# Setting JSON structure
**URL:** https://discourse.nodered.org/t/setting-json-structure/48409
**Category:** General
**Created:** [14 July 2021 14:19 UTC](https://discourse.nodered.org/t/setting-json-structure/48409 "2021-07-14T14:19:30Z")
**Posts on this page:** 7
**Page:** 1
### Author:  [@ScheepersJohan](https://discourse.nodered.org/u/ScheepersJohan)
#### Post date: [14 July 2021 14:19 UTC](https://discourse.nodered.org/t/setting-json-structure/48409/1 "2021-07-14T14:19:30Z")
Hi All,
I am passing a JSON into two function nodes. The function nodes decode my msg.payload.payload\_raw, by first changing it to 'Base64' and and then decode.
Decoder 1
```auto
let data = msg.payload.payload_raw;
let bytes = new Buffer(data,'Base64');
let decoded = context.Decoder(bytes, msg.payload.port);
msg.payload.uplink_message.decoded_payload = decoded;
return msg;
```
Decoder 2
```auto
let data = msg.payload.payload_raw;
let bytes = new Buffer(data,'Base64');
let decoded = context.Decoder(bytes, msg.payload.port);
msg.payload.decoded_payload = decoded;
return msg;
```
The only difference is that in Decoder 1 is "msg.payload.uplink\_message.decoded\_payload = decoded" and in Decoder 2 is "msg.payload.decoded\_payload = decoded"
Function node Decoder 1 error
```auto
function : (error)
"TypeError: Cannot set property 'decoded_payload' of undefined"
```
Why is it doing this?
```auto
[{"id":"67c0cd0e.e13064","type":"function","z":"1f9de5c0.4c944a","name":"Decoder 1","func":"let data = msg.payload.payload_raw;\nlet bytes = new Buffer(data,'Base64');\n\nlet decoded = context.Decoder(bytes, msg.payload.port);\nmsg.payload.uplink_message.decoded_payload = decoded;\nreturn msg;","outputs":1,"noerr":0,"initialize":"context.Decoder = function(bytes, port) {\n // Decode an uplink message from a buffer\n // (array) of bytes to an object of fields.\n var decoded = {};\n\n if (port === 1)\n {\n decoded.type = \"position\";\n \n decoded.latitudeDeg = bytes[0] + bytes[1] * 256 + bytes[2] * 65536 + bytes[3] * 16777216;\n if (decoded.latitudeDeg >= 0x80000000)\n decoded.latitudeDeg -= 0x100000000;\n decoded.latitudeDeg /= 1e7;\n \n decoded.longitudeDeg = bytes[4] + bytes[5] * 256 + bytes[6] * 65536 + bytes[7] * 16777216;\n if (decoded.longitudeDeg >= 0x80000000)\n decoded.longitudeDeg -= 0x100000000;\n decoded.longitudeDeg /= 1e7;\n \n decoded.inTrip = ((bytes[8] & 0x1) !== 0) ? true : false;\n decoded.fixFailed = ((bytes[8] & 0x2) !== 0) ? true : false;\n decoded.headingDeg = (bytes[8] >> 2) * 5.625;\n \n decoded.speedKmph = bytes[9];\n decoded.batV = bytes[10] * 0.025;\n }\n else if (port === 2)\n {\n decoded.type = \"downlink ack\";\n \n decoded.sequence = (bytes[0] & 0x7F);\n decoded.accepted = ((bytes[0] & 0x80) !== 0) ? true : false;\n decoded.fwMaj = bytes[1];\n decoded.fwMin = bytes[2];\n }\n else if (port === 3)\n {\n decoded.type = \"stats\";\n \n decoded.initialBatV = (((bytes[0] & 0xF) !