How can we prevent Rad Autocomplete from accepting Duplicate entry?

Depends on your approach.

If you just don't want that a duplicated token be added it's quite easy: just keep a token array and check the new entry against the array in the EntryAdded event. If it already exists in the array ignore the new entry, otherwise add it to the array.

Now if you don't want that an existent token even show up in the list you may implement a control of your tokens by adding subsequent WHERE clauses to your query in order to ignore the specific tokens.

If you want the behavior above but you are not using a SQL query to populate your list - instead you're using a hard coded list - you can directly delete the used token from the list.

Just don't forget that in case of user delete one or more tokens, you have to remove it from your control array and put it back to the list by removing the respective WHERE clause (if using a SQL query) or inserting it back in your hard coded list.

Good luck!

Hello, Yan,    

Thank you for sharing your idea wit he community.

However, I would like to note that the EntryAdded event is not relevant for RadAutoCompleteBox from the Telerik UI for WinForms suite since this forum thread is related to the WinForms autocomplete box. 

Note that we already have a feature request for introducing a mode which will control whether duplicated entries will be allowed or not. You can track its progress, subscribe for status changes and add your comments on the following link : https://feedback.telerik.com/winforms/1372559-add-radautocompletebox-mode-disabling-the-selection-of-already-selected-items 

It also contains a sample approach how to achieve such functionality in RadAutoCompleteBox.

I hope this information helps. If you need any further assistance please don't hesitate to contact me. 

Regards,
Dess | Tech Support Engineer, Sr.
Progress Telerik

Hello, any news about this topic?

I need to exclude already present items from the RadAutoCompleteBox.

L.

Hello, Luigi,

As of R1 2020 SP1 RadAutoCompleteBox offers the AllowDuplicates property. It controls whether already selected items can be suggested.

Note that you can still add duplicated tokens in the editor if you type them manually. In order to avoid that you can subscribe to TokenValidating event and if the existing text in RadAutoCompleteBox contains the new text, set the IsValidToken property to false. 

private void RadAutoCompleteBox1_TokenValidating(object sender, TokenValidatingEventArgs e)
{
    if (this.radAutoCompleteBox1.Text.Contains(e.Text))
    {
        e.IsValidToken = false;
    }
}

I hope this information helps.

Regards,
Dess | Tech Support Engineer, Sr.
Progress Telerik

I don't have the TokenValidating option in the HTML tags of my AutoCompleteBox.

How can I solve this? 

(PS: I'm using VB.NET as language). 

L.

Hi, Luigi,

I would like to note that this forum is related to RadAutoCompleteBox from the Telerik UI for WinForms suite. However, it seems that you are not using the WinForms product.

Feel free to post any technical inquiries in the relevant forum: https://www.telerik.com/forums Thus, the appropriate community would gladly assist you.

Thank you for your understanding.

Regards,
Dess | Tech Support Engineer, Sr.
Progress Telerik

Is it possible to update at version 2020 only the RadAutoCompleteBox component? 

Ah, ok, sorry Dess. 
I'll try in the appropriate forum. 

L.