{
  "name": "Attachment",
  "type": "object",
  "properties": {
    "id": {
      "$ref": "_id.json"
    },
    "file": {
      "format": "uri",
      "type": "string"
    },
    "attachable_type": {
      "pattern": "(Topic|Message)",
      "type": "string"
    },
    "attachable_id": {
      "$ref": "_id.json"
    },
    "created_at": {
      "$ref": "_datetimestamp.json"
    },
    "updated_at": {
      "$ref": "_datetimestamp.json"
    }
  },
  "required": [
    "id",
    "file",
    "attachable_type",
    "attachable_id",
    "created_at",
    "updated_at"
  ]
}