First you should create a separate db and user in influxdb to practice with. Sending the wrong values to a measurement can really screw things up. I have this flow that checks message structure. It’s a matter of routing what you save in a change node to the correct message position.
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It must be an object containing fieldName:fieldValue pairs or a single value (which would be written to the `value` field name).')\n return\n} else {\n // Otherwise, we always use 'value' as the default field name\n fields = {'value': msg.payload}\n}\n\nconst lstFields = Object.keys(fields)\n\n// check to make sure that there is a value field name - if not, continue but with a warning\nif ( ! lstFields.includes('value') ) {\n // Lets us turn off the warning if we know what we are doing :-)\n if ( msg.noValueField !== true )\n node.warn('Default field name \"vaue\" not present, was that deliberate? Set msg.noValueField=true or use the `value` field name to avoid this msg')\n}\n\n// check to make sure that all field values are numeric - if not, exit with a warning\nlet allNumeric = true\nlstFields.forEach( key => {\n // I use On/Off for simple switch values in MQTT but these are not useful\n // in InfluxDB, so translate them to ON=1 and OFF=0 (ignoring case).\n try {\n if ( fields[key].toLowerCase() === 'on' ) fields[key] = 1\n if ( fields[key].toLowerCase() === 'off' ) fields[key] = 0\n } catch (e) {}\n\n // then check to make sure the field is actually a number\n if ( parseFloat(fields[key]) !== fields[key] ) {\n node.error(`Field msg.payload.${key} is not numeric. 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If present, it **MUST** be an object containing tagName:tagValue pairs.\n\nWe will ALWAYS use the \"array containing two objects\" payload\nOR the singe Object payload (if no tags being used).\n\n## Tests\n* _SUCCESS_: \n `msg={\"payload\":{\"fieldName1\":10,\"value\":15},\"tags\":{\"tagName1\":\"tagname1Value\"},\"measure\":\"myMeasure1\"}`\n* _SUCCESS_ (payload converted to `{\"value\":16}`): \n `msg={\"payload\":16,\"tags\":{\"tagName1\":\"tagname1Value\"},\"measure\":\"myMeasure2\"}`\n* _SUCCESS_ (no tags): \n `msg={\"payload\":16,\"measure\":\"myMeasure2\"}`\n* _SUCCESS_ (but warning issued, no value field): \n `msg={\"payload\":{\"fieldName2\":17},\"tags\":{\"tagName1\":\"tagname1Value\"},\"measure\":\"myMeasure3\"}`\n* _SUCCESS_ (value \"On\" converted to 1): \n `msg={\"payload\":\"On\",\"measure\":\"myMeasure4\"}`\n* _???_ (missing tags for a measure with tags): \n `msg={\"payload\":\"On\",\"measure\":\"myMeasure1\"}`\n* _FAIL_: No `msg.measure`\n* _FAIL_: `msg.payload` is an 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