El Bruno

Hi !

In today’s post I’ll share an scenario about:

Invoke an Azure Function to get JSON data, and Parse the JSON data

Yesterday I wrote on how to invoke an Azure Function and get JSON data for my Digital Twin scenario. The response from the function is similar to this one:

{
    "state": 0,
    "desc": "closed",
    "source": "blog"
}

There are several libraries to work with JSON in the Arduino ecosystem, I’m using this one and so far, so good.

GitHub – Arduino_JSON

The code is super easy to read

• Include Arduino_JSON.h in the include section
• Parse the string with the Azure Function response, this creates a JSONVar object
• Validate for a valid JSON object
• Validate JSON properties to get state, description and source

// Include section
#include <Arduino_JSON.h>

// Azure Function and Door Information
int    state = -1;
String state_desc = "undefined";
String state_source = "undefined";

void getDoorStateInformation(String response){
  // init default values
  state = -1;
  state_desc = "undefined";
  state_source = "undefined";  

  // process JSon Response
  JSONVar myObject = JSON.parse(response);
  
  if (JSON.typeof(myObject) == "undefined") {
    Serial.println("Parsing input failed!");
    return;
  }
  
  if (myObject.hasOwnProperty("state")) {
    state = (int)myObject["state"];
  }
  if (myObject.hasOwnProperty("desc")) {
    state_desc = myObject["desc"];
  }
  if (myObject.hasOwnProperty("source")) {
    state_source = myObject["source"];
  }
  
  Serial.print("state: ");
  Serial.print(state);
  Serial.print(" - desc: ");
  Serial.print(state_desc);
  Serial.print(" - source: ");
  Serial.println(state_source); 
}

I’m close to finish the Wio Terminal application. Next step, let’s interact with the Digital Twin using the Wio Terminal buttons.

References

• Download Arduino IDE
• Wiki Seeed – Historgram
• Wiki Seeed – loading Images
• Wiki Seeed – Installing the File System Library
• Wiki Seed – Wifi Connectivity
• GitHub – Arduino_JSON

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