Post JSON data to a flow

Problem

You want to post JSON data to a flow.

Solution

Use the HTTP In node to listen for POST requests that have their Content-Type set to application/json and access the parsed JSON as properties of msg.payload.

Example

[{"id":"5b98a8ac.a46758","type":"http in","z":"3045204d.cfbae","name":"","url":"/hello-form","method":"post","swaggerDoc":"","x":120,"y":820,"wires":[["bba61009.4459f"]]},{"id":"bba61009.4459f","type":"template","z":"3045204d.cfbae","name":"page","field":"payload","fieldType":"msg","format":"handlebars","syntax":"mustache","template":"<html>\n    <head></head>\n    <body>\n        <h1>Hello {{ payload.name }}!</h1>\n    </body>\n</html>","x":290,"y":820,"wires":[["6ceb930a.93146c"]]},{"id":"6ceb930a.93146c","type":"http response","z":"3045204d.cfbae","name":"","x":430,"y":820,"wires":[]}]
[~]$ curl -X POST -d '{"name":"Nick"}' -H "Content-type: application/json" http://localhost:1880/hello-form
<html>
    <head></head>
    <body>
        <h1>Hello Nick!</h1>
    </body>
</html>

Discussion

When the HTTP In node receives a request with the Content-Type header set to application/json it parses the body of the request and makes the data available under msg.payload:

var name = msg.payload.name;