Insert Checkboxes, Text Input, or Images

The merge engine takes a document as input, looks for MERGEFIELD fields in it, and replaces them with the data obtained from the data source. Typically, plain text and HTML are inserted, but Aspose.Words users can also generate a document that handles more unusual scenarios for Mail Merge fields.

Powerful Aspose.Words functionality allows you to extend the Mail Merge process:

• insert checkboxes and text input form fields into the document during a mail merge
• insert images from any custom storage (files, BLOB fields, etc.)

Insert Checkboxes and Text Input during Mail Merge

Sometimes it is necessary to perform a Mail Merge operation so that not text is substituted in the merge field, but a checkbox or text input field. Even though this is not the most common scenario, it is very handy for some tasks.

The following screenshot of a Word document shows a template with merge fields:

This screenshot of the Word document below shows the already generated document:

Note that some fields were replaced with plain text, some fields were replaced with checkbox form fields, and the Subject field was replaced with a text input field.

The following code example shows how to insert checkboxes and input text fields into a document during a mail merge:

// For complete examples and data files, please go to https://github.com/aspose-words/Aspose.Words-for-.NET.git.
Document doc = new Document(MyDir + "Mail merge destinations - Fax.docx");

// Setup mail merge event handler to do the custom work.
doc.MailMerge.FieldMergingCallback = new HandleMergeField();
// Trim trailing and leading whitespaces mail merge values.
doc.MailMerge.TrimWhitespaces = false;

string[] fieldNames = {
    "RecipientName", "SenderName", "FaxNumber", "PhoneNumber",
    "Subject", "Body", "Urgent", "ForReview", "PleaseComment"
};

object[] fieldValues = {
    "Josh", "Jenny", "123456789", "", "Hello",
    "<b>HTML Body Test message 1</b>", true, false, true
};

doc.MailMerge.Execute(fieldNames, fieldValues);

doc.Save(ArtifactsDir + "WorkingWithFields.MailMergeFormFields.docx");

// For complete examples and data files, please go to https://github.com/aspose-words/Aspose.Words-for-.NET.git.
private class HandleMergeField : IFieldMergingCallback
{
    /// <summary>
    /// This handler is called for every mail merge field found in the document,
    /// for every record found in the data source.
    /// </summary>
    void IFieldMergingCallback.FieldMerging(FieldMergingArgs e)
    {
        if (mBuilder == null)
            mBuilder = new DocumentBuilder(e.Document);

        // We decided that we want all boolean values to be output as check box form fields.
        if (e.FieldValue is bool)
        {
            // Move the "cursor" to the current merge field.
            mBuilder.MoveToMergeField(e.FieldName);

            string checkBoxName = $"{e.FieldName}{e.RecordIndex}";

            mBuilder.InsertCheckBox(checkBoxName, (bool) e.FieldValue, 0);

            return;
        }

        switch (e.FieldName)
        {
            case "Body":
                mBuilder.MoveToMergeField(e.FieldName);
                mBuilder.InsertHtml((string) e.FieldValue);
                break;
            case "Subject":
            {
                mBuilder.MoveToMergeField(e.FieldName);
                string textInputName = $"{e.FieldName}{e.RecordIndex}";
                mBuilder.InsertTextInput(textInputName, TextFormFieldType.Regular, "", (string) e.FieldValue, 0);
                break;
            }
        }
    }

    void IFieldMergingCallback.ImageFieldMerging(ImageFieldMergingArgs args)
    {
        args.ImageFileName = "Image.png";
        args.ImageWidth.Value = 200;
        args.ImageHeight = new MergeFieldImageDimension(200, MergeFieldImageDimensionUnit.Percent);
    }

    private DocumentBuilder mBuilder;
}

Insert Images during Mail Merge

When performing a Mail Merge operation, you can insert images from the database into the document using special image Mail Merge fields. The image Mail Merge field is a merge field named Image:MyFieldName.

Insert Images from a Database

During a mail merge, when an image Mail Merge field is encountered in a document, the FieldMergingCallback event is fired. You can respond to this event to return a filename, stream, or image object to the Mail Merge engine so it can be inserted into the document.

