# Mail Merge with MS Word Documents in C# - An Ultimate Guide > The MailMerge class provides a very effective way to merge data into MS Word compatible templates. This ultimate guide gives an overview of all important features and functionalities of the mail merge process. - **Author:** Bjoern Meyer - **Published:** 2022-05-25 - **Modified:** 2025-11-16 - **Description:** The MailMerge class provides a very effective way to merge data into MS Word compatible templates. This ultimate guide gives an overview of all important features and functionalities of the mail merge process. - **9 min read** (1657 words) - **Tags:** - ASP.NET - Mail Merge - Windows Forms - WPF - **Web URL:** https://www.textcontrol.com/blog/2022/05/25/mail-merge-with-ms-word-documents-in-csharp-an-ultimate-guide/ - **LLMs URL:** https://www.textcontrol.com/blog/2022/05/25/mail-merge-with-ms-word-documents-in-csharp-an-ultimate-guide/llms.txt - **LLMs-Full URL:** https://www.textcontrol.com/blog/2022/05/25/mail-merge-with-ms-word-documents-in-csharp-an-ultimate-guide/llms-full.txt --- The MailMerge class provides a very effective way to merge data into merge field placeholders, repeating blocks, form fields, barcodes, images and chart objects. This engine handles the dynamic generation of documents based on document templates. Typically, the *MailMerge* API is used to automate the document generation to create letters, invoices, quotations and other dynamic documents. This article provides an overview of typical mail merge functionality and the available features and settings. ### What is Mail Merge? Mail Merge describes the process to create documents based on templates that contain static content and variable elements that are merged from various data sources. - **The template** A template can be any document type that is supported by TX Text Control including DOC, DOCX, RTF and the internal TX Text Control format (TX). The template can contain static text and dynamic merge fields, image placeholders, repeating blocks and other merge elements. ![Creating documents with TX Text Control](https://s1-www.textcontrol.com/assets/dist/blog/2022/05/25/a/assets/merge1.webp "Creating documents with TX Text Control") - **The data source** *MailMerge* provides various methods to merge data into templates. *MailMerge* interprets all public properties of an object as table columns and child tables. The object type is analyzed using .NET reflection and used as the basis of the table structure. Nested object types are used for merge blocks and prefixed merge fields. Supported data types are: - DataSet - DataTable - JSON - XML - IEnumerable objects ### Mail Merge Process Using TX Text Control, merging data into MS Word compatible templates can be effortlessly done in 3 simple steps. - Loading a template - Merging with data - Exporting the document The MailMerge class merges the data from various data sources into documents. It can be connected to any Text Control (TXTextControl.ServerTextControl, TXTextControl.TextControl and TXTextControl.WPF.TextControl. The document that is loaded into the connected *Text Control* is automatically used as the mail merge template. The following code shows how to create a *Mailmerge* instance and how to connect it to a *ServerTextControl*: ``` using (MailMerge mailMerge = new MailMerge()) { mailMerge.TextComponent = textControl1; } ``` In the next code snippet an Office Open XML (DOCX) template is loaded into a new *ServerTextControl* instance that is then connected to *MailMerge*: ``` TXTextControl.LoadSettings ls = new TXTextControl.LoadSettings() { ApplicationFieldFormat = TXTextControl.ApplicationFieldFormat.MSWord }; using (TXTextControl.ServerTextControl serverTextControl = new TXTextControl.ServerTextControl()) { serverTextControl.Create(); serverTextControl.Load("template.docx", TXTextControl.StreamType.WordprocessingML, ls); using (MailMerge mailMerge = new MailMerge()) { mailMerge.TextComponent = serverTextControl; } } ``` The template can be any MS Word document with merge fields that can be added using the pre-designed *Reporting* ribbon tab of the TX Text Control visual editor or using MS Word. The sample template is shown in the next screenshot: ![Creating documents with TX Text Control](https://s1-www.textcontrol.com/assets/dist/blog/2022/05/25/a/assets/merge1.webp "Creating documents with TX Text Control") ### Merging with Data For simplicity, the following JSON string is used as the data source: ``` [ { "company_name": "Text Control, LLC", "address": { "street": "1111 Text Control Way", "zip": "28226", "city": "Charlotte", "country": "United States" } } ] ``` In the next code snippet, the MergeJsonData is used to merge the template with the given JSON