将消息属性设置为固定值
问题
您想将消息属性设置为固定值。
解决方案
使用 Change 节点设置消息的属性。
示例
[{"id":"d72dc4ce.89b368","type":"inject","z":"535331d8.55c1f","name":"","topic":"","payload":"","payloadType":"date","repeat":"","crontab":"","once":false,"x":140,"y":80,"wires":[["78075f19.e0174"]]},{"id":"78075f19.e0174","type":"change","z":"535331d8.55c1f","name":"","rules":[{"t":"set","p":"payload","pt":"msg","to":"Hello World!","tot":"str"}],"action":"","property":"","from":"","to":"","reg":false,"x":340,"y":80,"wires":[["78dc7c25.b90d54"]]},{"id":"78dc7c25.b90d54","type":"debug","z":"535331d8.55c1f","name":"","active":true,"console":"false","complete":"false","x":550,"y":80,"wires":[]}]
讨论
Change 节点可用于设置消息的属性。
该节点支持设置各种 JavaScript 类型以及一些 Node-RED 特定类型。
- 字符串：
"hello world" - 数字：
42 - 布尔值：
true/false - 时间戳：当前时间，自纪元（1970 年 1 月 1 日）以来的毫秒数
- JSON：一个将被解析为其对象表示的 JSON 字符串
- Buffer：一个 Node.js Buffer 对象
它还支持根据上下文属性、其他消息属性或 JSONata 表达式的值来设置属性。
