How to get parameter value in HTTP request node using NodeRed
I am trying to get the URL parameter from a request and pass it into another URL request.
So my initial request from the the URL is something like: http://xxxxxxx.mybluemix.net/getFlow?parameterCd=00060,00065,00010
And I was to use the "parameterCd" values in another request in the http request node in my flow.
I thought something like this might work - see msg.payload.parameterCd http://waterservices.usgs.gov/nwis/iv/?format=json,1.1&sites=USGS:14330000¶meterCd={{msg.payload.parameterCd}}&siteType=ST
Any ideas? Maybe this is not supported yet.
Hi @BrianIBM
as per the sidebar docs of the HTTP In node, the incoming request is available under msg.req which is the underlying Express request object.
From their docs, the piece you want is msg.req.query. So, in your instance:
msg.req.query.parameterCd
Nick
I was not able to get that to work in the HTTP in node.
I ended up creating a function that creates the entire URL using the msg.req.query. I then set the "url" on the msg.
var url= "http://waterservices.usgs.gov/nwis/iv/?format=json,1.1&siteType=ST&sites=" + msg.req.query.sites + "¶meterCd=" + msg.req.query.parameterCd;
msg.url = url;
return msg;
And in the HTTP in node I just leave the URL field empty and it gets the value from function.
Here is JSON node-red code: [{"id":"b348514d.4cb7b","type":"inject","name":"","topic":"","payload":"{\"parameterCd\":\"00060,00065,00010\"}","payloadType":"string","repeat":"","crontab":"","once":false,"x":118,"y":194,"z":"459cde3c.ba632","wires":[[]]},{"id":"cc1625f2.33e9d8","type":"http request","name":"getRiverFlow","method":"GET","ret":"obj","url":"","x":420,"y":194,"z":"459cde3c.ba632","wires":[["e6c6de1f.19392","5c81ea7d.a37e14"]]},{"id":"e6c6de1f.19392","type":"debug","name":"","active":false,"console":"false","complete":"false","x":452,"y":103,"z":"459cde3c.ba632","wires":[]},{"id":"5c81ea7d.a37e14","type":"function","name":"getFlow","func":"var data = \"{\";\n\nvar timeSeries = msg.payload.value.timeSeries;\n\nvar siteName = \"\";\n\nif (timeSeries.length > 0)\n{\n\tsiteName = timeSeries[0].sourceInfo.siteName;\n\t\n\tdata+= \"\\\"siteName\\\":\\\"\" + siteName + \"\\\"\";\n}\n\nfor (i in timeSeries)\n{\n\tvar varName = timeSeries[i].variable.variableName;\n\t\n\tif (varName.indexOf(\"Temp\") >= 0)\n\t{\n\t\tvarName = \"temp\";\t\n\t}\n\telse if (varName.indexOf(\"flow\") >= 0)\n\t{\n\t\tvarName = \"flow\";\n\t}\n\telse if (varName.indexOf(\"Gage\") >= 0)\n\t{\n\t\tvarName = \"gage\";\n\t}\n\t\n\tdata += \", \\\"\" + varName + \"\\\":\"; \n\t\n\tdata += \"\\\"\" + timeSeries[i].values[0].value[0].value + \"\\\"\";\n}\n\ndata += \"}\"\n\nmsg.payload = data;\n\nreturn msg;","outputs":1,"x":664,"y":193,"z":"459cde3c.ba632","wires":[["aed82af.f5127d8","d65fdd0d.29a02"]]},{"id":"aed82af.f5127d8","type":"debug","name":"","active":true,"console":"false","complete":"false","x":790,"y":96,"z":"459cde3c.ba632","wires":[]},{"id":"99498e0d.66b67","type":"http in","name":"getFlow","url":"/getFlow","method":"get","x":109,"y":356,"z":"459cde3c.ba632","wires":[["56b99498.a9466c"]]},{"id":"d65fdd0d.29a02","type":"http response","name":"","x":882,"y":192,"z":"459cde3c.ba632","wires":[]},{"id":"56b99498.a9466c","type":"function","name":"createUSGSURL","func":"//sites=USGS:14330000\n//parameterCd=00060,00065,00010\n\nvar url= \"http://waterservices.usgs.gov/nwis/iv/?format=json,1.1&siteType=ST&sites=\" + msg.req.query.sites + \"¶meterCd=\" + msg.req.query.parameterCd;\n\nmsg.url = url;\n\nreturn msg;","outputs":1,"x":278,"y":296,"z":"459cde3c.ba632","wires":[["cc1625f2.33e9d8"]]}]
Getting Nick's suggestion to work provides a simple and elegant solution. Just add a function node between the HTTP request and response nodes:
msg.payload=msg.req.query.parameterCd; return msg;
This will emit the required value of parameterCd in response too: http://xxxxxxx.mybluemix.net/getFlow?parameterCd=00060
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