ESP8266 SPIFFS not saving correctly?

Question

Hey all I am having some issues with the SPIFFS for this Wemos D1 mini ESP8266 controller.

This is my Arduino sketch:

#include <FS.h>
#include <ArduinoJson.h>
struct RGBLA {
 uint8_t R;
 uint8_t G;
 uint8_t B;
 uint8_t L;
 uint8_t A;
};
void setup() {
 if (!SPIFFS.begin()) {
 Serial.println("error while mounting filesystem!");
 } else { 
 // put your setup code here, to run once:
 RGBLA returnedVars = readSPIFFS();
 Serial.begin(115200);
 Serial.println();
 Serial.println("Starting...");
 Serial.println("readSPIFFS 1");
 Serial.print("R: ");
 Serial.println(returnedVars.R);
 Serial.print("G: ");
 Serial.println(returnedVars.G);
 Serial.print("B: ");
 Serial.println(returnedVars.B);
 Serial.print("L: ");
 Serial.println(returnedVars.L);
 Serial.print("AmbientLight: ");
 Serial.println(returnedVars.A);
 Serial.println("==================================");
 returnedVars = saveToSPIFFS(25,77, 107, 250, 155, false); 
 Serial.println("saveToSPIFFS #1");
 Serial.print("R: ");
 Serial.println(returnedVars.R);
 Serial.print("G: ");
 Serial.println(returnedVars.G);
 Serial.print("B: ");
 Serial.println(returnedVars.B);
 Serial.print("L: ");
 Serial.println(returnedVars.L);
 Serial.print("AmbientLight: ");
 Serial.println(returnedVars.A);
 Serial.println("==================================");
 returnedVars = saveToSPIFFS(205,17, 68, 50, 15, true);
 Serial.println("saveToSPIFFS #2");
 Serial.print("R: ");
 Serial.println(returnedVars.R);
 Serial.print("G: ");
 Serial.println(returnedVars.G);
 Serial.print("B: ");
 Serial.println(returnedVars.B);
 Serial.print("L: ");
 Serial.println(returnedVars.L);
 Serial.print("AmbientLight: ");
 Serial.println(returnedVars.A);
 returnedVars = readSPIFFS();
 Serial.println("readSPIFFS 2");
 Serial.print("R: ");
 Serial.println(returnedVars.R);
 Serial.print("G: ");
 Serial.println(returnedVars.G);
 Serial.print("B: ");
 Serial.println(returnedVars.B);
 Serial.print("L: ");
 Serial.println(returnedVars.L);
 Serial.print("AmbientLight: ");
 Serial.println(returnedVars.A);
 Serial.println();
 Serial.println("END!");
 }
}
void loop() {
 // put your main code here, to run repeatedly:
}
RGBLA saveToSPIFFS(uint8_t R, uint8_t G, uint8_t B, uint8_t L, uint8_t A, bool saveA) {
 File configFile = SPIFFS.open("/config.json", "w+");
 if (configFile.size() > 3072) {
 Serial.println("Config file size is too large.");
 } else {
 Serial.print("Writing json to Config file...");
 StaticJsonBuffer<200> jsonBuffer;
 JsonObject& json = jsonBuffer.createObject();
 //Get the old value and save it
 RGBLA returnedVars = readSPIFFS();
 Serial.println("Old Values?");
 Serial.print("R: ");
 Serial.println(returnedVars.R);
 Serial.print("G: ");
 Serial.println(returnedVars.G);
 Serial.print("B: ");
 Serial.println(returnedVars.B);
 Serial.print("L: ");
 Serial.println(returnedVars.L);
 Serial.print("AmbientLight: ");
 Serial.println(returnedVars.A);
 if (saveA) {
 //Save Ambient Light data
 json["R"] = returnedVars.R;
 json["G"] = returnedVars.G;
 json["B"] = returnedVars.B;
 json["L"] = returnedVars.L;
 json["A"] = A;
 //Now save the new data
 returnedVars.A = A;
 } else {
 //Save RGBL data
 json["R"] = R;
 json["G"] = G;
 json["B"] = B;
 json["L"] = L; 
 json["A"] = returnedVars.A;
 //Now save the new data
 returnedVars.R = R;
 returnedVars.G = G;
 returnedVars.B = B;
 returnedVars.L = L;
 }
 json.printTo(configFile);
 configFile.close();
 //Read new saved values into struct
 //returnedVars = readSPIFFS();
 return returnedVars;
 }
}
RGBLA readSPIFFS() {
 bool exist = SPIFFS.exists("/config.json");
 if (exist) {
 Serial.println("YAY!");
 } else {
 Serial.println("Boo!");
 }
 File configFile = SPIFFS.open("/config.json", "r");
 std::unique_ptr<char[]> buf(new char[configFile.size()]);
 configFile.readBytes(buf.get(), configFile.size());
 DynamicJsonBuffer jsonBuffer;
 JsonObject& json = jsonBuffer.parseObject(buf.get()); 
 RGBLA returnedVars;
 String debugLogData;
 json.printTo(debugLogData);
 Serial.println("===============");
 Serial.println(debugLogData);
 Serial.println("===============");
 returnedVars.R = json["R"];
 returnedVars.G = json["G"];
 returnedVars.B = json["B"];
 returnedVars.L = json["L"];
 returnedVars.A = json["A"];
 configFile.close();
 return returnedVars;
}

