cookbook • http• context

使用在另一个流程中捕获的数据响应

问题

你想要使用由另一个流程捕获的数据来响应HTTP请求。

解决方案

使用 flow context 存储数据，以便在HTTP流程中检索。

示例

[{"id":"92eaf6c0.6d1508","type":"inject","z":"3045204d.cfbae","name":"","topic":"","payload":"","payloadType":"date","repeat":"","crontab":"","once":false,"x":100,"y":480,"wires":[["8055b557.7faa48"]]},{"id":"8055b557.7faa48","type":"change","z":"3045204d.cfbae","name":"存储时间","rules":[{"t":"set","p":"timestamp","pt":"flow","to":"payload","tot":"msg"}],"action":"","property":"","from":"","to":"","reg":false,"x":270,"y":480,"wires":[[]]},{"id":"93bf2335.6c40e","type":"http in","z":"3045204d.cfbae","name":"","url":"/hello-data","method":"get","swaggerDoc":"","x":120,"y":520,"wires":[["9e3aa25e.61c56"]]},{"id":"9e3aa25e.61c56","type":"change","z":"3045204d.cfbae","name":"复制时间","rules":[{"t":"set","p":"timestamp","pt":"msg","to":"timestamp","tot":"flow"}],"action":"","property":"","from":"","to":"","reg":false,"x":310,"y":520,"wires":[["f2c385a.f0d3c78"]]},{"id":"f2c385a.f0d3c78","type":"template","z":"3045204d.cfbae","name":"页面","field":"payload","fieldType":"msg","format":"handlebars","syntax":"mustache","template":"<html>\n    <head></head>\n    <body>\n        <h1>时间: {{ timestamp }}</h1>\n    </body>\n</html>","x":470,"y":520,"wires":[["def756a1.2108a8"]]},{"id":"def756a1.2108a8","type":"http response","z":"3045204d.cfbae","name":"","x":610,"y":520,"wires":[]}]

[~]$ curl http://localhost:1880/hello-data
<html>
    <head></head>
    <body>
        <h1>时间: 1480201022517</h1>
    </body>
</html>

讨论

在流程中存储和检索数据的方式有很多种。例如，使用一个外部数据库。

Node-RED提供了 flow context 作为一个简单的键值存储，所有在同一选项卡上的节点都可以访问。

上述示例将由一个 Inject 节点生成的时间戳存储到 flow context 中，使用一个 Change 节点。处理HTTP请求的流程随后使用另一个 Change 节点来检索该值，将其附加到消息中，然后传递给一个 Template 节点以生成响应。

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Node-RED: 用于事件驱动应用程序的低代码编程。