How to insert images into mail merge fields from different sources in a Word document?

Syncfusion® Essential® DocIO is a .NET Word library used to create, read, edit, and convert Word documents programmatically without Microsoft Word or interop dependencies. Using this library, you can insert images into mail merge fields from different sources in a Word document using C#.

In this article, we provide a code example to replace a merge field with images from different sources, such as a byte array, stream, URL and Base64 string. To achieve this, first, perform a mail merge, and then use the MergeImageFieldEventHandler to bind the image from the file system during the mail merge process.

Steps to insert images into mail merge fields from different sources in a Word document:

1. Create a new .NET Core console application project.
2. Install the Syncfusion.DocIO.Net.Core NuGet package as a reference to your project from NuGet.org.
   
   

3. Include the following namespaces in Program.cs file
   C#

using Syncfusion.DocIO.DLS;
using Syncfusion.DocIO; 

4. Use the following code example to insert images into mail merge fields from different sources in a Word document.
   C#

// Open the template Word document
using (FileStream inputFileStream = new FileStream(Path.GetFullPath("Data/Template.docx"), FileMode.Open, FileAccess.Read, FileShare.ReadWrite))
using (WordDocument document = new WordDocument(inputFileStream, FormatType.Automatic))
{
   // Attach the event handler for merging image fields
   document.MailMerge.MergeImageField += MergeField_ProductImage;
   // Define merge fields and corresponding image sources
   string[] fieldNames = { "ImageFromByteArray", "ImageFromStream", "ImageFromBase64", "ImageFromURL" };
   string[] fieldValues = { "Picture1.png", "Picture2.png", "base64.txt", "https://www.syncfusion.com/downloads/support/directtrac/general/AdventureCycle-1316159971.png" };
   // Perform the mail merge operation
   document.MailMerge.Execute(fieldNames, fieldValues);
   // Save the modified document to output
   using (FileStream outputFileStream = new FileStream(Path.GetFullPath("Output/Result.docx"), FileMode.Create, FileAccess.Write))
   {
       document.Save(outputFileStream, FormatType.Docx);
   }
}

5. Use the following code example to insert image into mail merge field position.
   C#

private static void MergeField_ProductImage(object sender, MergeImageFieldEventArgs args)
{
   string tempFilePath = null;
   FileStream imageStream = null;
   if (args.FieldName == "ImageFromStream")
   {
       // Load image from file as a stream
       string filePath = Path.Combine("Data", args.FieldValue.ToString());
       imageStream = new FileStream(filePath, FileMode.Open, FileAccess.Read);
   }
   else if(args.FieldName == "ImageFromByteArray")
   {
       byte[] imageBytes = File.ReadAllBytes(@"Data/" + args.FieldValue.ToString());
       tempFilePath = Path.GetTempFileName();
       File.WriteAllBytes(tempFilePath, imageBytes);
       imageStream = new FileStream(tempFilePath, FileMode.Open, FileAccess.Read);
   }
   else if (args.FieldName == "ImageFromBase64")
   {
       // Convert Base64 string to byte array and save as a temp file
       string base64String = File.ReadAllText(Path.Combine("Data", args.FieldValue.ToString()));
       byte[] imageBytes = Convert.FromBase64String(base64String);
       tempFilePath = Path.GetTempFileName();
       File.WriteAllBytes(tempFilePath, imageBytes);
       imageStream = new FileStream(tempFilePath, FileMode.Open, FileAccess.Read);
   }
   else if (args.FieldName == "ImageFromURL")
   {
       // Download image and save as a temp file
       WebClient client = new WebClient();
       byte[] urlImageBytes = client.DownloadData(args.FieldValue.ToString());
       tempFilePath = Path.GetTempFileName();
       File.WriteAllBytes(tempFilePath, urlImageBytes);
       imageStream = new FileStream(tempFilePath, FileMode.Open, FileAccess.Read);
   }
   if (imageStream != null)
   {
       args.ImageStream = imageStream;
       WPicture picture = args.Picture;
       picture.Height = 80;
       picture.Width = 150;
   }
} 

You can download a complete working sample to insert images into mail merge fields from different sources in a Word document from the GitHub.

Take a moment to peruse the documentation where you can find basic Word document processing options along with the features like mail merge, merge, split, and compare Word documents, find and replace text in the Word document, protect the Word documents, and most importantly, the PDF and Image conversions with code examples.

Conclusion

I hope you enjoyed learning about how to insert images into mail merge fields from different sources in a Word document in .NET Core Word document.

You can refer to our ASP.NET Core DocIO feature tour page to know about its other groundbreaking feature representations and documentation, and how to quickly get started for configuration specifications. You can also explore our ASP.NET Core DocIO example to understand how to create and manipulate data.

For current customers, you can check out our components from the License and Downloads page. If you are new to Syncfusion®, you can try our 30-day free trial to check out our other controls.

If you have any queries or require clarifications, please let us know in the comments section below. You can also contact us through our support forums, Direct-Trac, or feedback portal. We are always happy to assist you!