Question

Basically in my in my aspx page I have a gridview which displays the value from my database as an image. So if a value in my database table is 5, it will be displayed as 5 images in the gridview. ie.(star.jpg star.jpg star.jpg star.jpg star.jpg)

The code:

Protected Function getrating(ByVal rate As Integer)
        Dim getrating As String
        getrating = ""
        For i = 1 To rate
            getrating = getrating + "<img src=""Images/star.jpg"" alt=""*"">"
        Next
        Return getrating
    End Function

It’s been working fine so far for whole numbers, but now I’m adding averages into my database, so any value with a decimal point(like 4.6) gives me the error

"Conversion from type 'DBNull' to type 'Integer' is not valid."

How would I go about in adding images when the value has a decimal point?

Since the field in my database has the range set to numbers 1 to 5, I like it to display another image if the value has a decimal point. ie. “3.5” would display in the gridview star.jpg, star.jpg, star.jpg, halfstar.jpg. If that made any sense lol.

Anyone have an idea on how to do doing this?

Answer 1

Judging by your error, it’s probable that you’re not even accepting decimal values and inserting the NULL value when they occur. Fix that first, make sure the result isn’t DBNull, then you can make the changes to a decimal type like Double:

Protected Function GetRating(ByVal rating As Double) As String
    Dim result As New System.Text.StringBuilder()

    While rating >= 1.0#
        result.Append("<img src=""Images/star.jpg"" alt=""*"">")
        rating -= 1.0#
    End While

    If rating > 0.0# Then _
        result.Append("<img src=""Images/halfstar.jpg"" alt=""1/2"">")

    Return result.ToString()
End Function

I also took the liberty of using a StringBuilder instead of concatenating strings with +.