data. ``` // enable MS Word merge fields TXTextControl.LoadSettings ls = new TXTextControl.LoadSettings() { ApplicationFieldFormat = TXTextControl.ApplicationFieldFormat.MSWord }; // load JSON data string jsonData = System.IO.File.ReadAllText("data.json"); // create a temporary ServerTextControl using (TXTextControl.ServerTextControl serverTextControl = new TXTextControl.ServerTextControl()) { serverTextControl.Create(); // load the template serverTextControl.Load("template.docx", TXTextControl.StreamType.WordprocessingML, ls); // create the mail merge engine using (MailMerge mailMerge = new MailMerge()) { // connect to ServerTextControl mailMerge.TextComponent = serverTextControl; // merge data into template mailMerge.MergeJsonData(jsonData); } } ``` The resulting document is shown in the screenshot: ![Creating documents with TX Text Control](https://s1-www.textcontrol.com/assets/dist/blog/2022/05/25/a/assets/merge2.webp "Creating documents with TX Text Control") ### Exporting the Document After a successful merge process, the resulting document is loaded into the connected *Text Control* instance and can be exported to any supported document format. The following code shows how the resulting document is getting exported as an Adobe PDF document. ``` TXTextControl.LoadSettings ls = new TXTextControl.LoadSettings() { ApplicationFieldFormat = TXTextControl.ApplicationFieldFormat.MSWord }; string jsonData = System.IO.File.ReadAllText("data.json"); using (TXTextControl.ServerTextControl serverTextControl = new TXTextControl.ServerTextControl()) { serverTextControl.Create(); serverTextControl.Load("template.docx", TXTextControl.StreamType.WordprocessingML, ls); using (MailMerge mailMerge = new MailMerge()) { mailMerge.TextComponent = serverTextControl; mailMerge.MergeJsonData(jsonData); } // export document as PDF serverTextControl.Save("results.pdf", TXTextControl.StreamType.AdobePDF); } ``` ### Data Structures This chapter explains the data structure based on a sample JSON object that contains hierarchical data and allows to show different mail merge features including access to data from child tables and nested, repeating merge blocks.: ``` [ { "company_name": "Text Control, LLC", "address": { "street": "1111 Text Control Way", "zip": "28226", "city": "Charlotte", "country": "United States" }, "contacts": [ { "name": "Tim Typer", "email": "tim@textcontrol.com" }, { "name": "Karl Keyboard", "email": "karl@textcontrol.com" }, { "name": "Petra Paragraph", "email": "petra@textcontrol.com" } ], "orders": [ { "id": 123, "articles": [ { "id": 1, "product": { "name": "Product A", "description": "Description of product A", "price": 200 }, "qty": 5, "discount": 0.2 }, { "id": 2, "product": { "name": "Product B", "description": "Description of product B", "price": 244 }, "qty": 50, "discount": 0.0 }, { "id": 3, "product": { "name": "Product C", "description": "Description of product C", "price": 677 }, "qty": 2, "discount": 0.5 } ] }, { "id": 321, "articles": [ { "id": 1, "product": { "name": "Product B", "description": "Description of product B", "price": 123 }, "qty": 12, "discount": 0.0 }, { "id": 2, "product": { "name": "Product D", "description": "Description of product D", "price": 556 }, "qty": 2, "discount": 0.7 }, { "id": 3, "product": { "name": "Product C", "description": "Description of product C", "price": 677 }, "qty": 20, "discount": 0.3 } ] } ] } ] ``` Internally, the hierarchical structure is converted into tables. The following diagram shows these tables including their child tables: ![Sample data](https://s1-www.textcontrol.com/assets/dist/blog/2022/05/25/a/assets/classes.webp "Sample data") ### The Sample Template The [sample template](https://s1-www.textcontrol.com/assets/dist/blog/2022/05/25/a/assets/sample.zip) that is used in this article is very simple and contains static data, simple merge fields and a nested, repeating block. The merge block will list all "orders" from the sample data: ![Sample template](https://s1-www.textcontrol.com/assets/dist/blog/2022/05/25/a/assets/template.webp "Sample template") First, we take a look at the address part of the template. For this part, 3 tables are used and accessed in different ways. ![Sample template](https://s1-www.textcontrol.com/assets/dist/blog/2022/05/25/a/assets/structure_header.webp "Sample template") ### Accessing Child Tables *company\_name* comes from the root table directly while the address is coming from a child table. These fields can be accessed using the "dot notation". For example, to access the street, the merge field name is *address.street*. The *contacts* part contains a merge block (highlighted in red below) to list all of the contacts. A merge block repeats all elements part of the block