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Consuming the Yahoo! Local Search Service in a Visual Basic WinForms Application

By , 18 Jan 2008
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Introduction

Yahoo’s Local Search Service is provided free of charge to developers through the Yahoo! Developer’s Network. This article will demonstrate one approach that may be used to consume this service to return a list of business locations through the use of a zip code based search for a business name or product.

The service returns the following information:

  • Title (the name of the business)
  • Street Address
  • City
  • State
  • Phone Number
  • Latitude and Longitude
  • The distance from the center of the zip code supplied by the user
  • URLs for maps and details about the business
  • URL of the business web site (if available)

This article will demonstrate the basics of submitting Local Search Service request, displaying the results, and accessing the available links returned in the search results. Naturally there are a number of ways in which we could present the search results and this demonstration application only illustrates one such possibility. For more information regarding the program, refer directly to the Yahoo Developer Network website located here.

The service may be accessed up to 50,000 times a day; participation in the program is free and is contingent upon signing up for the Yahoo! Developers Network and obtaining an application ID from Yahoo!

When visiting the Yahoo! site, take a look at the different programs available and take a look at some of the many services made available through Yahoo.

Figure 1: The demonstration application running.

Figure 2: Providing Context Menu Access to the Map, Business, and Business Details URLs.

Figure 3: Displaying the Map to the Business.

Figure 4: Displaying the Business Website.

Figure 5: Displaying the Yahoo! Business Details.

Getting Started

In order to get started, unzip the included project and open the solution in the Visual Studio 2005 environment. In the solution explorer, you should note these files:

Figure 6: Solution Explorer.

The Main Form (frmSearch.vb)

The main form (frmSearch.vb) is the only form contained in the application; all of the application specific code required to access the service, return the results of an local search, and to display those results in a datagridview control or as a web page are included in this class.

The code is pretty simple, if you'd care to open the code view up in the IDE, you will see that the code file begins as follows:

''' <span class="code-SummaryComment"><summary></span>
''' Consume the Yahoo! Local Search Service
''' in a Visual Basic WinForms application
''' <span class="code-SummaryComment"></summary></span>
''' <span class="code-SummaryComment"><remarks></remarks></span>
Public Class frmSearch

    ''' <span class="code-SummaryComment"><summary></span>
    ''' Default Constructor
    ''' <span class="code-SummaryComment"></summary></span>
    ''' <span class="code-SummaryComment"><remarks></remarks></span>
    Public Sub New()

        ' This call is required by the Windows Form Designer.
        InitializeComponent()

        ' the user's zip code likely won't change so
        ' set the zip code to user last entered zip code
        Me.txtZipCode.Text = My.MySettings.Default.MyZipCode

    End Sub

Note that in the constructor, the zip code textbox control is populated from a user setting stored in the application. Each time the user changes the zip code, the last entered zip code is stored in this setting and the next time the application is used, the last zip code is restored into the textbox.

The next section of code is the button click event handler for the search button. When this button is clicked, the method will verify that the user has entered a search term and zip code. It will store the current zip code into the user setting (in case the user changed it) and then it will call a separate method called LocalSearch which accepts two arguments: the title of the business or product name, and the zip code.

''' <span class="code-SummaryComment"><summary></span>
''' Initiate a Yahoo! Local Search Service
''' request based upon the user supplied
''' product/business name and zip code
''' <span class="code-SummaryComment"></summary></span>
''' <span class="code-SummaryComment"><param name="sender"></param></span>
''' <span class="code-SummaryComment"><param name="e"></param></span>
''' <span class="code-SummaryComment"><remarks></remarks></span>
Private Sub btnSearch_Click(ByVal sender As System.Object, _
    ByVal e As System.EventArgs) Handles btnSearch.Click

    ' validate that search terms were entered
    ' by making sure that the business/product
    ' and the zip code textboxes contain something
        If txtBusinessOrProduct.Text <> String.Empty Or _
            txtZipCode.Text <> String.Empty Then

            ' save last entered zip code in user setting
            ' so that the next time the application is used
            ' we can retrieve this zip code and reuse it
            My.MySettings.Default.MyZipCode = txtZipCode.Text
            My.MySettings.Default.Save()
    
            ' call the search with the product and zip code arguments
            ' this function will populate the datagrid with the
            ' values returned from the product search
            LocalSearch(txtBusinessOrProduct.Text, txtZipCode.Text)
    
        Else
            ' tell the user that the search requested is invalid
            ' if they failed to fill in both the product/business and
            ' zip code textboxes
            MessageBox.Show("You must supply both a zip code and
            product/business name.", "Search Invalid")
        End If

    End Sub

The next section of the code is used to execute the local search. The first part of the code stores the business or product name into a string variable and then trims the zip code string to prevent a zip+4 entry; the textbox that accepts the zip code is limited to only five characters in length, so this is not really necessary. An HTTP Web request is then formatted to execute the search against the Yahoo! Local Search service; this request uses the supplied business or product name along with the supplied zip code to limit the number of results returned. The service limits the results to a maximum of 20 entries.

The derived response stream is used to populate a dataset; the dataset’s second table is then bound to the datagridview. The second table contains the results of the search; a total of three tables are returned by the service and contain information regarding the business rating and the total number of hits returned by the search.

