MQTT-in node - autodetect string, buffer and JSON object

Core Development Feature Requests
1

I am changing a lot of stuff in my flows and had to distinguish strings from objects coming from mqtt-in.

The "auto-detect (string or buffer)" does not capture JSON.

Looking in the code, the else formats it as a string. Could this be changed to trying to parse it as json first (try/catch) catch would parse it as string:

  if (isUtf8(payload)) { 
                    try { payload = JSON.parse(payload); }
                    catch { payload = payload.toString(); }
                }

source location

Just changed it in my running instance, works quite nicely. Although it would be nice to remove the option from the pulldown menu, it would have a lot of implications for existing flows. But the auto-detect/parse of/to json is quite helpful.

I am sure I am not capturing all the exceptions, but I want to eliminate the manual capturing/parsing.

2

The reason it won't be done is exactly because "it would have a lot of implications for existing flows..." as in, it would break a lot of flows.

3

My test is not the test to use.

I am talking about the autodetect feature, it should be possible to test whether or not the data is a string, buffer or a json object and if it is the latter send it as a json object. It is a bit redundant to use:

mqtt-in -> json node
in auto-detect mode.

It is an improvement, sometimes you have to break stuff to move forward.

4

I don't fully understand what you mean here, I thought the data from mqtt could only be a buffer or a string. What do you mean by a json object. By definition JSON is a string.

5

You are correct with the terminology; I mean a string formatted as an javascript object.

string vs object. The string is not useful and could be converted automagically.

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Screenshot 2019-08-09 at 13.36.30.jpg588Ă—824 86.5 KB

6

If the improvement breaks people then it's not much of an improvement. The option is there to output a parsed JSON object if you want.

1 Like
7

The option is there to output a parsed JSON object if you want.

That is correct, except that I have to use multiple mqtt nodes and filter/convert its output first.
I have reduced the number of mqtt nodes from 20+ to 1, I see it as an improvement.

8

Possibly a solution would be to add an option to the dropdown list "Autodetect JSON or string" (or something similar) which attempts to parse a string and returns the object if successful, otherwise returns the string as is.

9

Wow, I know that IoT is where digital meets physical but I didn't know that Node-RED had already progressed to the ability to break people!!

:skull_and_crossbones:

We certainly don't want that :wink:

10

I think this forum is littered with the remains of those irreparably damaged by node-red.

2 Likes
11

I'm sure you know IT folk who have rolled out a "simple update" on a Friday afternoon, and then had to spend the weekend undoing the mayhem.

2 Likes
12

Urm, no, never :cough: :blush:

3 Likes
13

I was gonna suggest exactly this but decided to wait it out ...

14

If I may jump in here I have a terribly naive question. I have a bunch of Sonoff switches running just fine, have their status on Dashboard, etc....

What I cannot figure out is how to parse data received from a Sonoff TH10 (tasmota) device to extract variable data (like temp and humidity). I have looked around and if I've seen it explained, I didn't know it. Here is an example response:

Beechnut/Sauna-TH10/stat/STATUS10 : msg : Object
object
topic: "Beechnut/Sauna-TH10/stat/STATUS10"
payload: "{"StatusSNS":{"Time":"2019-11-28T16:11:11","SI7021":{"Temperature":22.3,"Humidity":45.5},"TempUnit":"C"}}"
qos: 0
retain: false
_msgid: "57bab8b7.eff8a8"

I actually can get it to work (if the MQTT respons ehas the proper data) by using

    temperature = msg.payload.StatusSNS.SI7021.Temperature;
    humidity = msg.payload.StatusSNS.SI7021.Humidity;

however there are a bunch of MQTT messages that cause the error msg in debug of:

function : (error)
"TypeError: Cannot read property 'SI7021' of undefined"

that I can't seem to stop occurring. There has to be a better method, I just don't know what it is.
st

15

This is not the right topic, open a new one with your question.