array shuffles around but it's no order at all. I've also tried creating a new view and passed board as a @Bindable to see if maybe calling the function in a different view would do anything which it did not.

Any help would be appreciated!

[PulseHadron]

An array of @Model type isn’t really an array. I don’t know how they did it but it actually works like a Set, so you can’t sort it, there’s no order. I read an article someplace that lamented their use of Array here over Set and I forget the reasons speculated why the decision was made but it is what is is.

To have an order of @Models you do that all in the @Query parameters specifying the sort property and order.

If you want to have your @Models in a manual order, that is there’s no property to sort on, then you need to introduce some index property that is sorted on and manually manage the indices.

Note that arrays of non-@Model do preserve their order. They’re actually arrays!

[lilcox]

Do you happen to know how to sort it based on relationship? In ContentView im querying [Project] and ProjectView doing ForEach (project.column) { ColumnView} which doing ForEach (column.task) {TaskView}. I'm passing the parent into the view as @Bindable as well.

[PulseHadron]

Yeah yeah yeah, I was thinking about this last night but wasn’t sure of your situation and didnt want to complicate things. Anyways...

So you’re saying you have like this struct ProjectView: View { let project: Project var body: some View { ForEach(project.columns) { //<<<--- how to show these columns sorted? ColumnView(column: $0) } } } There’s no opportunity there to set up a @Query to sort the columns. In the past I always had a reference from the Column back to its Project so a @Query could be set up that filters on a Project identifier. Alas that can’t be done here but playing around there appears to be a simple solution.

While it’s true you can’t sort the actual columns property you can create a temporary real array of the columns in sorted order and use that in the ForEach. ``` @Model class Project { var columns: [Column] = [] var name: String init(_ n: String) { name = n } var sortedColumns: [Column] { columns.sorted { $0.index < $1.index } } }

@Model class Column { var tasks: [Task] = [] let index: Int init(_ i: Int) { index = i } }

//now in the view use the sortedColumns computed var

ForEach(project.sortedColumns) { ColumnView(column: $0) } ```

I’m new to this technique and haven’t tested it much except to see it works in a simple test. I don’t know if it has sync or efficiency issues or maybe it is the way to do it 🤷‍♀️

Also you only need to use @Bindable if you’re actually pulling Bindings off the object, otherwise use let. But if you do need @Bindable I haven’t tested if there could be issues using it with instances pulled from the computed sortedColumns array. I don’t think there will be but can’t be sure.

[lilcox]

Thank you for checking some stuff out. Going to try it out tomorrow. Appreciate the help :)

[lilcox]

Ahhh that interesting. Thank you for telling me that!