# Get value from MQTT and set a variable **URL:** \ **Category:** Questions & Help\ **Created:** [December 30, 2018, 12:01pm UTC](https://community.homey.app/t/get-value-from-mqtt-and-set-a-variable/6090 "2018-12-30T12:01:31Z")\ **Posts on this page:** 10\ **Page:** 3
**Author:** ![Peter\_Kawa](https://sea1.discourse-cdn.com/flex025/user_avatar/community.homey.app/peter_kawa/32/173848_2.png) [@Peter\_Kawa](https://community.homey.app/u/Peter_Kawa)\ **Post date:** [February 23, 2022, 12:26am UTC](https://community.homey.app/t/get-value-from-mqtt-and-set-a-variable/6090/41 "2022-02-23T00:26:07Z")
Here’s a way to do this (hit the `v` icon on the right to view the flow) > [@MQTT NodeRed values](https://community.homey.app/t/mqtt-nodered-values/60459/6): > > You’re welcome. Yea, I left it for you to figure out grimacing It is possible, but is it better… There’s a disadvantage: As you can see, there’s a delay needed. While the shortest delay possible is ONE whole second, using 2 flows makes it respond quicker. In the previous 2 flow example, the 2nd flow fires as soon as the numeric var has changed… ---
**Author:** ![sebyldino](https://sea1.discourse-cdn.com/flex025/user_avatar/community.homey.app/sebyldino/32/20067_2.png) [@sebyldino](https://community.homey.app/u/sebyldino)\ **Post date:** [February 23, 2022, 5:48am UTC](https://community.homey.app/t/get-value-from-mqtt-and-set-a-variable/6090/42 "2022-02-23T05:48:29Z")
Hello, Thank you for your answer. But it does not work. I edit my post below with add the MQTT topic. I have “home/esp32/BTtoMQTT/DA9A435CDCB9” not “home/esp32/BTtoMQTT/DA9A435CDCB9/rssi” I think MQTT message is string value, the Virtual Device use string too. ---
**Author:** ![robertklep](https://sea1.discourse-cdn.com/flex025/user_avatar/community.homey.app/robertklep/32/160628_2.png) [@robertklep](https://community.homey.app/u/robertklep)\ **Post date:** [February 23, 2022, 6:21am UTC](https://community.homey.app/t/get-value-from-mqtt-and-set-a-variable/6090/43 "2022-02-23T06:21:31Z")
> [@sebyldino](#): > > i tried some script in this topic but does not work. Using a script is the only way, though (I don’t think there are apps that can extract properties from JSON data). Something like this: ```auto const message = JSON.parse(args[0]); await tag('rssi', Number(message.rssi)); ``` And pass the received message from the MQTT broker, as a token, to the script: WHEN trigger when message is received on topic `home/esp32/BTtoMQTT/DA9A435CDCB9` AND execute `script` with argument `[message]` THEN … ---
**Author:** ![sebyldino](https://sea1.discourse-cdn.com/flex025/user_avatar/community.homey.app/sebyldino/32/20067_2.png) [@sebyldino](https://community.homey.app/u/sebyldino)\ **Post date:** [February 23, 2022, 6:50am UTC](https://community.homey.app/t/get-value-from-mqtt-and-set-a-variable/6090/44 "2022-02-23T06:50:30Z")
With this scipt: ```auto const message = JSON.parse(args[0]); await tag('rssi', Number(message.rssi)); ``` I get this error: ```auto ——————————————————— ❌ Script Error ⚠️ SyntaxError: Unexpected token u in JSON at position 0 at JSON.parse () at StringToNumber.js:1:22 at processTicksAndRejections (internal/process/task_queues.js:97:5) ``` “message” must be “home/esp32/BTtoMQTT/DA9A435CDCB9”? Edit: I think i found thomething. I get an error because u is undefined (args is undefined in the script, but it will be in the flow). I wil try… ---
**Author:** ![robertklep](https://sea1.discourse-cdn.com/flex025/user_avatar/community.homey.app/robertklep/32/160628_2.png) [@robertklep](https://community.homey.app/u/robertklep)\ **Post date:** [February 23, 2022, 7:02am UTC](https://community.homey.app/t/get-value-from-mqtt-and-set-a-variable/6090/45 "2022-02-23T07:02:29Z")
> [@sebyldino](#): > > “message” must be “home/esp32/BTtoMQTT/DA9A435CDCB9”? No, it must be a flow token representing the message. ---
