Minecraft datapack advancement predicate for horse's items (enchanted saddle)

Question

I am trying to make a datapack that uses the started_riding advancement trigger. I need help fleshing out the details of how to make the predicate that I want. I want the advancement to only be given if a player starts riding a horse that has a saddle with a specific enchantment on it (Loyalty).

Summary of work done to figure it out on my own:

I have been able successfully filter for the horse wearing armor with the enchantment as:

"predicate": {
  "vehicle": {
    "type": "minecraft:horse",
    "equipment": {
      "chest": {
        "items": [
          "leather_horse_armor",
          "iron_horse_armor",
          "golden_horse_armor",
          "diamond_horse_armor"
        ],
        "enchantments": [
          {
            "enchantment": "loyalty",
            "levels": 3
          }
        ]
      }
    }
  }
}

but I have not seen a equivalent field to equipment.chest.items that will let me access the saddle item through the criteria interface. So I believe I have to go through nbt tags, but I have not been able to get it to work. My most recent attempts were

"predicate": {
  "vehicle": {
    "type": "horse",
    "nbt": "{SaddleItem:{id:\"saddle\", tag:{Enchantments:[{id:\"loyalty\", lvl:3s}]}}}"
  }
}

I also tried

"nbt": "{\"SaddleItem\":{\"id\":\"saddle\", \"tag\":{\"Enchantments\":[{\"id\":\"loyalty\", \"lvl\":3s}]}}}"

because I am still not clear on the escape quoting rules, but neither of those worked. When I get the horse's SaddleItem data in game (via /data get entity @e[type=horse,sort=nearest,limit=1] SaddleItem) I get this object back:

{
  id:"minecraft:saddle", 
  Count:1b, 
  tag: {
    RepairCost: 1,
    Enchantments: [
      {
        lvl: 3s,
        id: "minecraft:loyalty"
      }
    ]
  }
}

and that seems to mirror what I was inputting as the nbt data so I'm not sure where to go from there. I did also try adding in the Count and RepairCost fields but that didn't seem to help and I think I shouldn't need to?

Any guidance on how to form the started_riding predicate to select for a horse wearing a loyalty-enchanted saddle is greatly appreciated.

Answer 1

Seems that I was missing the minecraft: namespace identifier before the saddle and loyalty id fields. It seems like specifying the default minecraft namespace is not necessary for advancement fields but is for nbt tags.

A functioning nbt predicate to detect the enchanted saddle is:

"nbt": "{SaddleItem:{id:\"minecraft:saddle\", tag:{Enchantments:[{id:\"minecraft:loyalty\", lvl:3s}]}}}"