Fastest Way of Populating Combobox With Large Amount Of Data

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I am writing a database application in which i have to load about a thousand list of items from the database into a combobox. The retrieving and the population of the data into the combobox is done successfully using the

foreach

loop. But the problem is that it takes too long a time for the populating of the combobox to get completed because of the large list of items to populate.

Can any folk help me with an idea about how to populate the combobox in the fastest way possible? I will be very thankful for that. Thank you.

Posted 8-Mar-12 1:32am

BBAzar

Updated 28-Jun-18 0:11am

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4 solutions

Solution 4

Either use Items.AddRange[^] to add all the items at the same time, or wrap your loop in BeginUpdate[^]/EndUpdate.

Edit: but indeed, this is way too many items to put in a dropdown, you should use an auto-completing textbox or something similar instead.

Posted 8-Mar-12 3:51am

BobJanova

v2

Solution 2

Thousand is not a big number. Ideally it should not take long to process them. Are you sure it is the loop that takes so much time?

Posted 8-Mar-12 2:26am

dan!sh

Comments

BobJanova 8-Mar-12 9:49am

If it's causing a UI refresh each time, it certainly can be.

Solution 1

In stead of ForEach, you can try Parallel.ForEach in System.Threading.Tasks namespace.

C#

Parallel.ForEach

Here is the sample code:

C#

IEnumerable<string> items = ...

Parallel.ForEach(items, item => {
   ...
});
</string>

Posted 8-Mar-12 1:37am

Ganesan Senthilvel

Comments

BobJanova 8-Mar-12 9:49am

This will not help at all for updating a UI control.

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This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Pete O'Hanlon · Accepted Answer · 2012-03-08T02:37:00

Solution 3

Rather than explicitly loading the data into the combo box an item at a time, why don't you bind the data to it once you've retrieved it. This is generally a lot more efficient.

However, is there a reason you need to display that many items. In my experience, users will not want to wade through that many items to find one that they want. Rather than loading 1000 items, why not provide AutoComplete instead?

Posted 8-Mar-12 2:37am

Pete O'Hanlon

Comments

Dylan Morley 8-Mar-12 9:48am

Totall agree with your second paragraph - 1000 is far too many to be displaying in a drop down list.

For the benefit of the OP, here's the only thing I could quickly find on the subject
http://www.ixda.org/node/19338

Notice people are saying you shouldn't have more than 12 \ 30 etc?

There are better ways to display data than drop down lists when working with larger sets of data. Drop down lists are best suited for a small selection of possibilities.

AutoComplete is certainly a way to go :)

Fastest Way of Populating Combobox With Large Amount Of Data

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Fastest Way of Populating Combobox With Large Amount Of Data

4 solutions

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