== 0) ? (4.0 + (bytes[0] & 0xF) * 0.100) : null);\n decoded.txCount = 32 * ((bytes[0] >> 4) + (bytes[1] & 0x7F) * 16);\n decoded.tripCount = 32 * ((bytes[1] >> 7) + (bytes[2] & 0xFF) * 2\n + (bytes[3] & 0x0F) * 512);\n decoded.gpsSuccesses = 32 * ((bytes[3] >> 4) + (bytes[4] & 0x3F) * 16);\n decoded.gpsFails = 32 * ((bytes[4] >> 6) + (bytes[5] & 0x3F) * 4);\n decoded.aveGpsFixS = 1 * ((bytes[5] >> 6) + (bytes[6] & 0x7F) * 4);\n decoded.aveGpsFailS = 1 * ((bytes[6] >> 7) + (bytes[7] & 0xFF) * 2);\n decoded.aveGpsFreshenS = 1 * ((bytes[7] >> 8) + (bytes[8] & 0xFF) * 1);\n decoded.wakeupsPerTrip = 1 * ((bytes[8] >> 8) + (bytes[9] & 0x7F) * 1);\n decoded.uptimeWeeks = 1 * ((bytes[9] >> 7) + (bytes[10] & 0xFF) * 2);\n }\n\n return decoded;\n}","finalize":"","libs":[],"x":370,"y":200,"wires":[["7aede05c.a9783"]]}]
```
[admin edit: fixed trailing ticks to backticks]
---
### Author:  [@Steve-Mcl](https://discourse.nodered.org/u/Steve-Mcl)
#### Post date: [14 July 2021 14:36 UTC](https://discourse.nodered.org/t/setting-json-structure/48409/2 "2021-07-14T14:36:16Z")
You have not provided sample data (you only posted the function `Decoder1`)
Select all the relevant nodes before exporting.
---
### Author:  [@Steve-Mcl](https://discourse.nodered.org/u/Steve-Mcl)
#### Post date: [14 July 2021 14:45 UTC](https://discourse.nodered.org/t/setting-json-structure/48409/3 "2021-07-14T14:45:02Z")
Actually, i dont need to see your full flow.
The error is exactly as it states ` Cannot set property 'decoded_payload' of undefined"`
look at the line ...
`msg.payload.uplink_message.decoded_payload = decoded;`
... it is highly probable `uplink_message` is not a property of `msg.payload` so try this instead...
#### Decoder 1
```auto
let data = msg.payload.payload_raw;
let bytes = new Buffer(data,'Base64');
let decoded = context.Decoder(bytes, msg.payload.port);
msg.payload.uplink_message = { decoded_payload : decoded };
return msg;
```
PS
`let bytes = new Buffer(data,'Base64');` is depreciated
you should use `let bytes = Buffer.from( );`
---
### Author:  [@ScheepersJohan](https://discourse.nodered.org/u/ScheepersJohan)
#### Post date: [14 July 2021 14:49 UTC](https://discourse.nodered.org/t/setting-json-structure/48409/5 "2021-07-14T14:49:57Z")
```auto
[{"id":"1f9de5c0.4c944a","type":"tab","label":"Flow 11","disabled":false,"info":""},{"id":"67c0cd0e.e13064","type":"function","z":"1f9de5c0.4c944a","name":"Decoder 1","func":"let data = msg.payload.payload_raw;\nlet bytes = new Buffer(data,'Base64');\n\nlet decoded = context.Decoder(bytes, msg.payload.port);\nmsg.payload.uplink_message.decoded_payload = decoded;\nreturn msg;","outputs":1,"noerr":0,"initialize":"context.Decoder = function(bytes, port) {\n // Decode an uplink message from a buffer\n // (array) of bytes to an object of fields.\n var decoded = {};\n\n if (port === 1)\n {\n decoded.type = \"position\";\n \n decoded.latitudeDeg = bytes[0] + bytes[1] * 256 + bytes[2] * 65536 + bytes[3] * 16777216;\n if (decoded.latitudeDeg >= 0x80000000)\n decoded.latitudeDeg -= 0x100000000;\n decoded.latitudeDeg /= 1e7;\n \n decoded.longitudeDeg = bytes[4] + bytes[5] * 256 + bytes[6] * 65536 + bytes[7] * 16777216;\n if (decoded.longitudeDeg >= 0x80000000)\n decoded.longitudeDeg -= 0x100000000;\n decoded.longitudeDeg /= 1e7;\n \n decoded.inTrip = ((bytes[8] & 0x1) !