LINQ Reporting Engine or Mail Merge

Aspose.Words provides two solutions for automatic filling template documents with data: Mail Merge and LINQ Reporting Engine. But what is the difference between the two and which solution is better to choose? Let us make a closer look at each.

Mail Merge Features

As well as the most of Aspose.Words features, Mail Merge mimics the Microsoft Word feature with the same name. Therefore, a typical Mail Merge template consists of common document content, merge fields to be replaced with data, and fields of other types supported by Microsoft Word defining additional logic for building a result document. For example, a Mail Merge template for order could look as follows.

Key features provided by Mail Merge are as follows:

• Printing and formatting data values
• Basic calculations
• Dynamic insertion of images and documents
• Support of repetitive document regions (data bands)
• Inclusion of document parts depending on conditions
• Built-in support for objects mimicking ADO.NET in Java as data sources (any custom data source can be supported by implementing the IMailMergeDataSource interface)

Overall, Mail Merge is a good way to go if you are never going to use features beyond the scope of Mail Merge, or you have to deal with Microsoft Word Mail Merge templates. However, being tied with and limited by Microsoft Word behavior, Mail Merge cannot be easily extended to cover every specific scenario, and this is where LINQ Reporting Engine stands out.

LINQ Reporting Engine Features

In contrast to Mail Merge, the concept of the LINQ Reporting Engine was born within Aspose.Words and is not tied with any Microsoft Word legacy. The engine uses its own template syntax based on plain-text tags, which can be one of the reasons to switch to its usage if working with Microsoft Word fields is too complex for you or your users creating templates. For example, an alternative LINQ Reporting Engine template for an order looks as follows.

However, the major advantage of the engine is its out-of-the-box support of many features missing in Mail Merge. The following are the key ones:

• Support of multiple data sources (including of different types)
• Built-in support of more data source types: Custom Java objects, objects mimicking ADO.NET in Java, JSON, XML, CSV
• Using of C#-based expression syntax (extended for ADO.NET and other data sources, and adapted for Java) directly in templates
• Using of LINQ extension methods for data manipulations directly in templates
• Dynamic building of charts
• Built-in support of HTML insertion
• Dynamic merging of table cells
• Controlling of how template syntax errors are reported

The good news is that LINQ Reporting Engine can be further extended to fulfill almost any specific need. So if you face any issue while implementing your specific requirement using the engine, please feel free to contact us at our Free Support forum, and we will gladly provide you a solution based on existing features of the engine or introduce a new feature to address your need.

See Also

• List of fields supported by Microsoft Word

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FAQ

1. Q: What is the main difference between Mail Merge and LINQ Reporting Engine in Aspose.Words for Java?
   A: Mail Merge replicates Microsoft Word’s native mail‑merge functionality and works with merge fields defined in the document. LINQ Reporting Engine uses its own plain‑text tag syntax, is not bound to Word’s legacy behavior, and provides richer features such as multiple data sources, LINQ expressions, and dynamic chart generation.

2. Q: Can I combine Mail Merge and LINQ Reporting Engine in the same document?
   A: Yes. You can use Mail Merge for simple field replacements and LINQ Reporting Engine tags for more complex scenarios (e.g., charts or HTML). Process the LINQ tags first with ReportingEngine, then execute Document.mailMerge().execute(...) for any remaining merge fields.

3. Q: Which solution is better for inserting images dynamically?
   A: Both solutions support image insertion, but LINQ Reporting Engine offers a more concise syntax. Example with LINQ tags: <<image [Product.ImageUrl]>>. With Mail Merge you would need to implement IMailMergeDataSource and handle the FieldMergingCallback to replace the image field.

4. Q: How does LINQ Reporting Engine handle multiple data sources compared to Mail Merge?
   A: LINQ Reporting Engine can bind JSON, XML, CSV, custom Java objects, and ADO.NET‑like data sources simultaneously within a single template. Mail Merge is limited to a single data source per execute call; to use multiple sources you must run separate execute calls or write custom code.

5. Q: Is there a performance difference between the two approaches?
   A: For simple, single‑source scenarios Mail Merge is slightly faster because it performs straightforward field replacement. When complex data manipulation, multiple sources, or large templates are involved, LINQ Reporting Engine often outperforms Mail Merge because it avoids repeated document passes and leverages optimized LINQ operations.