based on the data for this block. In this case, the block includes a soft break and the tab character, so that all contacts are listed at the same indent position: ![Sample template](https://s1-www.textcontrol.com/assets/dist/blog/2022/05/25/a/assets/block.webp "Sample template") The following animation shows the header section before and after the merge process: ![Sample template](https://s1-www.textcontrol.com/assets/dist/blog/2022/05/25/a/assets/header_animation.webp "Sample template") ### Repeating Blocks The detail section lists all orders and their articles. Therefore, two nested merge blocks are inserted. The outer block repeats the *orders* objects and the inner block lists all *articles*: ![Sample template](https://s1-www.textcontrol.com/assets/dist/blog/2022/05/25/a/assets/details.webp "Sample template") As can be seen in the following animation, the outer block is getting repeated 2 times based on the actual data in the given JSON. The inner table row is defined as the nested block *articles* and contains all line items: ![Sample template](https://s1-www.textcontrol.com/assets/dist/blog/2022/05/25/a/assets/details_animation.webp "Sample template") ### Mail Merge Article Collection Additionally, *MailMerge* provides various events and settings that can be used to implement complex reporting scenarios. The following list contains detailed articles about specific mail merge features and most typical applications. ### Field Mapping > **MailMerge: Field Mapping and Handling of Unmerged Fields** > > Text Control's MailMerge API maps merge fields in templates with columns in supported data sources. This article explains the structure and how to handle unmerged fields. > > [Read article ](https://www.textcontrol.com/blog/2022/05/04/mailmerge-field-mapping-and-handling-of-unmerged-fields/llms-full.txt) ### Conditional Table Rows > **MailMerge: Field Mapping and Handling of Unmerged Fields** > > The MailMerge class supports repeating merge blocks that are repeated based on the given data rows. Sub-blocks can be rendered conditionally based on value comparisons of the parent data table. This article shows how to add such a condition. > > [Read article ](https://www.textcontrol.com/blog/2022/02/17/mailmerge-rendering-conditional-table-rows/llms-full.txt) ### Form Fields > **Merging Form Fields using the MailMerge Class** > > Usually, the MailMerge class is used to merge data into document templates to replace merge fields. Since version 30.0, it is possible to merge data into form fields. > > [Read article ](https://www.textcontrol.com/blog/2022/02/21/merging-form-fields-using-the-mailmerge-class/llms-full.txt) ### Merging Charts > **Using MailMerge with Chart Objects and JSON Data** > > This article explains how to merge JSON data into chart objects using the MailMerge class. > > [Read article ](https://www.textcontrol.com/blog/2022/02/21/merging-form-fields-using-the-mailmerge-class/llms-full.txt) ### Conditional Formatting > **Implementing Conditional Table Cell Colors with MailMerge** > > The MailMerge class provides an extensible framework to inject custom logic to the merge process. This ASP.NET MVC sample shows how to implement conditional table cell colors using the online document editor and an ASP.NET backend. > > [Read article ](https://www.textcontrol.com/blog/2020/10/08/implementing-conditional-table-cell-colors-with-mailmerge/llms-full.txt) ### String Formatter > **Format Numeric String Values with MailMerge** > > Numeric format strings are used to format common numeric types. This article gives an overview of supported format strings and how to apply them to merge fields. > > [Read article ](https://www.textcontrol.com/blog/2020/10/22/format-numeric-string-values-with-mailmerge/llms-full.txt) ### Merge Blocks Sorting > **Adding Sorting and Filter Instructions to Existing MergeBlocks** > > Merge blocks can be filtered and sorted with linked instructions that help to shape the used data in each merge block. This article shows how to add sorting and filter instructions to existing merge blocks. > > [Read article ](https://www.textcontrol.com/blog/2021/07/16/adding-sorting-and-filter-instructions-to-existing-mergeblocks/llms-full.txt) --- ## About Bjoern Meyer As CEO, Bjoern is the visionary behind our strategic direction and business development, bridging the gap between our customers and engineering teams. His deep passion for coding and web technologies drives the creation of innovative products. If you're at a tech conference, be sure to stop by our booth - you'll most likely meet Bjoern in person. With an advanced graduate degree (Dipl. Inf.) in Computer Science, specializing in AI, from the University of Bremen, Bjoern brings significant expertise