Duplicate items in List

[iDevPro]

Describe the bug

Hello @david-swift I found strange issue with List, the Item is duplicated

To Reproduce

I want get "load more" functionality, after load next portion of content i modify list like this:

@State var items: [Item] = []

func loadMore() {
    
    // fetch and decode here
    
    Idle {
             var items = self.items
             let loadMoreIndex = items.lastIndex(where: { $0.id == "load-more" })! // ! for simplify construction here 
             self.items.insert(contentsOf: fetchedItems, at: loadMoreIndex) // for insert at the end but before load more item
    }
}

Current behavior:

• items contains one object with id "load-more"
• list contains two view with text "Load more..."

Expected behavior

• items contains one object with id "load-more"
• list contains one view with text "Load more..."

Additional context

No response

[david-swift]

I'm not able to reproduce this and it looks like unexpected behavior, so I'd be very happy if you could provide more details about the situation it occured.

As far as I understand your idea, what you're trying to accomplish could be accomplished in a cleaner way using a computed property combined with the state property:

@State private var items: [Item] = []

var allItems: [Item] {
    items + [id: "load-more")]
}

var view: Body {
    List(allItems) { item in
        switch item.id {
            case "load-more":
                // Load more view
            default:
                // Other views
        }
    }
}

func loadMore() {
    // ...
    items += fetchedItems
    // ...
}

It may help looking at https://github.com/AparokshaUI/adwaita-swift/pull/37#issuecomment-2187911876 for more information about state. In general, if state management is complex, there's probably a simpler, more elegant solution. You can always open a discussion if you have questions! And I'll definitely improve the docs to mention those concepts at some point.