ControlFreak
LANGUAGES: VB.NET | C#
ASP.NET VERSIONS: 2.x
Search Box
Master the Art of Search with this Custom Control that Provides the Ability to Search Your Site, Other Sites, or the Entire Web
By Steve C. Orr
Every respectable Web site of significance needs to provide search capabilities so users can quickly find the information they seek. But how does a Web developer provide such functionality? There are myriad ways one might go about this. For example, if all the content is stored within SQL Server, its full text searching capabilities may be of use. But because that s frequently not an option, it s not too difficult to dream about creating a custom system that matches keywords to pages. But why reinvent the wheel? If your Web site is publicly available on the Internet, odds are it has already been thoroughly indexed by Google, MSN Search, and any number of other search engines.
Leave It to the Professionals
The custom SearchBox control I ve created harnesses the power of Google and MSN Search to provide your Web site with all the searching muscle it needs. The SearchBox control, shown in Figure 1, is capable of using a couple different techniques to do the searches, depending on how you configure it.
Figure 1: The SearchBox custom
control can return search results for a specific Web site or the entire Web.
The first and simplest technique builds an appropriate URL string and redirects the user to it. At this point the search is handed off to Google or MSN Search, whichever has been selected in the control s SearchProvider property. For example, if searching the Web for information about towels, the user could be redirected to the following URL:
http://search.msn.com/results.aspx?q=towels
If the user wanted to search only MSDN for information about Babel Fish, this URL could be used:
http://www.google.com/search?q=babel+fish+site%3Amsdn.microsoft.com
Luckily, both Google and MSN Search use similar query strings, so the same code can be used to build the query string no matter which search site is being used.
To use this Firefox-compatible SearchBox control to return search results for a specific site (such as your Web site), set its SearchSiteOnly property to True and set the SearchSite property to the public URL of the Web site. If the SearchSiteOnly property is set to False, the SearchSite property will be ignored and the entire Internet will be searched for the word(s) in the Text property. To allow the users to choose whether they d like to search the entire Web or a specific site, make sure the ShowSearchOptions property is set to True. You can also configure the text that will be displayed for both of these radio buttons with the SearchTheWebText property and the SearchSiteText property.
The ButtonBelow property specifies whether the Search button should appear beside the search TextBox or below it. The ButtonText property lets you configure the text that appears on the button.
All these options to configure the appearance of the control are nice, but you don t even have to show the control to use it. You could set its visible property to False, configure some of the properties described above, and call the SearchBox s Search method to kick off the search.
When the Search button is clicked (or the control s Search method is called) the user will be forwarded to the standard Google or MSN Search Web site with the results immediately displayed, as shown in Figure 2.
Figure 2: One way to use the
SearchBox is to have it redirect the user and their search request to Google s
or MSN Search s standard results page.
This approach works well, and gives the user great results in a hurry. The only downside is that it requires the user to leave your site to get the search results. Web developers that are trying to increase traffic tend to cringe at the thought of sending users away, even if it s just for a quick search that sends them right back into their site. If only there were a good way to get the search results on the server and then output the results into one of your own pages ...
MSN Search Web Services
Luckily, both Microsoft and Google have introduced Web services that we can call to get search results via code. I ve chosen to take advantage of Microsoft s Web service for this version of the SearchBox control because it provides more features than Google s and has less restrictive terms of use. And have you noticed how much MSN Search has improved recently? It looks like Google may have some serious competition in the search arena, after all.
The SearchBox encapsulates the complexities of calling the MSN Search Web Service. If you choose to use this technique, you need to set the SearchBox s SearchProvider property to MSNWebService. You also need to set the MSNApplicationID property to the ID you got free from Microsoft. To get an ID, or to learn more about the MSN Search Web Service, visit http://msdn.microsoft.com/msn/gettingstarted/searchstart/.
