Metadata

Node Metadata

The instance of a node in the world normally only contains the three values mentioned in [Nodes]. However, it is possible to insert extra data into a node. It is called "node metadata"; See NodeMetaRef.

Node metadata contains two things:

  • A key-value store
  • An inventory

Some of the values in the key-value store are handled specially:

  • formspec: Defines a right-click inventory menu. See [Formspec].
  • infotext: Text shown on the screen when the node is pointed at

Example: 

  local meta = core.get_meta(pos)
  meta:set_string("formspec",
          "size[8,9]"..
          "list[context;main;0,0;8,4;]"..
          "list[current_player;main;0,5;8,4;]")
  meta:set_string("infotext", "Chest");
  local inv = meta:get_inventory()
  inv:set_size("main", 8*4)
  print(dump(meta:to_table()))
  meta:from_table({
      inventory = {
          main = {[1] = "default:dirt", [2] = "", [3] = "", [4] = "",
                  [5] = "", [6] = "", [7] = "", [8] = "", [9] = "",
                  [10] = "", [11] = "", [12] = "", [13] = "",
                  [14] = "default:cobble", [15] = "", [16] = "", [17] = "",
                  [18] = "", [19] = "", [20] = "default:cobble", [21] = "",
                  [22] = "", [23] = "", [24] = "", [25] = "", [26] = "",
                  [27] = "", [28] = "", [29] = "", [30] = "", [31] = "",
                  [32] = ""}
      },
      fields = {
          formspec = "size[8,9]list[context;main;0,0;8,4;]list[current_player;main;0,5;8,4;]",
          infotext = "Chest"
      }
  })

Item Metadata

Item stacks can store metadata too. See ItemStackMetaRef.

Item metadata only contains a key-value store.

Some of the values in the key-value store are handled specially:

  • description: Set the item stack's description. See also: get_description in itemstack
  • short_description: Set the item stack's short description. See also: get_short_description in itemstack
  • color: A ColorString, which sets the stack's color.
  • palette_index: If the item has a palette, this is used to get the current color from the palette.

Example: 

  local meta = stack:get_meta()
  meta:set_string("key", "value")
  print(dump(meta:to_table()))