What is Base64 encoding and decoding? On a very high level: it is a method of converting binary data to ASCII text and the ASCII text back again to binary. There are many articles online on how this works technically but this article will explain the basics and how Base64 encoding and decoding is used in Dynamics 365 Finance and Operations (F&O).

For example, if you attach a spreadsheet or other binary file like a PDF document to an email. The binary file is converted to ASCII text using Base64 encoding and is embedded in the message body of the email as text. When the email message is received by the recipient, the email application used to view the email message, detects that there is a file attached embedded as text and converts the text back to binary so that the attachment can be downloaded as a file. Most email applications support previewing attachments, but will have to convert the attachments from text to binary on the fly before being able to display the contents of the file.

So, how does Base64 encoding and decoding relate to F&O? It is frequently used in the standard application and also by developers when using the SysOperation framework just to mention just a few examples.

Code example

In a SysOperation contract class, the SysOperation framework allows a Query object to be used to query data for the operation. Because the related operation can also be run in "batch", in other words in "unattended" mode without an user interface, the Query object of the class needs to be saved to the database so that the operation can be executed by the batch framework and use the exact same query object that was specified by the user when adding the operation to batch. In other words, the system saves all query filters, joins and other changes to the query and will then use your exact query when executing in batch.

An instance of an class object cannot be saved to the database. So, how does the system save the object to the database? By using Base64 encoding and decoding. The Query object of the contract class is serialized to a binary object using the "pack" method of the Query class. This method returns a binary representation of the query in a container type. All class variables of the Query object are serialized and converted to a binary object (container). The resulting binary object of the Query object is then Base64 encoded to text. This text can be saved to the database as a regular text field.

When the Query object instance is required by the SysOperation framework, the process is reversed. The text is Base64 decoded to binary, the original Query object with all the specified filters and other changes can then be instantiated by using the binary data to construct a Query object.

1. Class variable for the Base64 encoded text.

2. Code that converts the text back to binary object.

3. Code that converts the binary object to text.