Conversion error when trying to call an image if database value is NULL. RSS

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  morrisandy

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  46 Posts

  Conversion error when trying to call an image if database value is NULL.

  Feb 04, 2012 02:32 AM|LINK

  I am trying to load an image onto a web form depending on the image's URL path inside a database. I can get this to work, however I am trying to display a dummy image incase the record in the database has no image and the column is NULL.

  Below is the code that I imagined would work but I receive an error:

  Conversion from type 'DBNull' to type 'String' is not valid.

  
  Please can anyone steer me in the right direction or what best practice I should take please? Thanks

  '// Load Item Image in imgMenuItem Image Control //
  If (Not IsDBNull(Rdr("img_url"))) Then
   imgMenuItem.ImageUrl = Rdr("img_url")
   imgMenuItem.DataBind()
  Else
   imgMenuItem.ImageUrl = ("Admin/Images/ItemImageHolder.jpg")
  End If

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  Gayomard Meh...

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  241 Posts

  Re: Conversion error when trying to call an image if database value is NULL.

  Feb 04, 2012 05:14 AM|LINK

  Why dont you handle this scenario on the back end ... you could use the SQL Server ISNULL() function to do this...

  Please mark this as the answer if it was useful.
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  Qi Wu - MSFT

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  Re: Conversion error when trying to call an image if database value is NULL.

  Feb 06, 2012 07:30 AM|LINK

  Hi,

  The return type of the Rdr(“img_url”) may be the string. You don’t need to use the IsDBNull() method. You may try the below code.

  If( Not String.IsNullOrEmpty(Rdr("img_url"))) Then
              imgMenuItem.ImageUrl = Rdr("img_url")
              imgMenuItem.DataBind()
          Else
              imgMenuItem.ImageUrl = ("Admin/Images/ItemImageHolder.jpg")
          End If

  Please mark the replies as answers if they help or unmark if not.
  If you have any feedback about my replies, please contact msdnmg@microsoft.com
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  MetalAsp.Net

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  Re: Conversion error when trying to call an image if database value is NULL.

  Feb 06, 2012 07:41 AM|LINK

  Try like this: If (Not Convert.IsDBNull(Rdr("img_url")))

  Otherwise, put a breakpoint on the line and check what the value of Rdr("img_url") is, to get an idea on how to handle it.

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  morrisandy

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  30 Points

  46 Posts

  Re: Conversion error when trying to call an image if database value is NULL.

  Feb 06, 2012 03:06 PM|LINK

  Thanks for all your responces, however I noticed after I removed the () around the image url (/Admin/Images/ItemImageHolder.jpg) seemed to do the trick just fine. Along with removing the imgMenuItem.DataBind() Unsure why that would have cause a conversion error but still the following seemed to do the trick:

  If (Not IsDBNull(Rdr("img_url"))) Then
   imgMenuItem.ImageUrl = Rdr("img_url")
  Else
   imgMenuItem.ImageUrl = "/Admin/Images/ItemImageHolder.jpg"
  End If

  Anybody know why this may of happened?

  • Marked as answer by morrisandy on Feb 19, 2012 04:45 PM
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  tanatrajan

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  Re: Conversion error when trying to call an image if database value is NULL.

  Feb 06, 2012 04:07 PM|LINK

  This is a c# conditional if statement, please replace with VB system if you need
  
  imgMenuItem.ImageUrl = (Rdr["img_url"] == DBNull.Value) ? "Admin/Images/ItemImageHolder.jpg" : Rdr["img_url"].ToString();

  Please mark my reply as answer if it helped.