Search code examples
jsonnode-red

extract values from json red node

"{"values":[{"key": "id", "value": 171},{"key": "counter", "value": 0},{"key": "temperature", "value": 2561},{"key": "x_axis", "value": -223},{"key": "y_axis", "value": -256},{"key": "z_axis", "value": 246},{"key": "battery", "value": 2817}]}"

I have a device (zolertia z1) sending in json data using MQTT and I'm using a function in node-RED to extract values but i keep getting errors my code

return {values: msg.values.temperature};

error :

function : (error)
"TypeError: Cannot read property 'temperature' of undefined"
Solution

  • The output from the MQTT node is a String not a JSON object.

    enter image description here

    Run the output through a JSON node to convert the string to a JSON object before passing it to your function node.

    Also the object will be set as the msg.payload.values not msg.values