✅ How to Read a Line from a Text File in AX 2012 Using X++

 

📘 Introduction

In Microsoft Dynamics AX 2012, you might need to read data from external files — especially for importing legacy data, processing configurations, or analyzing logs. This blog will guide you through reading a text file line by line using X++ and the .NET CLR Interop functionality available in AX 2012.

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🧰 Use Case

• Reading flat files during data migration.

• Processing structured text (e.g., logs or CSV).

• Reading file-based configuration values during batch job execution.

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🧾 X++ Code Example – Read Text File Line by Line

Here's a working example using System.IO.StreamReader and UTF-8 encoding:

x++
static void ReadTextFileLineByLine(Args _args)
{
    Filename                    filePath = @"C:\ReadFrom\AX2012.txt";
    System.IO.StreamReader      reader;
    System.String               line;
    InteropPermission           perm;
    str                         output;

    // Allow .NET interop
    perm = new InteropPermission(InteropKind::ClrInterop);
    perm.assert();

    try
    {
        reader = new System.IO.StreamReader(filePath, System.Text.Encoding::get_UTF8());

        line = reader.ReadLine();

        while (!System.String::IsNullOrEmpty(line))
        {
            output = line;
            info(strFmt("Read Line: %1", output));

            // Read the next line
            line = reader.ReadLine();
        }

        reader.Close();
        reader.Dispose();
    }
    catch (Exception::CLRError)
    {
        error(AifUtil::getClrErrorMessage());
    }

    CodeAccessPermission::revertAssert();
}

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🔒 Important Notes

• ✅ Use InteropPermission to allow .NET access.

• ✅ Ensure the path C:\ReadFrom\AX2012.txt exists and is accessible to the AOS user.

• ✅ Use CodeAccessPermission::revertAssert() to restore permission scope.

• 🛠️ You can also enhance this by adding file validations, handling empty lines, or filtering specific content.

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💡 Best Practices

Best Practice	Recommendation
File Encoding	Use UTF-8 unless you expect a different encoding format
Error Handling	Always wrap interop in try/catch to prevent unhandled CLR errors
Security	Use InteropPermission for CLR access and revert permission afterwards
Reusability	Encapsulate this logic into a class method or service for future use

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📌 Real-World Usage Scenarios

• Parsing daily order data from vendors in a flat file.

• Reading a settings.txt file before initializing a batch process.

• Logging and audit trail reviews.

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✅ Summary

This post demonstrated how to read a line from a text file in AX 2012 using X++ with the help of .NET Interop. Whether you're importing legacy data or reading configuration files, this technique is highly effective.

Would you like me to also convert this logic for D365FO using StreamReader in a C# class library or implement it with SysOperationFramework?