Using default value problem (x=json["Test"] | x;)

[ttlappalainen]

I have problem with using default value. I have on json: "Test": 1

  const char *strTest;
  double v=5;
  v=jsonProperty[strTest] | v;

Works fine and returns 1, but

  uint8_t v=5;
  v=jsonProperty[strTest] | v;

returns 5 allways. Last works fine without | v

[bblanchon]

Hi @ttlappalainen,

I cannot reproduce the bug.
See demo: https://wandbox.org/permlink/Q0FLElI8oJ9nuThD

Please provide an MCVE.

Regards,
Benoit

[ttlappalainen]

Now I am not sure is this bug or feature. With below code first returns wrong and second right. Also I expect that the reason is that you when I am using existing data, it has internally double object.

#include <Arduino.h>
#include <ArduinoJson.h>

void setup() {
  Serial.begin(115200);
  delay(300);

  Serial.println("Startup");

  DynamicJsonBuffer jsonBuffer(1000);
  jsonBuffer.clear();
  JsonObject& jsonControl=jsonBuffer.createObject();
  double a=100;
  jsonControl["Test"]=a;

  jsonControl.prettyPrintTo(Serial);

  uint8_t v=jsonControl["Test"] | 5;
  
  Serial.println();
  Serial.print("Read value:"); Serial.println(v);

  char buf[1000];
  jsonControl.prettyPrintTo(buf,1000);
  DynamicJsonBuffer jsonBuffer2(1000);
  JsonObject& jsonControl2=jsonBuffer2.parseObject(buf);
  v=jsonControl2["Test"] | v;
  Serial.println();
  Serial.print("Read value:"); Serial.println(v);
}

void loop() {
}

[bblanchon]

DynamicJsonBuffer jsonBuffer(1000);
char buf[1000];
DynamicJsonBuffer jsonBuffer2(1000);

Are you sure that there is enough RAM on your micro-controller?

[ttlappalainen]

Teensy 3.5 RAM 196 kB. Totally with flash more than on my first computer:)

[bblanchon]

OK, now I see it.

jsonControl["Test"] is a double so when you try to extract a uint8_t, it returns the default value.

To me, it's a bug because it's not consistent with:

uint8_t v = jsonControl2["Test"]; // return 100 as expected

[ttlappalainen]

OK - thanks. Meanwhile I can go around problem with
jsonControl["Test"]=(uint8_t)a;
where it is possible.