Hi
Thanks for your inquiry. You can easily achieve this using MergeField event handler. Please see the following link for more information:
https://reference.aspose.com/words/net/aspose.words.mailmerging/ifieldmergingcallback/
Also here a simple code, which you can use:
// Open template.
Document doc = new Document(@"Test001\in.doc");
// Add MergeField event handler.
doc.MailMerge.MergeField += new MergeFieldEventHandler(MailMergeTrimValues);
// Execute mail merge.
doc.MailMerge.Execute(new string[]
{
"field1",
"field2",
"field3"
}, new object[]
{
" 123",
"123 ",
" 123 "
});
// Save output document.
doc.Save(@"Test001\out.doc");
void MailMergeTrimValues(object sender, MergeFieldEventArgs e)
{
// Trim the value before insertign it into the document.
e.Text = e.FieldValue.ToString().Trim();
}
Hope this helps.
Best regards.