MailMergeMappedDataFields Property

Returns a collection that represents mapped data fields for the mail merge operation.

Namespace:  Aspose.Words.MailMerging
Assembly:  Aspose.Words (in Aspose.Words.dll) Version: 20.9.0


public MappedDataFieldCollection MappedDataFields { get; }

Property Value

Type: MappedDataFieldCollection


Mapped data fields allow to automatically map between names of fields in your data source and names of mail merge fields in the document.


Shows how to map data columns and MERGEFIELDs with different names so the data is transferred between them during a mail merge.
public void MappedDataFieldCollection()
    // Create a document and table that we will merge
    Document doc = CreateSourceDocMappedDataFields();
    DataTable dataTable = CreateSourceTableMappedDataFields();

    // We have a column "Column2" in the data table that does not have a respective MERGEFIELD in the document
    // Also, we have a MERGEFIELD named "Column3" that does not exist as a column in the data source
    // If data from "Column2" is suitable for the "Column3" MERGEFIELD,
    // we can map that column name to the MERGEFIELD in the "MappedDataFields" key/value pair
    MappedDataFieldCollection mappedDataFields = doc.MailMerge.MappedDataFields;

    // A data source column name is linked to a MERGEFIELD name by adding an element like this
    mappedDataFields.Add("MergeFieldName", "DataSourceColumnName");

    // So, values from "Column2" will now go into MERGEFIELDs named "Column3" as well as "Column2", if there are any
    mappedDataFields.Add("Column3", "Column2");

    // The MERGEFIELD name is the "key" to the respective data source column name "value"
    Assert.AreEqual("DataSourceColumnName", mappedDataFields["MergeFieldName"]);

    // Now if we run this mail merge, the "Column3" MERGEFIELDs will take data from "Column2" of the table

    // We can count and iterate over the mapped columns/fields
    Assert.AreEqual(2, mappedDataFields.Count);

    using (IEnumerator<KeyValuePair<string, string>> enumerator = mappedDataFields.GetEnumerator())
        while (enumerator.MoveNext())
                $"Column named {enumerator.Current.Value} is mapped to MERGEFIELDs named {enumerator.Current.Key}");

    // We can also remove some or all of the elements

    Assert.AreEqual(0, mappedDataFields.Count);

    // Removing the mapped key/value pairs has no effect on the document because the merge was already done with them in place
    doc.Save(ArtifactsDir + "MailMerge.MappedDataFieldCollection.docx");

/// <summary>
/// Create a document with 2 MERGEFIELDs, one of which does not have a corresponding column in the data table.
/// </summary>
private static Document CreateSourceDocMappedDataFields()
    Document doc = new Document();
    DocumentBuilder builder = new DocumentBuilder(doc);

    // Insert two MERGEFIELDs that will accept data from that table
    builder.InsertField(" MERGEFIELD Column1");
    builder.Write(", ");
    builder.InsertField(" MERGEFIELD Column3");

    return doc;

/// <summary>
/// Create a data table with 2 columns, one of which does not have a corresponding MERGEFIELD in our source document.
/// </summary>
private static DataTable CreateSourceTableMappedDataFields()
    // Create a data table that will be used in a mail merge
    DataTable dataTable = new DataTable("MyTable");
    dataTable.Rows.Add(new object[] { "Value1", "Value2" });

    return dataTable;

See Also