Now when the user clicks on the Search button, the control will call the Web service, retrieve the search results, and raise a SearchResultsReady event to the page. A DataTable will be passed as a parameter to this event, allowing you to do whatever you wish with the results. Figure 3 shows a basic page that received search results from a SearchBox control and displayed the results in a GridView control using almost no code:
Protected Sub SearchBox1_SearchResultsReady(ByVal _
SearchResults As System.Data.DataTable) _
Handles SearchBox1.SearchResultsReady
GridView1.DataSource = SearchResults
GridView1.DataBind()
End Sub
Figure 3: This page only required a
couple lines of code to query the MSN Search Web Service and display the
results in a GridView.
Many Web sites prefer to have some kind of search textbox on nearly every page, and then display the results on a specific search page. That s where the PostBackURL property comes in. Set this property to the URL of your special search page; then, in the code behind of that search page, use a couple lines of code to receive the posted values and execute the search:
Protected Sub Page_Load(ByVal sender As Object, _
ByVal e As System.EventArgs) Handles Me.Load
If Request("SearchBox1$text") IsNot Nothing Then
SearchBox1.Text = Request("SearchBox1$text")
SearchBox1.Search()
End If
End Sub
That s about all you need to know to start using the SearchBox control, which is available for download (see end of article for details). An overview of the unique properties, events, and methods are shown in Figure 4. Simply drag the SearchBox.dll into your Visual Studio 2005 toolbox, then drag it onto any Web form(s) and you should be good to go.
|
Unique SearchBox Members |
Description |
|
ButtonBelow property |
This property specifies whether the Search button should appear beside the search textbox or below it. |
|
ButtonText property |
This property specifies the text that should appear on the Search button. |
|
MSNApplicationID property |
Set this to the application id Microsoft gave you. |
|
PostBackURL property |
Set this property to have the control post to another page to display the results. |
|
SearchProvider property |
Set this to Google, MSN, or MSNWebService to use the associated search technique. |
|
SearchSite property |
If you d like to search only one specific Web site (such as your Web site), put the URL of that public Web site into this property. |
|
SearchSiteOnly property |
Set this property to True to only search the site specified in the SearchSite property. |
|
SearchSiteText property |
Set this property to the text that you d like to be displayed for the Search This Site radio button. |
|
SearchTheWebText property |
Set this property to the text that you d like to be displayed for the Search The Web radio button. |
|
ShowSearchOptions property |
Set this property to True to display the radio buttons, or False to hide them. |
|
SearchResultsReady event |
This event provides a DataTable filled with the results from the MSN Search Web Service. |
|
Search method |
Call this method to initiate the search without requiring the Search button to be clicked. |
Figure 4: The SearchBox control provides a dozen members to make searching quick and easy.
So How Does It Work?
The SearchBox is a custom Web server control. The easiest way to create a custom Web server control is to first create a Web Control Library. This may not be as easy as it sounds if you ve recently upgraded to Visual Studio 2005, because Microsoft moved things around quite a bit. As you can see in Figure 5, the option for a Web Control Library can be found under the Windows category beneath your language of choice. Not a very intuitive place to put it, in my opinion, but it s easy enough to find once you know where it is.
Figure 5: The Web Control Library
project type is now located under the Windows category in the Visual Studio
2005 New Project dialog box.
The SearchBox class inherits from WebControl and implements INamingContainer. Composition is used for this control (instead of Rendering), meaning essentially that, internally, controls are instantiated from within the CreateChildControls event. The source code for most of the properties is fairly boilerplate, so I ve only listed a few of the more interesting ones in Figure 6.
