# How to show only pre-selected items from local database in dataviewer-list/-grid? **URL:** \ **Category:** Questions about Thunkable X\ **Tags:** beginner\ **Created:** [June 14, 2021, 10:25pm UTC](https://community.thunkable.com/t/how-to-show-only-pre-selected-items-from-local-database-in-dataviewer-list-grid/1344987 "2021-06-14T22:25:07Z")\ **Posts on this page:** 16\ **Page:** 1
**Author:** ![limogopy64fbb](https://avatars.discourse-cdn.com/v4/letter/l/90db22/32.png) [@limogopy64fbb](https://community.thunkable.com/u/limogopy64fbb)\ **Post date:** [June 14, 2021, 10:25pm UTC](https://community.thunkable.com/t/how-to-show-only-pre-selected-items-from-local-database-in-dataviewer-list-grid/1344987/1 "2021-06-14T22:25:07Z")
to every row of my database i have a “datafield” named “seleced” - with this “flag =0/1)” i want to “select” or “deselect” each item before showing it in a dataviewer-list / -grid. ![item_selected](https://us1.discourse-cdn.com/flex015/uploads/thunkable/original/3X/b/3/b3f6c79d3823346955170ec6c9407138f9dddc40.jpeg) how do i have to code this with blocks, that only items with flag = 1 are shown in dataviewer-list / - grid? many thanks in advance for every proposal! ---
**Author:** ![tatiang](https://sea1.discourse-cdn.com/flex015/user_avatar/community.thunkable.com/tatiang/32/55482_2.png) [@tatiang](https://community.thunkable.com/u/tatiang)\ **Post date:** [June 14, 2021, 10:51pm UTC](https://community.thunkable.com/t/how-to-show-only-pre-selected-items-from-local-database-in-dataviewer-list-grid/1344987/2 "2021-06-14T22:51:49Z")
Data Viewer Lists can only show the entire contents of a data source. So in order to filter them, you have to duplicate the data source and filter it. You can have a second data source where you delete all rows and then create rows and populate them from the data in your original data source but only if a condition is true (selected = 1). You’ll need to loop through the original data source to do this. ---
**Author:** ![limogopy64fbb](https://avatars.discourse-cdn.com/v4/letter/l/90db22/32.png) [@limogopy64fbb](https://community.thunkable.com/u/limogopy64fbb)\ **Post date:** [June 15, 2021, 6:46am UTC](https://community.thunkable.com/t/how-to-show-only-pre-selected-items-from-local-database-in-dataviewer-list-grid/1344987/3 "2021-06-15T06:46:44Z")
many thanks for your advice - it saves me very much time! ---
**Author:** ![muneer](https://sea1.discourse-cdn.com/flex015/user_avatar/community.thunkable.com/muneer/32/75210_2.png) [@muneer](https://community.thunkable.com/u/muneer)\ **Post date:** [June 15, 2021, 7:07am UTC](https://community.thunkable.com/t/how-to-show-only-pre-selected-items-from-local-database-in-dataviewer-list-grid/1344987/4 "2021-06-15T07:07:30Z")
Check this [https://x.thunkable.com/projectPage/5fb9fb1dbfeb240011084d78](https://x.thunkable.com/projectPage/5fb9fb1dbfeb240011084d78) ---
**Author:** ![codeswept](https://sea1.discourse-cdn.com/flex015/user_avatar/community.thunkable.com/codeswept/32/87755_2.png) [@codeswept](https://community.thunkable.com/u/codeswept)\ **Post date:** [June 15, 2021, 7:09am UTC](https://community.thunkable.com/t/how-to-show-only-pre-selected-items-from-local-database-in-dataviewer-list-grid/1344987/5 "2021-06-15T07:09:39Z")
![image](https://us1.discourse-cdn.com/flex015/uploads/thunkable/original/3X/7/7/7725bf82d7521cd5a869625d0686314c32e2ace1.png) I do this, but it is quite slow as I have 40 rows. ---
**Author:** ![muneer](https://sea1.discourse-cdn.com/flex015/user_avatar/community.thunkable.com/muneer/32/75210_2.png) [@muneer](https://community.thunkable.com/u/muneer)\ **Post date:** [June 15, 2021, 10:21am UTC](https://community.thunkable.com/t/how-to-show-only-pre-selected-items-from-local-database-in-dataviewer-list-grid/1344987/6 "2021-06-15T10:21:49Z")
Yes @codeswept This would be slow for two obvious reasons. - You are evaluating the `list of values` block with every iteration of your loop which means you are reading the database 40 times in your example. - You are retrieving the value of a cell in every iteration which again means reading the database 40 times. **[Edit]** See my version of your code which should run much faster. ![image](https://us1.discourse-cdn.com/flex015/uploads/thunkable/original/3X/5/c/5c8a64e1ae27c9819dabdf4d1279e6477ff535b5.png) ---
**Author:** ![codeswept](https://sea1.discourse-cdn.com/flex015/user_avatar/community.thunkable.com/codeswept/32/87755_2.png) [@codeswept](https://community.thunkable.com/u/codeswept)\ **Post date:** [June 15, 2021, 12:10pm UTC](https://community.thunkable.com/t/how-to-show-only-pre-selected-items-from-local-database-in-dataviewer-list-grid/1344987/7 "2021-06-15T12:10:54Z")
Thank you so much for this! No wonder it was taking 2 minutes to filter my DB each time. ---