And this is the console output:

Starting...
readSPIFFS 1
R: 0
G: 0
B: 0
L: 0
AmbientLight: 25
==================================
Writing json to Config file...YAY!
===============
{}
===============
Old Values?
R: 0
G: 0
B: 0
L: 0
AmbientLight: 0
saveToSPIFFS #1
R: 25
G: 77
B: 107
L: 250
AmbientLight: 0
==================================
Writing json to Config file...YAY!
===============
{}
===============
Old Values?
R: 0
G: 0
B: 0
L: 0
AmbientLight: 0
saveToSPIFFS #2
R: 0
G: 0
B: 0
L: 0
AmbientLight: 25
YAY!
===============
{"R":0,"G":0,"B":0,"L":0,"A":25}
===============
readSPIFFS 2
R: 0
G: 0
B: 0
L: 0
AmbientLight: 25
END!

As you can see, the first old values has all 0's which is incorrect. AmbientLight should be 25 at that point since readSPIFFS 1 has 25. So this should read:

Old Values?
R: 0
G: 0
B: 0
L: 0
AmbientLight: 25

saveToSPIFFS #1 is sending values 25, 77, 107, 250, 155 and false which then outputs correctly as:

R: 25
G: 77
B: 107
L: 250
AmbientLight: 0

But this time AmbientLight should still be 25 since it was sent false. It should have taken the old value (25) and placed it into the newer save.

R: 25
G: 77
B: 107
L: 250
AmbientLight: 25

Moving on to saveToSPIFFS #2 the values again are incorrect. The AmbientLight however is correct here. Instead of this output:

R: 0
G: 0
B: 0
L: 0
AmbientLight: 25

it should be gathering the 4 previous old values:

R: 25
G: 77
B: 107
L: 250
AmbientLight: 25

The json after this should not be this:

{"R":0,"G":0,"B":0,"L":0,"A":25}

It should be this:

{"R":250,"G":77,"B":107,"L":250,"A":25}

And lastly, the output of readSPIFFS 2:

R: 0
G: 0
B: 0
L: 0
AmbientLight: 25

Is incorrect. It should output:

R: 25
G: 77
B: 107
L: 250
AmbientLight: 25

Then after a reset it should have that and not the below for readSPIFFS 1:

R: 0
G: 0
B: 0
L: 0
AmbientLight: 25

So, where am I messing up here?

