仅在用户提交表单后如何显示EmptyDataText？

Question

I just created a basic ASP.NET website using Microsoft's walkthrough here . It has one page with a form that takes in some text input, runs a database query based on that, and results the results in a GridView . I added the EmptyDataText property to my GridView to explicitly show users when their search returns no results.

It all works as expected with one exception:

IIS shows my EmptyDataText of "No results found." even before the search form is submitted.

This defeats my purpose behind using EmptyDataText , which is to indicate to the user that the webpage successfully submitted their search but found no results, as opposed to took their search and threw it into the ether.

For example, a user who searches for something that cannot be found will see "No results found." both before and after their search, as opposed to nothing before and "No results found." after. The former behavior gives the impression that the search didn't work.

How can I configure my GridView to show the EmptyDataText only after the search form is submitted?

Answer 1

you are using sqldatasource that will bind automatically while loading the page. Bind the gridview programatically while clicking the search button

Answer 2

Don't bind your GridView until after the user has initiated a search. When you bind your GridView with a datasource that has 0 records, then the EmptyDataText will be displayed.

Chances are that you are binding it on Page_Load.

EDIT

Wherever a DataBind() is performed in your code (other than the action handler), remove it. Your DataBind() should only occur in the handler that receives the user action.

If Visual Studio is doing some voodoo behind the scenes with automatic binding, you can always default the grid to invisible. Make it visible when the user initiates a search.

Answer 3

Just don't databind it before the search, it will effectively be completely invisible until then.

UPDATE: maybe you are using a DataSourceID (which databinds automatically)?

UPDATE 2: First off, for what ever reason was the downvote (at least have a decency to leave a comment)? If it weren't for me the OP would still not have known where the problem lies - and secondly, just remove the DataSourceID property from the declaration, and set it back from codebehind when the user makes a search (you might want to call the GridView DataBind() method manually after that, but only if it doesn't do that on its own - try it without first).

Answer 4

As the other answers suggested, the GridView is being bound before the user makes a search because it has a DataSourceID attribute. As explained on MSDN , this attribute causes the GridView to automatically bind to the specified source:

To bind to a data source control, set the DataSourceID property of the GridView control to the ID value of the data source control. The GridView control automatically binds to the specified data source control and can take advantage of the data source control's capabilities to perform sorting, updating, deleting, and paging. This is the preferred method to bind to data.

To get the behavior I was looking for, I removed that attribute from the GridView and instead added an OnClick attribute to the submit button for my search form. The OnClick attribute refers to a method BindGridView that gets called only when the user submits the form.

All this method does is populate the DataSourceID with the same value it had before as an attribute:

public void BindGridView(object sender, EventArgs e)
{
    GridView1.DataSourceID = "DataSourceID1";
}