The following code example shows how to insert images stored in a database BLOB field into a report:

// For complete examples and data files, please go to https://github.com/aspose-words/Aspose.Words-for-.NET.git.
Document doc = new Document(MyDir + "Mail merge destination - Northwind employees.docx");

doc.MailMerge.FieldMergingCallback = new HandleMergeImageFieldFromBlob();

string connString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + DatabaseDir + "Northwind.accdb";
OleDbConnection conn = new OleDbConnection(connString);
conn.Open();

OleDbCommand cmd = new OleDbCommand("SELECT * FROM Employees", conn);
IDataReader dataReader = cmd.ExecuteReader();

doc.MailMerge.ExecuteWithRegions(dataReader, "Employees");

conn.Close();
            
doc.Save(ArtifactsDir + "WorkingWithFields.MailMergeImageFromBlob.docx");

// For complete examples and data files, please go to https://github.com/aspose-words/Aspose.Words-for-.NET.git.
public class HandleMergeImageFieldFromBlob : IFieldMergingCallback
{
    void IFieldMergingCallback.FieldMerging(FieldMergingArgs args)
    {
        // Do nothing.
    }

    /// <summary>
    /// This is called when mail merge engine encounters Image:XXX merge field in the document.
    /// You have a chance to return an Image object, file name, or a stream that contains the image.
    /// </summary>
    void IFieldMergingCallback.ImageFieldMerging(ImageFieldMergingArgs e)
    {
        // The field value is a byte array, just cast it and create a stream on it.
        MemoryStream imageStream = new MemoryStream((byte[]) e.FieldValue);
        // Now the mail merge engine will retrieve the image from the stream.
        e.ImageStream = imageStream;
    }
}

Set Image Properties during Mail Merge

While merging an image merge field, you may sometimes need to control various image properties, such as WrapType.

Currently, using ImageFieldMergingArgs you can only set image width or height properties, respectively. To overcome this issue, Aspose.Words provides the Shape property, which facilitates to get full control over the inserted image or any other shape.

The following code example shows how to set various image properties:

// For complete examples and data files, please go to https://github.com/aspose-words/Aspose.Words-for-.NET.git.
Document doc = new Document();
DocumentBuilder builder = new DocumentBuilder(doc);

builder.Writeln("{{#foreach example}}");
builder.Writeln("{{Image(126pt;126pt):stempel}}");
builder.Writeln("{{/foreach example}}");

doc.MailMerge.UseNonMergeFields = true;
doc.MailMerge.TrimWhitespaces = true;
doc.MailMerge.UseWholeParagraphAsRegion = false;
doc.MailMerge.CleanupOptions = MailMergeCleanupOptions.RemoveEmptyTableRows
        | MailMergeCleanupOptions.RemoveContainingFields
        | MailMergeCleanupOptions.RemoveUnusedRegions
        | MailMergeCleanupOptions.RemoveUnusedFields;

doc.MailMerge.FieldMergingCallback = new ImageFieldMergingHandler();
doc.MailMerge.ExecuteWithRegions(new DataSourceRoot());

doc.Save(ArtifactsDir + "WorkingWithFields.MailMergeImageField.docx");

// For complete examples and data files, please go to https://github.com/aspose-words/Aspose.Words-for-.NET.git.
private class ImageFieldMergingHandler : IFieldMergingCallback
{
    void IFieldMergingCallback.FieldMerging(FieldMergingArgs args)
    {
        //  Implementation is not required.
    }

    void IFieldMergingCallback.ImageFieldMerging(ImageFieldMergingArgs args)
    {
        Shape shape = new Shape(args.Document, ShapeType.Image)
        {
            Width = 126, Height = 126, WrapType = WrapType.Square
        };

        shape.ImageData.SetImage(MyDir + "Mail merge image.png");

        args.Shape = shape;
    }
}

// For complete examples and data files, please go to https://github.com/aspose-words/Aspose.Words-for-.NET.git.
public class DataSourceRoot : IMailMergeDataSourceRoot
{
    public IMailMergeDataSource GetDataSource(string s)
    {
        return new DataSource();
    }

    private class DataSource : IMailMergeDataSource
    {
        private bool next = true;

        string IMailMergeDataSource.TableName => TableName();

        private string TableName()
        {
            return "example";
        }

        public bool MoveNext()
        {
            bool result = next;
            next = false;
            return result;
        }

        public IMailMergeDataSource GetChildDataSource(string s)
        {
            return null;
        }

        public bool GetValue(string fieldName, out object fieldValue)
        {
            fieldValue = null;
            return false;
        }
    }
}