''' <span class="code-SummaryComment"><summary></span>
''' Conduct a search for products or business names
''' within a specified zip code using the Yahoo!
''' Local Search Service
''' <span class="code-SummaryComment"></summary></span>
''' <span class="code-SummaryComment"><remarks></remarks></span>
Private Sub LocalSearch(ByVal business As String, _
    ByVal zipCode As String)

    Try

        ' business or product name
        Dim biz As String = business

        ' take only the zip code (not zip + 4)
        Dim zip As String = zipCode.Substring(0, 5)

        ' format the Web request using
        ' the zip code and business/product name
        ' passed in as arguments
        ' NOTE:  The appid should be replaced with the
        ' appid supplied by Yahoo! when the developer
        ' signs up with the free developer network
        Dim request As System.Net.HttpWebRequest _
            = System.Net.WebRequest.Create( _
              "http://local.yahooapis.com/LocalSearchService/V2/_
              localSearch?appid=YahooDemo&query=" + biz + "&zip=" + zip + "&results=20")

        ' get HTTP Web response for the Web request
        Using response As System.Net.HttpWebResponse = _
            request.GetResponse()

            ' populate the dataset using the
            ' response stream (in XML)
            Dim dsSearch As DataSet = New DataSet()
            dsSearch.ReadXml(response.GetResponseStream())

            ' populate the datagridview control using the
            ' second table (which contains the actual search
            ' results - in all three tables are returned
            dataGridView1.DataSource = dsSearch.Tables(1)
            dataGridView1.Refresh()

        End Using

    Catch ex As Exception

        ' describe any encountered error if the
        ' local search should fail for any reason
        MessageBox.Show(ex.Message, "Error")

    End Try

End Sub

The final three methods contained in the class are used to open up the business, map, and details links provided in the results obtained for any specific business.

''' <span class="code-SummaryComment"><summary></span>
''' Open the Map URL for the currently selected row
''' contained in the results datagridview control
''' <span class="code-SummaryComment"></summary></span>
''' <span class="code-SummaryComment"><param name="sender"></param></span>
''' <span class="code-SummaryComment"><param name="e"></param></span>
''' <span class="code-SummaryComment"><remarks></remarks></span>
Private Sub mapURLToolStripMenuItem_Click(ByVal sender As System.Object, _
    ByVal e As System.EventArgs) Handles mapURLToolStripMenuItem.Click

    Try
        ' get the cell value for the map URL
        Dim url As String
        url = dataGridView1.SelectedRows(0).Cells(10).Value.ToString()
    
        ' open the URL into a browser window
        System.Diagnostics.Process.Start(url)

    Catch
        ' display an error message to the user
        ' if the URL does not exist or was invalid
        MessageBox.Show("Invalid or Missing URL", "Map URL Error")
    End Try

End Sub

''' <span class="code-SummaryComment"><summary></span>
''' Open the Business URL for the currently selected row
''' contained in the results datagridview control
''' <span class="code-SummaryComment"></summary></span>
''' <span class="code-SummaryComment"><param name="sender"></param></span>
''' <span class="code-SummaryComment"><param name="e"></param></span>
''' <span class="code-SummaryComment"><remarks></remarks></span>
Private Sub businessURLToolStripMenuItem_Click(ByVal sender As _
    System.Object, ByVal e As System.EventArgs) Handles _
    businessURLToolStripMenuItem.Click

    Try
        ' get the cell value for the map URL
        Dim url As String
        url = dataGridView1.SelectedRows(0).Cells(11).Value.ToString()

        ' open the URL into a browser window
        System.Diagnostics.Process.Start(url)

    Catch
        ' display an error message to the user
        ' if the URL does not exist or was invalid
        MessageBox.Show("Invalid or Missing URL", "Business URL Error")
    End Try

End Sub

''' <span class="code-SummaryComment"><summary></span>
''' Open the Business Details URL for the currently selected row
''' contained in the results datagridview control
''' <span class="code-SummaryComment"></summary></span>
''' <span class="code-SummaryComment"><param name="sender"></param></span>
''' <span class="code-SummaryComment"><param name="e"></param></span>
''' <span class="code-SummaryComment"><remarks></remarks></span>
Private Sub detailsToolStripMenuItem_Click(ByVal sender As System.Object, _
    ByVal e As System.EventArgs) Handles detailsToolStripMenuItem.Click

    Try
        ' get the cell value for the map URL
        Dim url As String
        url = dataGridView1.SelectedRows(0).Cells(8).Value.ToString()
    
        ' open the URL into a browser window
        System.Diagnostics.Process.Start(url)

    Catch
        ' display an error message to the user
        ' if the URL does not exist or was invalid
        MessageBox.Show("Invalid or Missing URL", "Business Details URL
        Error")
    End Try

End Sub

Summary

This application was provided as an example of how one might take advantage of the Yahoo! Local Search service in a Visual Basic WinForms application. The service returns information about the business and returns a collection of links that may be used to display a map of the business, the business Web site, and Yahoo! collected information pertaining to the business.

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

About the Author

salysle
Software Developer (Senior)
United States United States
No Biography provided

Comments and Discussions

 
GeneralIncrease the Number of Results [modified] Pinmemberaaroncampf24-Jan-11 13:00 

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