**Author:** ![tatiang](https://sea1.discourse-cdn.com/flex015/user_avatar/community.thunkable.com/tatiang/32/55482_2.png) [@tatiang](https://community.thunkable.com/u/tatiang)\ **Post date:** [June 15, 2021, 3:48pm UTC](https://community.thunkable.com/t/how-to-show-only-pre-selected-items-from-local-database-in-dataviewer-list-grid/1344987/8 "2021-06-15T15:48:40Z")
Yep, switching from a `stored` variable to an `app` variable is also going to be faster. If you need to use a `stored` variable, assign its value to an `app` variable before using the `app` variable in the loop. ---
**Author:** ![codeswept](https://sea1.discourse-cdn.com/flex015/user_avatar/community.thunkable.com/codeswept/32/87755_2.png) [@codeswept](https://community.thunkable.com/u/codeswept)\ **Post date:** [June 15, 2021, 4:09pm UTC](https://community.thunkable.com/t/how-to-show-only-pre-selected-items-from-local-database-in-dataviewer-list-grid/1344987/9 "2021-06-15T16:09:25Z")
Great, thanks for the suggestions! ---
**Author:** ![limogopy64fbb](https://avatars.discourse-cdn.com/v4/letter/l/90db22/32.png) [@limogopy64fbb](https://community.thunkable.com/u/limogopy64fbb)\ **Post date:** [July 1, 2021, 11:26am UTC](https://community.thunkable.com/t/how-to-show-only-pre-selected-items-from-local-database-in-dataviewer-list-grid/1344987/10 "2021-07-01T11:26:53Z")
Thank you very much for your version - i tried to test it out but could not succeed, i build an item\_list with 5 datasets (see screenshot) ![item_list](https://us1.discourse-cdn.com/flex015/uploads/thunkable/original/3X/7/4/74d505b20c7b998fa8a9a4eed48e8d91dfba3b44.jpeg) with blocks i want to “deselect” one dataset (= “duck”) ot my itemList … ![blocks](https://us1.discourse-cdn.com/flex015/uploads/thunkable/original/3X/c/7/c7ab1c60535d2269dedfbe9027180cefb7b7cf23.jpeg) but it shows me all datasets of my item\_list ![dataViewerList](https://us1.discourse-cdn.com/flex015/uploads/thunkable/original/3X/f/8/f87c791794418540941b2c3cd304789584cfc1db.jpeg) many thank in advance for your help! ---
**Author:** ![muneer](https://sea1.discourse-cdn.com/flex015/user_avatar/community.thunkable.com/muneer/32/75210_2.png) [@muneer](https://community.thunkable.com/u/muneer)\ **Post date:** [July 1, 2021, 1:19pm UTC](https://community.thunkable.com/t/how-to-show-only-pre-selected-items-from-local-database-in-dataviewer-list-grid/1344987/11 "2021-07-01T13:19:57Z")
Have you tested it on your mobile? ---
**Author:** ![limogopy64fbb](https://avatars.discourse-cdn.com/v4/letter/l/90db22/32.png) [@limogopy64fbb](https://community.thunkable.com/u/limogopy64fbb)\ **Post date:** [July 1, 2021, 2:02pm UTC](https://community.thunkable.com/t/how-to-show-only-pre-selected-items-from-local-database-in-dataviewer-list-grid/1344987/12 "2021-07-01T14:02:56Z")
yes, i test it with thunkableApp on my iphone 12 and on android tablet, same result - all 5 items are dsplayed … ---
**Author:** ![limogopy64fbb](https://avatars.discourse-cdn.com/v4/letter/l/90db22/32.png) [@limogopy64fbb](https://community.thunkable.com/u/limogopy64fbb)\ **Post date:** [July 1, 2021, 2:23pm UTC](https://community.thunkable.com/t/how-to-show-only-pre-selected-items-from-local-database-in-dataviewer-list-grid/1344987/13 "2021-07-01T14:23:48Z")
here is link to project … [https://x.thunkable.com/copy/999b2893f211d5d49b767b487e82127a](https://x.thunkable.com/copy/999b2893f211d5d49b767b487e82127a) ---
**Author:** ![muneer](https://sea1.discourse-cdn.com/flex015/user_avatar/community.thunkable.com/muneer/32/75210_2.png) [@muneer](https://community.thunkable.com/u/muneer)\ **Post date:** [July 1, 2021, 3:36pm UTC](https://community.thunkable.com/t/how-to-show-only-pre-selected-items-from-local-database-in-dataviewer-list-grid/1344987/14 "2021-07-01T15:36:47Z")
check this ![image](https://us1.discourse-cdn.com/flex015/uploads/thunkable/original/3X/0/7/070ea161d8d9f78be63a9e0fb94ab86bd39add29.png) I made it highlight the line but the logic is the same. ---
**Author:** ![limogopy64fbb](https://avatars.discourse-cdn.com/v4/letter/l/90db22/32.png) [@limogopy64fbb](https://community.thunkable.com/u/limogopy64fbb)\ **Post date:** [July 1, 2021, 8:55pm UTC](https://community.thunkable.com/t/how-to-show-only-pre-selected-items-from-local-database-in-dataviewer-list-grid/1344987/15 "2021-07-01T20:55:32Z")
i replace your “higlight the line” with "set Data\_Viewer\_List1`s LayoutWrapper for … “s Visible to false” and now it works fine … thank you so much! ---
**Author:** ![ioannis](https://sea1.discourse-cdn.com/flex015/user_avatar/community.thunkable.com/ioannis/32/146956_2.png) [@ioannis](https://community.thunkable.com/u/ioannis)\ **Post date:** [November 8, 2024, 1:20pm UTC](https://community.thunkable.com/t/how-to-show-only-pre-selected-items-from-local-database-in-dataviewer-list-grid/1344987/16 "2024-11-08T13:20:17Z")