== 0) ? true : false;\n decoded.fixFailed = ((bytes[8] & 0x2) !== 0) ? true : false;\n decoded.headingDeg = (bytes[8] >> 2) * 5.625;\n \n decoded.speedKmph = bytes[9];\n decoded.batV = bytes[10] * 0.025;\n }\n else if (port === 2)\n {\n decoded.type = \"downlink ack\";\n \n decoded.sequence = (bytes[0] & 0x7F);\n decoded.accepted = ((bytes[0] & 0x80) !== 0) ? true : false;\n decoded.fwMaj = bytes[1];\n decoded.fwMin = bytes[2];\n }\n else if (port === 3)\n {\n decoded.type = \"stats\";\n \n decoded.initialBatV = (((bytes[0] & 0xF) !== 0) ? (4.0 + (bytes[0] & 0xF) * 0.100) : null);\n decoded.txCount = 32 * ((bytes[0] >> 4) + (bytes[1] & 0x7F) * 16);\n decoded.tripCount = 32 * ((bytes[1] >> 7) + (bytes[2] & 0xFF) * 2\n + (bytes[3] & 0x0F) * 512);\n decoded.gpsSuccesses = 32 * ((bytes[3] >> 4) + (bytes[4] & 0x3F) * 16);\n decoded.gpsFails = 32 * ((bytes[4] >> 6) + (bytes[5] & 0x3F) * 4);\n decoded.aveGpsFixS = 1 * ((bytes[5] >> 6) + (bytes[6] & 0x7F) * 4);\n decoded.aveGpsFailS = 1 * ((bytes[6] >> 7) + (bytes[7] & 0xFF) * 2);\n decoded.aveGpsFreshenS = 1 * ((bytes[7] >> 8) + (bytes[8] & 0xFF) * 1);\n decoded.wakeupsPerTrip = 1 * ((bytes[8] >> 8) + (bytes[9] & 0x7F) * 1);\n decoded.uptimeWeeks = 1 * ((bytes[9] >> 7) + (bytes[10] & 0xFF) * 2);\n }\n\n return decoded;\n}","finalize":"","libs":[],"x":370,"y":200,"wires":[["7aede05c.a9783"]]},{"id":"333f342c.ef334c","type":"inject","z":"1f9de5c0.4c944a","name":"","props":[{"p":"payload"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"{\"payload_raw\":\"1Ok77vxxVxIUAKE=\",\"port\":1,\"app_id:\":\"ttn_tracker_oyster_123\",\"dev_id\":\"oyster_2\",\"hardware_serial\":\"70B3D57050006F77\",\"counter\":47}","payloadType":"json","x":190,"y":200,"wires":[["67c0cd0e.e13064","60572671.a878e8"]]},{"id":"7aede05c.a9783","type":"debug","z":"1f9de5c0.4c944a","name":"Decoder 1","active":true,"tosidebar":true,"console":false,"tostatus":true,"complete":"true","targetType":"full","statusVal":"payload","statusType":"auto","x":630,"y":200,"wires":[]},{"id":"60572671.a878e8","type":"function","z":"1f9de5c0.4c944a","name":"Decoder 2","func":"let data = msg.payload.payload_raw;\nlet bytes = new Buffer(data,'Base64');\n\nlet decoded = context.Decoder(bytes, msg.payload.port);\nmsg.payload.decoded_payload = decoded;\nreturn msg;","outputs":1,"noerr":0,"initialize":"context.Decoder = function(bytes, port) {\n // Decode an uplink message from a buffer\n // (array) of bytes to an object of fields.\n var decoded = {};\n\n if (port === 1)\n {\n decoded.type = \"position\";\n \n decoded.latitudeDeg = bytes[0] + bytes[1] * 256 + bytes[2] * 65536 + bytes[3] * 16777216;\n if (decoded.latitudeDeg >= 0x80000000)\n decoded.latitudeDeg -= 0x100000000;\n decoded.latitudeDeg /= 1e7;\n \n decoded.longitudeDeg = bytes[4] + bytes[5] * 256 + bytes[6] * 65536 + bytes[7] * 16777216;\n if (decoded.longitudeDeg >= 0x80000000)\n decoded.longitudeDeg -= 0x100000000;\n decoded.longitudeDeg /= 1e7;\n \n decoded.inTrip = ((bytes[8] & 0x1) !