# Message Upcasters Message Upcasters will modify raw event data before it is rebuilt back into a message. This is useful in case you want to change the format of event data if you screwed up or if you learned something new. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.sonsofphp.com/components/event-sourcing/event-messages/message-upcasters.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.