Using Asp.net Datagrid to retrieve and display data is a quick and easy process, and .NET offers many features to customize its look and performance. The one thing that's not commonly known is that .NET gives developers the ability to search within Datagrid results, or drilldown and filter within the data until they find what they're looking for.
With all the search engines available, more often than not, a search will return more results than necessary. This is why many leading Websites, such as Microsoft, offer users the ability to search within results. This saves users from repeating their search with altogether different criteria, in order to find something specific within a broad category of results.
In this article I'll show you how to perform this kind of drilldown data searching using the Datagrid. .NET offers two methods to filter data. One is the Dataset's Dataview Rowfilter property that we'll be using here. The is the Datatable's Select command, but, as this doesn't support features like the paging, etc. of a Datagrid, we'll won't focus on this solution here.
As soon as a user enters a search term into our main search field and submits it, our Page_Load subroutine will be prompted to confirm the submission. Next. It will determine whether there are any existing sessions that we'll need to clear before we work with a new result set. After this, it makes sure our Datagrid is reset to page 1, before it finally calls our data access subroutine -- BindGrid() -- to retrieve and display our data, and bring our subsearch textbox into view:
No matter how effective these two methods are in filtering data, you'll soon realize that you won't be able to drilldown search in the way we'd like, because .NET filters only once! In light of this, I'll take .NET's standard filtering one step further, and demonstrate how to drilldown and filter data more than once. Using some simple logic and string concatenation, we'll be able to continuously drilldown and build a new filter string each time within your given result set, until you find the exact thing you're searching for.
So, with all this in mind, let's get to it.
The Initial Search
Our .NET page display, as seen below, has two search fields: the main search box, <input type="text" name="search">, which initializes our main search, and our drilldown search box, <input type="text" name="sub">, for all our subsearches.
Sub Page_Load(Source As Object, E As EventArgs)
If Len(Request ("search")) > 0 Or Len(Request ("sub")) > 0 Then
If Len(Request ("search")) > 0 Then Session.Clear()
MyDataGrid.CurrentPageIndex = 0 'resets the Datagrid to page 1
BindGrid()
subsrch.visible = "true"
Else
subsrch.visible = "false"
End if
End Sub
Now that we've discussed the logic behind this code, we'll fire up our Datagrid drilldown searching via a simple, all-inclusive "select * from all" query that will return to us all available records -- 43 results to be exact -- and enable our subsearch text field, as seen below.