Description("Shows/Hides the search option radio
buttons"), _ DefaultValue(True)> _ Public Property ShowSearchOptions() As Boolean Get If
ViewState("ShowSearchOptions") IsNot Nothing Then Return _ Convert.ToBoolean(ViewState("ShowSearchOptions")) Else Return True
'default End If End Get Set(ByVal value As
Boolean) ViewState("ShowSearchOptions") = value End Set End Property Public Enum SearchProviderEnum MSN = 0 Google = 1 MSNWebService = 2 End Enum Dim _spe As SearchProviderEnum Description("Which search method to use")> _ Public Property SearchProvider() As SearchProviderEnum Get Dim s As String =
CStr(ViewState("SearchProvider")) If s Is Nothing
Then Return _spe Else Select Case
Convert.ToInt32(s) Case 0 Return
SearchProviderEnum.MSN Case 1 Return
SearchProviderEnum.Google Case 2 Return
SearchProviderEnum.MSNWebService End Select End If End Get Set(ByVal value As
SearchProviderEnum) _spe = value ViewState("SearchProvider") =
value End Set End Property Figure 6: The
source code for a few of the more interesting SearchBox properties. The ShowSearchOptions property is fairly standard,
including a few attributes to make the design time experience friendlier. ViewState
is used to ensure values are stored between page postbacks. The
SearchProviderEnum enumeration is used by the SearchProvider property to allow
the developer to select Google, MSN, or MSN s Web service. The control is essentially rendered as a TextBox, Button,
and two RadioButtons. These child controls are created and configured from
within the overridden CreateChildControls event, as shown in Figure 7. Private WithEvents _txt As TextBox Private WithEvents _radio1 As RadioButton Private WithEvents _radio2 As RadioButton Private WithEvents _btn As Button Protected Overrides Sub CreateChildControls() MyBase.CreateChildControls() 'create a container for
all the controls Dim pnl As New Panel() pnl.ToolTip = Me.ToolTip pnl.CssClass =
Me.CssClass pnl.BackColor =
Me.BackColor pnl.ForeColor =
Me.ForeColor pnl.SkinID = Me.SkinID 'create the textbox
& add it to the container _txt = New TextBox _txt.Text = Me.Text _txt.ID =
"text" pnl.Controls.Add(_txt) 'create the button _btn = New Button _btn.Text =
Me.ButtonText _btn.PostBackUrl =
Me.PostBackURL _btn.ID =
"button" pnl.DefaultButton =
_btn.ClientID If Me.ButtonBelow =
False Then pnl.Controls.Add(_btn) pnl.Controls.Add(New
LiteralControl(" 'create the search
site/web radio buttons If Me.ShowSearchOptions
Then _radio1 = New
RadioButton _radio1.Text =
Me.SearchSiteText _radio1.GroupName =
"Search" _radio1.Checked =
Me.SearchSiteOnly _radio1.Style.Add(HtmlTextWriterStyle.FontSize, _ "x-small") _radio1.ID =
"SearchSite" pnl.Controls.Add(_radio1) _radio2 = New
RadioButton _radio2.Text =
Me.SearchTheWebText _radio2.GroupName = "Search" _radio2.Checked =
Not Me.SearchSiteOnly _radio2.Style.Add(HtmlTextWriterStyle.FontSize, _ "x-small") _radio2.ID =
"SearchWeb" pnl.Controls.Add(_radio2) pnl.Controls.Add(New
LiteralControl(" End If If Me.ButtonBelow Then
pnl.Controls.Add(_btn) Controls.Add(pnl) End Sub Figure 7: The
CreateChildControls method contains the code for instantiating and configuring
all the child controls. A panel control contains all the child controls so they ll
stay together in the same area of the Web form, and a few of the base control
properties are piped through to this panel. Next, the TextBox and Button are
instantiated. The Button is configured to be the panel s default button, which
is a new feature of ASP.NET 2.0. If the Button is configured to be beside the
TextBox, then it is immediately rendered; otherwise, the rendering is delayed
until the end of this subroutine. The RadioButtons are then instantiated and
configured if the ShowSearchOptions property is set to True. Finally, all the
controls are added to the containing panel control. Figure 8 shows the Search function, which (intuitively)
contains the meat of the logic for performing the simple search. It starts by
accepting a search string; otherwise, it uses the search string that was
previously supplied to the Text property. If the control was configured to use
the MSN Web Search Service, then control is handed off to another function
(listed in Figure 9) and an event is raised with the resulting DataTable. Otherwise,
the URL and QueryString are concatenated together and the user is redirected to
that address. Public Sub Search(Optional ByVal SearchText As String =
"") If SearchText.Trim.Length
