How to apply highlight color to fields 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 apply highlight color to fields in a Word document using C#.

Applying field shading programmatically is not possible because it is a viewer-level setting in Microsoft Word, not a file-level property. As a workaround, you can apply a highlight color to the field content. This provides a similar visual effect and is retained when the document is saved and reopened.

Steps to apply highlight color to fields 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 the Program.cs file.
   C#

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

4. Use the following code example to add fields in a Word document.
   C#

// Creates a new instance of WordDocument to work with.
using (WordDocument document = new WordDocument())
{
    // Add a new section to the Word document.
    IWSection section = document.AddSection();
    IWParagraph paragraph = section.AddParagraph();

    // Add text before the field (e.g., "Date Field - ").
    IWTextRange firstText = paragraph.AppendText("Date Field - ");
    // Adds a new Date field to the paragraph with the specified format.
    WField field = paragraph.AppendField("Date", FieldType.FieldDate) as WField;
    // Set the field code to display the date in "MMMM d, yyyy" format.
    field.FieldCode = @"DATE  \@" + "\"MMMM d, yyyy\"";
    // Reference the field as an entity.
    IEntity entity = field;
    // Apply shading to the field.
    ApplyShading(entity);

    // Add another paragraph for the "If" field.
    paragraph = section.AddParagraph();
    paragraph.AppendText("If Field - ");
    // Creates a new IF field.
    field = paragraph.AppendField("If", FieldType.FieldIf) as WIfField;
    // Specifies the field code for the IF statement with true and false branches.
    field.FieldCode = "IF \"True\" = \"True\" \"The given statement is Correct\" \"The given statement is Wrong\"";
    entity = field;
    // Apply shading to the field.
    ApplyShading(entity);

    // Updates the fields in the document.
    document.UpdateDocumentFields();

    // Create a file stream to save the document.
    using (FileStream outputFileStream = new FileStream(Path.GetFullPath(@"Output/Result.docx"), FileMode.Create, FileAccess.ReadWrite))
    {
        // Saves the Word document to the specified file stream in DOCX format.
        document.Save(outputFileStream, FormatType.Docx);
    }
}

5. Use the following code example to apply highlight color to the content of a field…
   C#

static void ApplyShading(IEntity entity)
{
    // Loop through the siblings of the current entity (field and its contents) until reaching the FieldEnd.
    while (entity.NextSibling != null)
    {
        // Check if the entity is a text range.
        if (entity is WTextRange)
        {
            // Set the highlight color to LightGray for the text range.
            (entity as WTextRange).CharacterFormat.HighlightColor = Color.LightGray;
        }
        // Check if the entity is a field mark and is of FieldEnd type.
        else if ((entity is WFieldMark) && (entity as WFieldMark).Type == FieldMarkType.FieldEnd)
        {
            // Break out of the loop once the end of the field is reached.
            break;
        }
        // Move to the next sibling entity (next part of the field).
        entity = entity.NextSibling;
    }
}

You can download a complete working sample to apply highlight color to fields in a Word document from GitHub.

Take a moment to peruse the documentation where you can find basic Word document processing options along with 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 apply shading to fields in a Word document in a .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 with 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!