This mod provided a Gui that you can make datapack more easier! You only need to drag items into corresponding slots and click confirm button to generate a recipe in your save's directory.
Both client side and server side need to install it
Open GUI by command. (Only operator-permission)
/dprm Open menu GUI
The recipes you created will be saved in datapack at "saves/<save name>/datapacks/" directory.
After adding the recipes, you need to input "/reload" command manually to let your datapack effect in your game.