end_city_treasure.json

{
    "rolls": {
        "min": 2,
        "max": 6
    },
    "items": [
        {
            "item": "minecraft:diamond",
            "weight": 5,
            "functions": [
                {
                    "function": "set_count",
                    "count": {
                        "min": 2,
                        "max": 7
                    }
                }
            ]
        },
        {
            "item": "minecraft:iron_ingot",
            "weight": 10,
            "functions": [
                {
                    "function": "set_count",
                    "count": {
                        "min": 4,
                        "max": 8
                    }
                }
            ]
        },
        {
            "item": "minecraft:gold_ingot",
            "weight": 15,
            "functions": [
                {
                    "function": "set_count",
                    "count": {
                        "min": 2,
                        "max": 7
                    }
                }
            ]
        },
        {
            "item": "minecraft:emerald",
            "weight": 2,
            "functions": [
                {
                    "function": "set_count",
                    "count": {
                        "min": 2,
                        "max": 6
                    }
                }
            ]
        },
        {
            "item": "minecraft:beetroot_seeds",
            "weight": 5,
            "functions": [
                {
                    "function": "set_count",
                    "count": {
                        "min": 1,
                        "max": 10
                    }
                }
            ]
        },
        {
            "item": "minecraft:saddle",
            "weight": 3
        },
        {
            "item": "minecraft:iron_horse_armor",
            "weight": 1
        },
        {
            "item": "minecraft:golden_horse_armor",
            "weight": 1
        },
        {
            "item": "minecraft:diamond_horse_armor",
            "weight": 1
        },
        {
            "item": "minecraft:diamond_sword",
            "weight": 3,
            "functions": [
                {
                    "function": "enchant_with_levels",
                    "treasure": true,
                    "levels": {
                        "min": 20,
                        "max": 39
                    }
                }
            ]
        },
        {
            "item": "minecraft:diamond_boots",
            "weight": 3,
            "functions": [
                {
                    "function": "enchant_with_levels",
                    "treasure": true,
                    "levels": {
                        "min": 20,
                        "max": 39
                    }
                }
            ]
        },
        {
            "item": "minecraft:diamond_chestplate",
            "weight": 3,
            "functions": [
                {
                    "function": "enchant_with_levels",
                    "treasure": true,
                    "levels": {
                        "min": 20,
                        "max": 39
                    }
                }
            ]
        },
        {
            "item": "minecraft:diamond_leggings",
            "weight": 3,
            "functions": [
                {
                    "function": "enchant_with_levels",
                    "treasure": true,
                    "levels": {
                        "min": 20,
                        "max": 39
                    }
                }
            ]
        },
        {
            "item": "minecraft:diamond_helmet",
            "weight": 3,
            "functions": [
                {
                    "function": "enchant_with_levels",
                    "treasure": true,
                    "levels": {
                        "min": 20,
                        "max": 39
                    }
                }
            ]
        },
        {
            "item": "minecraft:diamond_pickaxe",
            "weight": 3,
            "functions": [
                {
                    "function": "enchant_with_levels",
                    "treasure": true,
                    "levels": {
                        "min": 20,
                        "max": 39
                    }
                }
            ]
        },
        {
            "item": "minecraft:diamond_shovel",
            "weight": 3,
            "functions": [
                {
                    "function": "enchant_with_levels",
                    "treasure": true,
                    "levels": {
                        "min": 20,
                        "max": 39
                    }
                }
            ]
        },
        {
            "item": "minecraft:iron_sword",
            "weight": 3,
            "functions": [
                {
                    "function": "enchant_with_levels",
                    "treasure": true,
                    "levels": {
                        "min": 20,
                        "max": 39
                    }
                }
            ]
        },
        {
            "item": "minecraft:iron_boots",
            "weight": 3,
            "functions": [
                {
                    "function": "enchant_with_levels",
                    "treasure": true,
                    "levels": {
                        "min": 20,
                        "max": 39
                    }
                }
            ]
        },
        {
            "item": "minecraft:iron_chestplate",
            "weight": 3,
            "functions": [
                {
                    "function": "enchant_with_levels",
                    "treasure": true,
                    "levels": {
                        "min": 20,
                        "max": 39
                    }
                }
            ]
        },
        {
            "item": "minecraft:iron_leggings",
            "weight": 3,
            "functions": [
                {
                    "function": "enchant_with_levels",
                    "treasure": true,
                    "levels": {
                        "min": 20,
                        "max": 39
                    }
                }
            ]
        },
        {
            "item": "minecraft:iron_helmet",
            "weight": 3,
            "functions": [
                {
                    "function": "enchant_with_levels",
                    "treasure": true,
                    "levels": {
                        "min": 20,
                        "max": 39
                    }
                }
            ]
        },
        {
            "item": "minecraft:iron_pickaxe",
            "weight": 3,
            "functions": [
                {
                    "function": "enchant_with_levels",
                    "treasure": true,
                    "levels": {
                        "min": 20,
                        "max": 39
                    }
                }
            ]
        },
        {
            "item": "minecraft:iron_shovel",
            "weight": 3,
            "functions": [
                {
                    "function": "enchant_with_levels",
                    "treasure": true,
                    "levels": {
                        "min": 20,
                        "max": 39
                    }
                }
            ]
        }
    ]
}

I'm wondering when the loot tables are invoked for chests? The first time you open them? When they are setblock'd in? I'm assuming it can't be during generation, because that wouldn't work for custom maps...

@Arcensoth The first time you open them. https://twitter.com/Dinnerbone/status/656460301571858432

@madisotenurm Thanks! That's great! Exactly what I was hoping for.