Dynamic Datagrid - with dynamic columns

Can anyone help with this issue :

I have created an editable dynamic grid with templates and need to update the columns(ie add more or remove columns) in the grid if certain data changes. I have created the datagrid in Sub page_init, but need to add columns when necessary. I think I basically need to know how to call the onInit event from my page when needed to recreated the grid. The onInit should read the data from the dbase and if the are any changes, it will be reflected on the new grid.
Thanks !
Simeon
0
simshp04
6/13/2004 5:42:32 PM
asp.net.presentation-controls 72751 articles. 3 followers. Follow

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You can always call an implementation of the Init event of the page from other places of the page but doing so after the Load event won't make sense - ViewState would already be loaded. You have to re-create all the additional columns before the Load event is run and i suggest you do it in the same place where you create the grid itself.

Cheers
Bug [MCSD]
0
Bug_Bugger
6/14/2004 12:32:25 PM
Thanks for the reply !

I actually discoverd that the grid corrects itself if I bind it when I click a button. I assume that the page_init gets fired and therefore all changes that are in the db are presented correctly in the grid(ie the correct columns are removed or added). I would prefer not to press this button, but rather have changes reflected immediately - and therefore would want to fire a page_init myself rather than have a button doing that job.
So even if the viewstate is loaded surly I could fire an init event and that would just reload everything (from the db) from scratch ?
Just to mention all the columns are in one table and rows in another, I maintain these tables depending on user input - these tables will always represent the grid at any time - I just have to load it into the grid.
Thanks again for your input !
Simeon
0
simshp04
6/14/2004 5:40:41 PM
The only to raise the page_init event is to either request the page from, post the page to itself or use the Response.Redirect from within you code but response.redirect is equivalent of a new page request and Page.IsPostback will be false.

You cannot just magically reset the page and make it start running from scratch from your code and to be honest, i don't see any reason for doing so.
One more thing - what do you mean by ' would prefer not to press this button, but rather have changes reflected immediately...' - pressing a button posts the page to itself which means page is already shown to the user. So how do you envision changes to be immediately reflected - do you mean if someone else changes something then those changes must be reflected on your page? If so, then you need to consider the refresh metatag - it is the only way to make the page refresh periodically and still - this will not be the immediate refresh - http is stateless.

Bug [MCSD]
0
Bug_Bugger
6/15/2004 10:39:27 AM
Hi Nikolai

This dynamic grid is displayed with two other grids – one for columns and one for rows. As the user alters these tables, so the changes are reflected in the dynamic grid. When rows are altered all is well and good as the columns are fixed and the grid does not have to re-create. The problems is when a column is added or removed, the grid has to re-create – and when I said that I need to call page_init, what I should have said was that I needed to do a postback ( I think! Is the page reloaded from scratch each time a postback occurs ?). Perhaps the refresh metatag that you mentioned is what I need - Although not sure how to implement this.
What I understand is that every time I hit the button, that I mentioned in my last post, what was happening, was that the page was been “posted-back” and therefore all was updated.
Do you know of any good articles that would explain the viewstate and how it is created/maintained?
Thanks again
Simeon
0
simshp04
6/15/2004 6:53:50 PM
Sorry, don't have any links related to viewstate but would not help you much here, i guess.

Now, flow of events in your page became clearer but not completely yet. You should understand that something sounds completely logical to you might not to the others. When you are posting the question try to make sure anyone could fully understand it, try to look at your own question from the point of view of the complete outsider.
Now, I've got only tiny bit to clarify here - you say there are 3 grids - main one, one for columns and one for rows. Further you say - 'As the user alters these tables' - i guess you meant grids. Now, how the user alters those grids. For instance, how the user adds a new column to the dynamic grid? - Does he click some kinda 'Add New' button then defines the details the column then hits the save button? You should understand, knowing the whole process flow would greatly simplify the answer.
Now, Postback is a request send to the server using the POST method, i.e. usually click of a button, LinkButton, ImageButton, change of the DropDownList's selected item (if its postback is enabled etc).
Let me try to propose a solution based on my assumptions:
1. I assume your dynamic grid does not have any sorting/paging enabled
2. I assume that after defining a new column user must hit the update button
3. When the updatebutton is hit, you create a definition of the new column and save it somewhere
4. Now, after this happens, simply user Response.Redirect to send the user to the same page again - a new request (not postback) will be initiated and page_init will fire where you will be able to create all the columns in dynamic grid
Refresh metatag will not help you here but will rather annoy your users
There is also another option - to organize the postback, not a new request, after the column update you could emmit the javascript code into the page every time the columns grid is changed. That javascript would post the page to itself and grid would be updated
As you can see, there are few options. If none fits you - explain your process flow fully, to the detail and we'll see.
Cheers
Bug [MCSD]
0
Bug_Bugger
6/16/2004 7:48:05 AM
Your assumptions are indeed correct and so is your answer!

I simply added the Response.Redirect and that sufficed.
Just for clarity, when a page postback occurs are only events like button clicks and DropdownList selected items processed and page events not fired?
Thank you for the help
Simeon
0
simshp04
6/16/2004 7:40:30 PM
Glad you got that sorted but your assumption about the postback is not fully correct though. When postback occurs, all the events that would run for the first time request would fire plus an event handler of the control that caused the postback will fire too (given one is provided) so, in effect, postback is a superset of the usual request.

Cheers
Bug [MCSD]
0
Bug_Bugger
6/17/2004 8:12:01 AM
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