**Author:** ![sebyldino](https://sea1.discourse-cdn.com/flex025/user_avatar/community.homey.app/sebyldino/32/20067_2.png) [@sebyldino](https://community.homey.app/u/sebyldino)\ **Post date:** [February 23, 2022, 8:01am UTC](https://community.homey.app/t/get-value-from-mqtt-and-set-a-variable/6090/46 "2022-02-23T08:01:44Z")
This is working: ```auto const message = JSON.parse('{"id":"D6:9A:43:5C:DC:B9","mac_type":1,"rssi":-54,"servicedata":"02008c411805b8dc7ea9"}'); console.log(message.rssi) return true; ``` ```auto -84 ——————————————————— ✅ Script Success ↩️ Returned: true ``` But not in the flow. I have tried to log something: [https://homey.app/f/QTOCBY/](https://homey.app/f/QTOCBY/) But nothing appear in the log. it looks like i’m not getting the messages. i have tried too with “home/#” in topic case of the first card but not working … ---
**Author:** ![robertklep](https://sea1.discourse-cdn.com/flex025/user_avatar/community.homey.app/robertklep/32/160628_2.png) [@robertklep](https://community.homey.app/u/robertklep)\ **Post date:** [February 23, 2022, 8:08am UTC](https://community.homey.app/t/get-value-from-mqtt-and-set-a-variable/6090/47 "2022-02-23T08:08:30Z")
> [@sebyldino](#): > > it looks like i’m not getting the messages. That seems to be the case, yes, so you should start by fixing that 😉 ---
**Author:** ![sebyldino](https://sea1.discourse-cdn.com/flex025/user_avatar/community.homey.app/sebyldino/32/20067_2.png) [@sebyldino](https://community.homey.app/u/sebyldino)\ **Post date:** [February 23, 2022, 8:10am UTC](https://community.homey.app/t/get-value-from-mqtt-and-set-a-variable/6090/48 "2022-02-23T08:10:17Z")
However, Home Assistant and Homey have been communicating perfectly for 2 years… 🙄 And I get message in the log in MQTT Client app ![image](https://us1.discourse-cdn.com/flex025/uploads/athom/original/3X/b/6/b6da699cc6846d9dde12601879b995fb581129a3.png) I don’t unsterstand what’s happen ---
**Author:** ![sebyldino](https://sea1.discourse-cdn.com/flex025/user_avatar/community.homey.app/sebyldino/32/20067_2.png) [@sebyldino](https://community.homey.app/u/sebyldino)\ **Post date:** [February 23, 2022, 1:21pm UTC](https://community.homey.app/t/get-value-from-mqtt-and-set-a-variable/6090/49 "2022-02-23T13:21:54Z")
This is the solution: > [@robertklep](#): > > Using a script is the only way, though (I don’t think there are apps that can extract properties from JSON data). > > Something like this: > > ```auto > const message = JSON.parse(args[0]); > await tag('rssi', Number(message.rssi)); > > ``` > > And pass the received message from the MQTT broker, as a token, to the script: > WHEN trigger when message is received on topic `home/esp32/BTtoMQTT/DA9A435CDCB9` > AND execute `script` with argument `[message]` > THEN … So this Flow works: > **[Rssi | Homey](https://homey.app/en-us/flow/u93LCY/)** The “?” tag in the last card is the homeyscript’s tag. I dont know why it does not appear. The error what i did, was add tag “Message received from topic” in the first card. Thank you for helping! 😃 ---
**Author:** ![Martijn\_Hoogenbosch](https://sea1.discourse-cdn.com/flex025/user_avatar/community.homey.app/martijn_hoogenbosch/32/10647_2.png) [@Martijn\_Hoogenbosch](https://community.homey.app/u/Martijn_Hoogenbosch)\ **Post date:** [April 6, 2022, 7:40am UTC](https://community.homey.app/t/get-value-from-mqtt-and-set-a-variable/6090/50 "2022-04-06T07:40:27Z")
Based on the scripts above I managed to automate my blinds, with the removal of support for my solar power I had to switch to MQTT and now I can lower and rise the blinds based on the MQTT value. Thanks guys! [Previous page](https://community.homey.app/t/get-value-from-mqtt-and-set-a-variable/6090.md?page=2)