Exception when image column is null

Aspose.Words Product Family
1

Hi, Im having a problem during a mail merge with images in it. If the datatable column where the image data comes from is null then I get an exception:

DocumentGeneration.Tests.EmdaBrochureGeneratorFixture.GenerateSimplePropertyBrochure : System.ApplicationException : Could not insert image into document ‘PropertyImage’
----> System.InvalidCastException : Specified cast is not valid.

I am getting the cast error from this code:

protected virtual void HandleImageInsert(object sender, MergeImageFieldEventArgs e) {
try {
if (e.FieldValue != null) {
MemoryStream imageStream = new MemoryStream((byte[])e.FieldValue);
e.ImageStream = imageStream;
}
} catch (Exception ex) {
throw new ApplicationException(string.Format(“Could not insert image into document ‘{0}’”, e.FieldName), ex);
}
}

although the field has nothing in it my null check doesnt seem to be excluding it. Occasionally it does seem to work and when that happens I get an error saying the path is not valid. I assume this is because it expects a path to an image to be supplied in e.FieldValue.

If I have a dataset that has images in every row then it works fine… any help would be great!

2

Step through your code in the debugger carefully. Maybe your e.FieldValue is not null, but something else, I don’t know what. That’s why the check for null does not exclude it. e.FieldValue is also not a byte array in this case, that’s why it fails on the cast to (byte[]).

3

Hi,

I managed to fix this yesterday by doing the following:

try {
if (e.FieldValue != null && e.FieldValue.GetType() != typeof(DBNull)) {
MemoryStream imageStream = new MemoryStream((byte[])e.FieldValue);
Bitmap img = new Bitmap(imageStream);
e.Image = img;
} else {
e.Image = new System.Drawing.Bitmap(10, 10);
}
} catch (Exception ex) {
throw new ApplicationException(string.Format(“Could not insert image into document ‘{0}’”, e.FieldName), ex);
}

i was getting a dbnull type which is something i guess i should have known but i’ve not done all that much ado.net before…

it’s nice to see you use nunit and tdd too - i think its a really great technique. i’ve not used the debugger since i started using tdd about 6 months ago!