Item_model in loot tables

Hello I am working with the item_model tag on items to have them display as custom items and its working great. I have all of my custom items working how I want but when wanting to spawn them in loot tables I am able to set all the nbt how I want but I cant quite get the item_model to be set. I cant see any function to apply an item_model onto it. This is what I have 
          "type": "minecraft:item",
          "name": "minecraft:sugar",
          "weight": 2,
          "functions": [
            {
              "function": "set_name",
              "name": {
                "text": "Shulkers Grace",
                "italic": false,
                "color": "yellow"
              }
            },
            {
              "function": "set_attributes",
              "modifiers": [
                {
                  "attribute": "minecraft:safe_fall_distance",
                  "id": "shulkers_grace_speed",
                  "amount": 1,
                  "operation": "add_value",
                  "slot": "offhand"
                }
              ]
            }
          ]
        }```