to his role. In his spare time, Bjoern enjoys running, paragliding, mountain biking, and playing the piano. - [LinkedIn](https://www.linkedin.com/in/bjoernmeyer/) - [X](https://x.com/txbjoern) - [GitHub](https://github.com/bjoerntx) --- ## Related Posts - [An Ultimate Guide to Mail Merge with MS Word Documents in C#](https://www.textcontrol.com/blog/2023/06/07/an-ultimate-guide-to-mail-merge-with-ms-word-documents-in-csharp/llms.txt) - [Combining MailMerge and Table of Contents](https://www.textcontrol.com/blog/2022/03/22/combining-mailmerge-and-table-of-contents/llms.txt) - [Merging Form Fields using the MailMerge Class](https://www.textcontrol.com/blog/2022/02/21/merging-form-fields-using-the-mailmerge-class/llms.txt) - [MailMerge: Rendering Conditional Table Rows](https://www.textcontrol.com/blog/2022/02/17/mailmerge-rendering-conditional-table-rows/llms.txt) - [MailMerge: Conditional Table Cell Colors using Filter Instructions](https://www.textcontrol.com/blog/2019/06/06/mailmerge-conditional-table-cell-colors-using-filter-instructions/llms.txt) - [MailMerge: Using Filters to Remove Unwanted Rows](https://www.textcontrol.com/blog/2019/06/04/mailmerge-using-filters-to-remove-unwanted-rows/llms.txt) - [Different Ways to Create Documents using Text Control Products](https://www.textcontrol.com/blog/2017/10/17/ways-to-create-documents-using-text-control-products/llms.txt) - [TXTextControl.Markdown.Core 34.1.0-beta: Work with Full Documents, Selection, and SubTextParts](https://www.textcontrol.com/blog/2026/04/14/txtextcontrol-markdown-core-34-1-0-beta-work-with-full-documents-selection-and-subtextparts/llms.txt) - [TX Spell .NET 11.0 SP1 is Now Available: What's New in the Latest Version](https://www.textcontrol.com/blog/2026/04/08/tx-spell-net-11-0-sp1-is-now-available/llms.txt) - [TX Text Control 34.0 SP2 is Now Available: What's New in the Latest Version](https://www.textcontrol.com/blog/2026/02/18/tx-text-control-34-0-sp2-is-now-available/llms.txt) - [TX Text Control 34.0 SP1 is Now Available: What's New in the Latest Version](https://www.textcontrol.com/blog/2025/12/03/tx-text-control-34-0-sp1-is-now-available/llms.txt) - [Introducing TX Text Control 34.0: Your Next Leap in Document Processing](https://www.textcontrol.com/blog/2025/11/10/introducing-tx-text-control-34-0-your-next-leap-in-document-processing/llms.txt) - [Sneak Peek: TX Text Control 34.0 Coming November 2025](https://www.textcontrol.com/blog/2025/10/02/sneak-peek-tx-text-control-34-0-coming-november-2025/llms.txt) - [TX Text Control 33.0 SP3 is Now Available: What's New in the Latest Version](https://www.textcontrol.com/blog/2025/08/14/tx-text-control-33-0-sp3-is-now-available/llms.txt) - [TX Text Control 33.0 SP2 is Now Available: What's New in the Latest Version](https://www.textcontrol.com/blog/2025/06/18/tx-text-control-33-0-sp2-is-now-available/llms.txt) - [Document Lifecycle Optimization: Leveraging TX Text Control's Internal Format](https://www.textcontrol.com/blog/2025/05/16/document-lifecycle-optimization-leveraging-tx-text-controls-internal-format/llms.txt) - [Expert Implementation Services for Legacy System Modernization](https://www.textcontrol.com/blog/2025/05/07/expert-implementation-services-for-legacy-system-modernization/llms.txt) - [Service Pack Releases: What's New in TX Text Control 33.0 SP1 and 32.0 SP5](https://www.textcontrol.com/blog/2025/05/07/service-pack-releases-whats-new-in-tx-text-control-33-0-sp1-and-32-0-sp5/llms.txt) - [Top 5 Real-World Applications for TX Text Control Document Processing Libraries](https://www.textcontrol.com/blog/2025/04/01/top-5-real-world-applications-for-tx-text-control-document-processing-libraries/llms.txt) - [DWX Developer Week Moves to Mannheim - And Text Control Is on Board!](https://www.textcontrol.com/blog/2025/03/19/dwx-developer-week-moves-to-mannheim-and-tx-text-control-is-on-board/llms.txt) - [The Wait is Over: TX Text Control for Linux is Officially Here](https://www.textcontrol.com/blog/2025/03/12/the-wait-is-over-tx-text-control-for-linux-is-officially-here/llms.txt) - [Full .NET 9 Support in Text Control .NET Components for ASP.NET Core, Windows Forms, and WPF](https://www.textcontrol.com/blog/2024/11/11/full-net-9-support-in-text-control-net-components-for-asp-net-core-windows-forms-and-wpf/llms.txt) - [Toggle Field Codes in TX Text Control](https://www.textcontrol.com/blog/2024/11/07/toggle-field-codes-in-tx-text-control/llms.txt) - [TX Text Control 32.0 Service Pack 4 Released](https://www.textcontrol.com/blog/2024/09/02/tx-text-control-32-0-service-pack-4-released/llms.txt) - [Service Pack 3: MailMerge Supports SVG Images](https://www.textcontrol.com/blog/2024/04/29/service-pack-3-mailmerge-supports-svg-images/llms.txt)