minetest-flow/doc/inventory.md

Using a form as an inventory

Consider using Sway instead if you want to use flow as an inventory replacement while still having some way for other mods to extend the inventory.

A form can be set as the player inventory. Flow internally generates the formspec and passes it to player:set_inventory_formspec(). This will completely replace your inventory and isn't compatible with inventory mods like sfinv.

local example_inventory = flow.make_gui(function (player, context)
    return gui.Label{ label = "Inventory goes here!" }
end)
minetest.register_on_joinplayer(function(player)
    example_inventory:set_as_inventory_for(player)
end)

Like with the show_hud function, update* functions don't do anything, so to update it, call set_as_inventory_for again with the new context. If the context is not provided, it will reuse the existing context.

example_inventory:set_as_inventory_for(player, new_context)

While the form will of course be cleared when the player leaves, if you'd like to unset the inventory manually, call :unset_as_inventory_for(player), analogue to close_hud:

example_inventory:unset_as_inventory_for(player)

This will set the inventory formspec string to "" and stop flow from processing inventory formspec input.