> 0 Then Me.Text = SearchText If Me.Text.Trim.Length >
0 Then If Me.SearchProvider =
_ SearchProviderEnum.MSNWebService Then Dim dt As DataTable dt =
GetMSNWebSearchWebServiceResults() RaiseEvent
SearchResultsReady(dt) Else Dim sb As New
StringBuilder() If Me.SearchProvider
= SearchProviderEnum.MSN Then sb.Append("http://search.msn.com/results.aspx?q=") Else sb.Append("http://www.google.com/search?hl=en&q=") End If sb.Append(Context.Server.UrlEncode(_txt.Text)) If Me.SearchSiteOnly
AndAlso _ Me.SearchSite.Trim.Length > 0 Then sb.Append(Context.Server.UrlEncode(" site:")) sb.Append(Context.Server.UrlEncode(Me.SearchSite)) End If Context.Response.Redirect(sb.ToString) End If End If End Sub Figure 8: The
Search method contains most of the logic for performing searches by assembling
the correct URL and QueryString and redirecting the user to it. 'Queries the MSN search web service and returns a datatable 'containing the results. 'For more info on the MSN search web service, start here: 'http://msdn.microsoft.com/msn/gettingstarted/searchstart/ Protected Function GetMSNWebSearchWebServiceResults() _ As DataTable 'initialize variables Dim s As New MSNSearchService Dim searchRequest As New
SearchRequest Dim arraySize As Integer
= 1 Dim sr(arraySize) As
SourceRequest sr(0) = New SourceRequest sr(0).Source =
[SourceType].Web sr(0).ResultFields =
ResultFieldMask.Title _ Or ResultFieldMask.Url sr(0).Count = 20 'assemble the search
string Dim SearchText As String
= Me.Text & " " If Me.SearchSiteOnly _ AndAlso
Me.SearchSite.Trim.Length > 0 Then SearchText += "
site:" SearchText +=
Me.SearchSite End If 'call the msn search web
service searchRequest.Query =
SearchText searchRequest.Requests =
sr searchRequest.AppID =
Me.MSNApplicationID searchRequest.CultureInfo
= "en-US" Dim searchResponse As
SearchResponse searchResponse =
s.Search(searchRequest) 'fill a DataTable with
the results Dim dt As New DataTable Dim dc As New
DataColumn("Title") dt.Columns.Add(dc) dc = New
DataColumn("Url") dt.Columns.Add(dc) Dim sourceResponse As
SourceResponse For Each sourceResponse
In searchResponse.Responses Dim sourceResults As
Result() = sourceResponse.Results Dim sourceResult As
Result For Each sourceResult
In sourceResults Dim dr As DataRow =
dt.NewRow dr(0) =
sourceResult.Title dr(1) = sourceResult.Url dt.Rows.Add(dr) Next Next Return dt 'return the
DataTable End Function Figure 9: This
function calls the MSN Search Web Service, transforms the results into a
DataTable, and returns the DataTable. After adding a Web reference to the MSN Search Web Service
(located at http://soap.search.msn.com/webservices.asmx?wsdl)
the code in Figure 9 should be able to successfully call the MSN Search Web
Service. The MSN Search Web Service is very rich in functionality, providing a
wide array of capabilities that are beyond the scope of this article. To learn
more about the MSN Search Web Service, download the MSN Search SDK, which
includes documentation and several well-commented sample applications. I think you ll find the SearchBox to be a valuable
addition to your Visual Studio toolbox. No longer will you need to write custom
code to provide basic searching functionality for your Web site. This
functionality should work out of the box for most public Web sites, but I can
think of several nice enhancements for a future version of the control. For
example, you might add support for other search engines, or you might choose to
add a function to call Google s search Web service. Another option is to take
advantage of MSN s desktop search functionality, which may be useful for Web
sites that are not publicly available on the Internet (and therefore, are
unreachable by standard Web-based search engines). Google has certainly proved
that searching doesn t have to be boring. The possibilities are endless, so let
your mind wander and see what you come up with. The full source code
for the SearchBox control is available for download. Steve C. Orr is an
MCSD and a Microsoft MVP in ASP.NET. He s been developing software solutions
for leading companies in the Seattle
area for more than a decade. When he s not busy designing software systems or
writing about them, he can often be found loitering at local user groups and
habitually lurking in the ASP.NET newsgroup. Find out more about him at http://steveorr.net/
or e-mail him at mailto:[email protected].
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