JSON Text Decode reverses key and value

MIT App Inventor Help
1

Hello everyone,
I receive from my ESP32 by Bluetooth a JSON Data of the form :

[{"id":1,"altiButeeH":14},{"id":2,"altiButeeB":87}]

image

Screenshot_20250117-144841
Screenshot_20250117-1448411080×1920 373 KB

The reception JSON Data is good: key "id" first, then sensor key second as in my Arduino code: "altiSun", "zenith"
On the other hand, once decoded by "CallWeb1.JsonTextDecode" it reclassified in the table all the keys in alphabetical order so I have an exchange of keys for keys not starting with "a": it put id first, then "parking" (and "zenith") second.
Screenshot_20250117-145049
Screenshot_20250117-1450491080×1920 130 KB

in the ListView1 it display the index of position 1 which does not give me the expected keys.
How to force "CallWeb1.JsonTextDecode" to decode in the order of the keys / values ​​received?

I would like to avoid adding extensions to keep the code easy to understand because ...
P.S I am a beginner in Mit app, I learn quickly but you have to explain to me for a long time lol
Cheers
Chris

2

Please post your ESP32 code too.

It's hard to determine the logical structure of your data from the overly short data stream sample.

3

here it is:

String message = "memoires:["
               "{\"id\":1,\"altiButeeH\":" + String(altiButeeH) + "},"
               "{\"id\":2,\"altiButeeB\":" + String(altiButeeB) + "},"
               "{\"id\":3,\"aziButeeO\":" + String(aziButeeO) + "},"
               "{\"id\":4,\"aziButeeE\":" + String(aziButeeE) + "},"
               "{\"id\":5,\"aziOffset\":" + String(aziOffset) + "},"
               "{\"id\":6,\"altiOffset\":" + String(altiOffset) + "},"
               "{\"id\":7,\"aziPanelFloat\":" + String(aziPanelFloat) + "},"
               "{\"id\":8,\"altiPanelFloat\":" + String(altiPanelFloat) + "},"
               "{\"id\":9,\"altiSun\":" + String(altiSun) + "},"
               "{\"id\":10,\"altiPanel\":" + String(altiPanel) + "},"
               "{\"id\":11,\"aziSun\":" + String(aziSun) + "},"
               "{\"id\":12,\"aziPanel\":" + String(aziPanel) + "},"
               "{\"id\":13,\"aziVitesseSlide\":" + String(aziVitesseSlide) + "},"
               "{\"id\":14,\"altiVitesseSlide\":" + String(altiVitesseSlide) + "},"
               "{\"id\":15,\"aziVitesse\":" + String(aziVitesse) + "},"
               "{\"id\":16,\"altiVitesse\":" + String(altiVitesse) + "},"
               "{\"id\":17,\"parkingPosi\":" + String(parkingPosi) + "},"
               "{\"id\":19,\"zenith\":" + String(zenith) + "}"
               "]";

      Serial.print("affMemoires ");
      Serial.println(message);
      sendBluetoothMessage(message);  //========> TX Bluetooth

And the sendBluetoothMessage function :

void sendBluetoothMessage(const String& message) {
   SerialBT.print(message);
   SerialBT.print('\n');  // Ajout d'une nouvelle ligne pour plus de clarté
}

to retrieve global value, I split the message at the first ":". I deduce the complete JSON message: [{"id":1,"altiButeeH":14},{"id":2,"altiButeeB":87}....] as seen in lab_jsonData.

4

What do you want to show in your listview ? The records are still in the same order (by id number) after decoding

5

Besides the ListView presentation, how do you want to accumulate the data?

  • List of lists (table) structure with prescribed column order from the 19 row IDs, with a header row?
  • List of dictionaries, each with 19 attributes?
6

look at the first object: {"id":1,"altiButeeH":10}
Translation => [["altiButeeH",10],["id":1]] because "a" is placed before "i"
1st index of the list => (altiButeeH 10). Perfect.

Iook at the last object: {"id":19,"zenith":25}
Translation => [["id",19],["zenith":25]] because "i" is placed before "z"
1st index of the list => (id 19) . Bad

It seems that the translation puts in first place in the Array , the first of the 2 objects in alphabetical order: alti..., azi..., id.
Imagine if I had an object {"key":1,"deviceWest":10}
Translate => [["deviceWest",10],["key":1]] because "d" is before "k"
1st index => (deviceWest 10)

7

Obviously the final step is to display a dynamic table whose number of lines varies with the payload:
image
But I wanted to keep it simple at the beginning to understand what I was doing and not stupidly copy/paste. :smile:
Once again without using extensions (if possible).

8

image
superNinja.aia (3.4 KB)

blocks
blocks717×1008 77.3 KB

This can order the ListView Elements by id number.

1 Like
9

Also, see here: