(1.21.4) (Client-side) How do I intercept and modify messages sent by the player?

[DanPlus6]

Description

Let's say the player types in chat, "The foo is looking nice today!", how do I intercept this message and modify it to replace "foo" with "bar" so that the message that gets sent out is "The bar is looking nice today!" instead?

[modmuss50]

Hey, you can use the ServerMessageDecoratorEvent in the conent phase, see the following example from one of the test mods. This example returns replaces the whole message, but you can just as easily replace or add to the message.

https://github.com/FabricMC/fabric/blob/6da4c195991ba0dbdb29f2537bd993b0975830a8/fabric-message-api-v1/src/testmod/java/net/fabricmc/fabric/test/message/ChatTest.java#L50-L56

[modmuss50]

Just seen you wanted this for the client side, and not the server. On the client you will want ClientSendMessageEvents.MODIFY_CHAT like so:

https://github.com/FabricMC/fabric/blob/6da4c195991ba0dbdb29f2537bd993b0975830a8/fabric-message-api-v1/src/testmodClient/java/net/fabricmc/fabric/test/message/client/ChatTestClient.java#L54-L61

[DanPlus6]

Thank you so much!

[FlukeBTW]

@Dave-New-Dev did it work as you expected?

[DanPlus6]

yes :D

[DereC4]

here in 2026 reading the docs, thanks for this