== 0) ? true : false;\n decoded.fixFailed = ((bytes[8] & 0x2) !== 0) ? true : false;\n decoded.headingDeg = (bytes[8] >> 2) * 5.625;\n \n decoded.speedKmph = bytes[9];\n decoded.batV = bytes[10] * 0.025;\n }\n else if (port === 2)\n {\n decoded.type = \"downlink ack\";\n \n decoded.sequence = (bytes[0] & 0x7F);\n decoded.accepted = ((bytes[0] & 0x80) !== 0) ? true : false;\n decoded.fwMaj = bytes[1];\n decoded.fwMin = bytes[2];\n }\n else if (port === 3)\n {\n decoded.type = \"stats\";\n \n decoded.initialBatV = (((bytes[0] & 0xF) !== 0) ? (4.0 + (bytes[0] & 0xF) * 0.100) : null);\n decoded.txCount = 32 * ((bytes[0] >> 4) + (bytes[1] & 0x7F) * 16);\n decoded.tripCount = 32 * ((bytes[1] >> 7) + (bytes[2] & 0xFF) * 2\n + (bytes[3] & 0x0F) * 512);\n decoded.gpsSuccesses = 32 * ((bytes[3] >> 4) + (bytes[4] & 0x3F) * 16);\n decoded.gpsFails = 32 * ((bytes[4] >> 6) + (bytes[5] & 0x3F) * 4);\n decoded.aveGpsFixS = 1 * ((bytes[5] >> 6) + (bytes[6] & 0x7F) * 4);\n decoded.aveGpsFailS = 1 * ((bytes[6] >> 7) + (bytes[7] & 0xFF) * 2);\n decoded.aveGpsFreshenS = 1 * ((bytes[7] >> 8) + (bytes[8] & 0xFF) * 1);\n decoded.wakeupsPerTrip = 1 * ((bytes[8] >> 8) + (bytes[9] & 0x7F) * 1);\n decoded.uptimeWeeks = 1 * ((bytes[9] >> 7) + (bytes[10] & 0xFF) * 2);\n }\n\n return decoded;\n}","finalize":"","libs":[],"x":370,"y":260,"wires":[["7fc1a132.7f07e"]]},{"id":"7fc1a132.7f07e","type":"debug","z":"1f9de5c0.4c944a","name":"Decoder 2","active":true,"tosidebar":true,"console":false,"tostatus":true,"complete":"true","targetType":"full","statusVal":"payload","statusType":"auto","x":610,"y":260,"wires":[]}]
```
---
### Author:  [@Steve-Mcl](https://discourse.nodered.org/u/Steve-Mcl)
#### Post date: [14 July 2021 14:53 UTC](https://discourse.nodered.org/t/setting-json-structure/48409/7 "2021-07-14T14:53:01Z")
As I said above, the problem is
> [@Steve-Mcl](#):
>
> msg.payload.uplink\_message.decoded\_payload = decoded;
Change Decoder 1 to ...
```auto
let data = msg.payload.payload_raw;
let bytes = new Buffer(data,'Base64');
let decoded = context.Decoder(bytes, msg.payload.port);
msg.payload.uplink_message = { decoded_payload: decoded };
return msg;
```
you will get...
---
### Author:  [@ScheepersJohan](https://discourse.nodered.org/u/ScheepersJohan)
#### Post date: [14 July 2021 15:06 UTC](https://discourse.nodered.org/t/setting-json-structure/48409/8 "2021-07-14T15:06:13Z")
Thank you @Steve-Mcl
So you first need to make uplink\_message an property of payload. Then you can add the property decoded\_payload to uplink\_message.
```auto
let bytes = Buffer.from(msg.payload.payload_raw,'Base64');
let decoded = context.Decoder(bytes, msg.payload.port);
msg.payload.uplink_message = { decoded_payload: decoded };
return msg;
```
---
### Author:  [@system](https://discourse.nodered.org/u/system)
#### Post date: [28 July 2021 15:06 UTC](https://discourse.nodered.org/t/setting-json-structure/48409/9 "2021-07-28T15:06:21Z")
This topic was automatically closed 14 days after the last reply. New replies are no longer allowed.