{
    "summary": [
        {
            "name": "tk_messages",
            "title": "工单往来消息",
            "primary": ["id"],
            "catelog": "entity"
        }
    ],
    "fields": [
        {"name": "id", "title": "主键ID", "type": "str", "length": 32, "nullable": "no"},
        {"name": "ticket_id", "title": "工单ID", "type": "str", "length": 32, "nullable": "no"},
        {"name": "sender_type", "title": "发送方类型", "type": "str", "length": 16, "nullable": "no"},
        {"name": "sender_id", "title": "发送人ID", "type": "str", "length": 32},
        {"name": "sender_role", "title": "发送时角色", "type": "str", "length": 64},
        {"name": "content", "title": "消息正文", "type": "longtext"},
        {"name": "attachments", "title": "附件JSON", "type": "text"},
        {"name": "visibility", "title": "可见性", "type": "str", "length": 16, "nullable": "no", "default": "customer"},
        {"name": "created_at", "title": "创建时间", "type": "timestamp", "nullable": "no"}
    ],
    "indexes": [
        {"name": "idx_tkm_ticket", "idxtype": "index", "idxfields": ["ticket_id", "created_at"]},
        {"name": "idx_tkm_vis", "idxtype": "index", "idxfields": ["visibility"]}
    ],
    "codes": [
        {"field": "sender_type", "table": "appcodes_kv", "valuefield": "k", "textfield": "v", "cond": "parentid='tk_sender_type'"},
        {"field": "visibility", "table": "appcodes_kv", "valuefield": "k", "textfield": "v", "cond": "parentid='tk_visibility'"}
    ]
}