I am using a telerik radgrid so there are around 5 columns each column edittemplate contains a control along with a required field validator and also a property called AllowMultiRowEdit is set to true so i am able to multiple rows in edit mode.
If any of the values are cleared the for multiple rows I want only those to be validated on update of that particular row.
So i implemented the Grids item data bound event find each and every validator along with the update button and set a unique validation group.
The above implementation most times but fails at some time. Is there any other way of going about this ?
You could use a customvalidator that uses code to check the other textboxes to ensure no value is being updated... requiredfieldvalidator always validates that a value has been supplied in the database, but CustomValidator gives you the ability to control the validation on the client and server. The issue becomes though, how to validate the other controls, and that will be tricky.
You will have to, from within the servervalidate or on the client, navigate up the control hierarchy from the validated control to the row level of the control and then find the other controls in the same row.
Related
I'm trying to create multiple controls by using retrieved data from query, but preventing them from dissapearing on postback, allowing me to get and mantain their values, the problem I have is that I cannot create them on Init because the number of controls, their IDs, and other properties are only known after user selects an item on menu.
Page loads a Menu with all its items and values (Data dependent), plus, a button is loaded too
User clicks a item on menu.
Selected value is used to perform a query by using a Dataset (This happens inside a function which is called from Menu_ItemClick event).
Retrieved data from query is used to determine how many controls must be created (2, 4, 6, etc.). Each control has its unique ID, which is given according to data.
Controls are created and placed into a Panel (named p).
Now controls are visible and available for editing (RadioButtons, TextAreas)
User clicks on button to save information from dynamic controls into a Database
Problems I'm facing
Controls dissapear on postback when clicking button, because they weren't created on Init.
Placing button on UpdatePanel to prevent whole page postback, makes dynamic controls not accesible when trying this:
For Each c In p.Controls
...
Next
The only control it gets is a single Literal control (Controls count is 1), as if other controls didn't exist.
Thank you in advance.
When you wrote "Controls dissapear on postback when clicking button, because they weren't created on Init", did you mean to say that "Controls dissapear on postback when clicking button, because they weren't re-created on Init"? If not, then that is likely a root cause of your problem - dynamically-created controls must always be recreated in response to a PostBack (cf. ASP.NET dynamically created controls and Postback). There may be other issues as well, as dynamic controls in Web Forms can provide a lot of challenges as your scenario gets more involved - here's one article that lays out many of them under various scenarios http://www.singingeels.com/Articles/Dynamically_Created_Controls_in_ASPNET.aspx (e.g., if the user can re-select from the DropDownList to generate a different set of dynamic controls). The canonical reference on all of this is http://msdn.microsoft.com/en-us/library/ms178472.aspx.
Now, on PostBack you'll need some way to ascertain which controls were dynamically created so they can be dynamically re-created. As such, you'll need to store somewhere whatever information allowed you to dynamically create the controls. Since ViewState isn't available in Page_Init and there can be other issues introduced when using sessions, my suggestion is to simply declare a HiddenField that contains that state information. In Page_Init, you'll then need to get the HiddenField's value from Request.Form (since the value of your HiddenField won't be loaded until after Page_Init from ViewState) and go from there to re-create your controls.
My final suggestion: try getting everything working with a regular Panel first and then try and introduce the UpdatePanel - no need to over-complicate the problem at first.
I have a server-side table control. Since I don't know how many rows and columns it will have beforehand, I build the contents of this table in my pages Form_Load event handler.
That works well. But I'm populating that same table with textboxes, and I need to be able to read those textboxes if a submit button is clicked.
As it stands, it appears the table contents are cleared upon postback.
What is the best way to dynamically create textboxes in a table, and then read the values of those textboxes when the page is posted back?
If you want to persist the values on postback you will need to recreate the table control hierarchy on the Page_Init event. This usually means that you will need to rebind your table control to a data structure coming from the database.
Once the control hierarchy is in place, ASP.NET will load any data from the ViewState. This data can be in fact data that was previously set from the server on the textboxes. This step will ensure that these values are preserved on the control.
In the next step ASP.NET will process the POST data, and here basically will update the table textboxes with the input from the client (browser). Any values set from the ViewState will (most probably) be overwritten.
All this happens before Page_Load, so at this stage you should be able to access the client textboxes values.
Check out the ASP.NET Page Life Cycle, especially this image.
I have a aspx page consisting of a calendar button and a textbox.When we click calendar button then a calendar appears and the date which i select on calendar appears in textbox. Now what i want is to load the data from database according to the date selected and allow the user to edit it.And also i want to enable user to add rows at runtime. Do i need to create grid view at runtime?? Can somebody point me in a direction??
You don't need to create the gridview at runtime. You can define the gridview in the markup without having any data initially. You can set the calendar to autopostback and on the server side, capture the new date selected, grab the data based on that date and bind it to your gridview.
As far as editing the data, Gridviews already provide support for this and the amount of code that you need to write largely depends on how the datasource for the gridview is set up. If you use a SQLdatasource with the appropriate settings you practically don't have to write a single line of code besides the markup (Google: Gridview SQLdatasurce editing ASP.net).
I'm creating a custom ASP.Net GridView and I want to be able to alter the __EVENTARGUMENT value but I can't figure out how to capture the returned value on the server side.
I'm creating the ability to have a collapsible representation, so the first level is the standard GridView and I will insert additional rows via JavaScript if they expand the first level row.
My problem is how to create a link on the selecond level rows that posts back with custom data.
I believe the RaisePostBackEvent is where this value gets passed into; the base GridView class allows you to override it, so you should be able to tap into it there.
This is a part of the IPostBackEventHandler interface.
HTH.
Use __dopostback to raise the postback from javascript. Use the correct parameters so that this will be mapped to the right event
Lets say I have three DropDownList controls in a web user control and they depend on each other.
Categories
Brands
Products
Explanation:
After I choose a category from Categories dropdown list, related brands are loaded in Brands DropDownList and same happens when I choose specific brand and they are all located in a web user control since I am using it too much on different pages, I don't want to copy and paste the same code on all the pages.
Problem: The pages can contain a GridView and DataSource control which needs an additional Where parameter to fetch all the data needed in and that parameter could depend on selected product within the Products DropDownList control.
Question: So how can I get that Selected Product Value from Products DropDownList to bind it to SQLDataSource or any other DataSource control.
My Thoughts: I belive I can solve this problem in the ways following.
I can use static variable which is updated once Products selected. That field variable could be public so everyone can reach it
Selected Products DropDownList can create a QueryString Field for me to grap the selected value.
In the same way, the dropdownlist can create a Session variable on the fly and I can fetch the value
It can create a hidden field maybe.
But: Well those are some of my thoughts but I found them so naive to implement. I need something elegant and satisfying to solve this problem. It should be something like a gateway from the Web User Control to outside world.
Maybe a separate class or a Property can help me in the gateway solution.
Anyways, I am waiting for your answers.
If I'm understanding the question correctly:
You can add a property to the user control that exposes the products DDL selected value.
You can also add and raise an event from the user control that fires when the products DDL selected value changes. Creating a custom event argument that contains the product value, allows it to get passed directly to the event handler.
Then your pages can handle the event raised by the user control, have the product value, and bind the grid.
You could bind the DropDownList.SelectedIndexChanged events to the same function, and test the SelectedValue properties of each DropDownList. If their SelectedValues are valid, bind the grid to your DataSource.
I've done this in the past when I needed users to input a certain amount of data before I could query the database. I set the Hidden property on my GridView if the DropDownLists weren't valid, and reset it when they were properly bound.