Optimize LINQ Query for use with jQuery Autocomplete

Posted by rockinthesixstring on Stack Overflow See other posts from Stack Overflow or by rockinthesixstring
Published on 2010-05-20T02:40:21Z Indexed on 2010/05/20 2:50 UTC
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I'm working on building an HTTPHandler that will serve up plain text for use with jQuery Autocomplete. I have it working now except for when I insert the first bit of text it does not take me to the right portion of the alphabet.

Example: If I enter Ne

my drop down returns

Nlabama
Arkansas

Notice the "N" from Ne and the "labama" from "Alabama"

As I type the third character New, then the jQuery returns the "N" section of the results.

My current code looks like this

Public Sub ProcessRequest(ByVal context As System.Web.HttpContext) Implements System.Web.IHttpHandler.ProcessRequest
    ' the page contenttype is plain text'
    HttpContext.Current.Response.ContentType = "text/plain"

    ' store the querystring as a variable'
    Dim qs As Nullable(Of Integer) = Integer.TryParse(HttpContext.Current.Request.QueryString("ID"), Nothing)

    ' use the RegionsDataContext'
    Using RegionDC As New DAL.RegionsDataContext

        'create a (q)uery variable'
        Dim q As Object

        ' if the querystring PID is not blank'
        ' then we want to return results based on  the PID'
        If Not qs Is Nothing Then
            ' that fit within the Parent ID'
            q = (From r In RegionDC.bt_Regions _
                    Where r.PID = qs _
                   Select r.Region).ToArray

            ' now we loop through the array'
            ' and write out the ressults'
            For Each item In q
                HttpContext.Current.Response.Write(item & vbCrLf)
            Next

        End If


    End Using
End Sub

So where I'm at now is the fact that I stumbled on the "Part" portion of the Autocomplete method whereby I should only return information that is contained within the Part.

My question is, how would I implement this concept into my HTTPHandler without doing a fresh SQLQuery on every character change? IE: I do the SQL Query on the QueryString("ID"), and then on every subsequent load of the same ID, we just filter down the "Part".

http://www.example.com/ReturnRegions.axd?ID=[someID]&Part=[string]

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