Can't find the right documentation... Reading receive messages

[Alain Mizreh]

Hello,
First of all, I would like to say thank you for MySensors.
It seems to be doing all the things I expected for a longtime, and I have been trying to do it all by myself before...

So, I am new to MySensors, not to Arduino / ESP8266, etc...

I have been able to make a Gateway & a Sensor talk together.
I have been able to connect to my io.adafruit.com MQTT server, as well...

I am using the "void receive(MyMessage &msg)" routine to read incoming messages from my Sensor (a DHT22 based one).

But I cannot figure out how to get the data from it !
The variable I use doesn't seem to be a String, and I am pretty sure I coud get something like : MyNode = MyMessage.NODE_ID... but I can't find the explanation of how to read incoming messages...

Hint : I am a hardware engineer from 1985, and I developed my programming skills very late...

Here is the bit of code I use :

void receive(MyMessage &msg)
{

  
  String MyMessage;
  int MsgLen = MyMessage.length();
  
  String Humid = MyMessage.substring(12, MsgLen);
  
  Serial.println(MsgLen);
  Serial.println (Humid);
  

}```

The result is that MsgLen (Length of MyMessage) = 0. So to me this is not a String... 

Thanks for your help, 

Regards,

Alain

[mfalkvidd]

@Alain-Mizreh welcome to the MySensors community!

msg is an object, which contains lots of stuff. msg.getString(char* buffer) is probably what you are looking for.

Information about the MyMessage object is available at https://www.mysensors.org/download/sensor_api_20#message-manipulation. You might need to scroll inside the "code" box though, the get functions might not fit on the screen.

[Alain Mizreh]

@mfalkvidd , Thanks for your reply !
Would there be some code example to illustrate ?
I am bad at manipulating variables, and I don't get it...
The link you gave me is very detailed, however, I don't understand what I should do with all the variables described... Create one local variable for every field ?

Thanks a lot,

Regards,

Alain

[mfalkvidd]

@Alain-Mizreh only create a variable for the data you are using. If you use a string, get a string.