UPDATE

struct RGBLA {
 uint8_t R;
 uint8_t G;
 uint8_t B;
 uint8_t L;
 uint8_t A;
};
void setup() {
 RGBLA returnedValues = readSPIFFS();
 Serial.println("readSPIFFS 1");
 Serial.print("R: ");
 Serial.println(returnedVars.R);
 Serial.print("G: ");
 Serial.println(returnedVars.G);
 Serial.print("B: ");
 Serial.println(returnedVars.B);
 Serial.print("L: ");
 Serial.println(returnedVars.L);
 Serial.print("AmbientLight: ");
 Serial.println(returnedVars.A);
 returnedValues = saveToSPIFFS(205, 17, 68, 50, 15, false);
 Serial.println("saveToSPIFFS 1");
 Serial.print("R: ");
 Serial.println(returnedVars.R);
 Serial.print("G: ");
 Serial.println(returnedVars.G);
 Serial.print("B: ");
 Serial.println(returnedVars.B);
 Serial.print("L: ");
 Serial.println(returnedVars.L);
 Serial.print("AmbientLight: ");
 Serial.println(returnedVars.A);
}
RGBLA readSPIFFS() { 
 RGBLA returnedVars;
 File configFile = SPIFFS.open("/config.json", "r");
 if (configFile ) {
 Serial.println("YAY!");
 configFile.readBytes((byte*) &returnedValues, sizeof(RGBLA));
 configFile.close();
 } else {
 Serial.println("Boo!");
 }
 return returnedValues;
}
RGBLA saveToSPIFFS() { 
 File configFile = SPIFFS.open("/config.json", "w+");
 if (configFile.size() > 3072) {
 Serial.println("Config file size is too large.");
 } else {
 Serial.print("Writing to Config file...");
 //Get the old value and save it
 RGBLA returnedVars = readSPIFFS();
 Serial.println("Old Values:");
 Serial.print("R: ");
 Serial.println(returnedVars.R);
 Serial.print("G: ");
 Serial.println(returnedVars.G);
 Serial.print("B: ");
 Serial.println(returnedVars.B);
 Serial.print("L: ");
 Serial.println(returnedVars.L);
 Serial.print("AmbientLight: ");
 Serial.println(returnedVars.A);
 if (saveA) {
 //Save Ambient Light data
 returnedVars.A = A;
 } else {
 //Save RGBL data
 returnedVars.R = R;
 returnedVars.G = G;
 returnedVars.B = B;
 returnedVars.L = L;
 }
 configFile.write((byte*) &returnedVars, sizeof(RGBLA));
 configFile.close();
 return returnedVars;
}

• Juraj: why do you save it as JSON? simple file.write((byte*) rgbla, sizeof (RGBLA)) and file.read((byte*) rgbla, sizeof (RGBLA)) would work
• StealthRT: @Juraj can you put that as a potential answer and provide an example?
• Juraj: if it will be only one instance of the RGBLA struct and one file to save it, then create one global instance of the struct and rather return a succes state from functions

Answer 1

You can write a struct to file as binary data. This example is from my project.

global data:

struct Stats {
 int heatingTime; // minutes
 int consumedPower; // watts
};
Stats statsData;

snippet from setup():

 File file = SPIFFS.open(STATS_FILENAME, "r");
 if (file) {
 file.readBytes((byte*) &statsData, sizeof(statsData));
 file.close();
 }

snippet from statsSave() function:

 File file = SPIFFS.open(STATS_FILENAME, "w");
 if (file) {
 file.write((byte*) &statsData, sizeof(statsData));
 file.close();
 }

your updated readSPIFFS should be:

RGBLA readSPIFFS() {
 RGBLA returnedVars;
 File configFile = SPIFFS.open("/config.json", "r");
 if (configFile ) {
 Serial.println("YAY!");
 configFile.readBytes((byte*) &returnedValues, sizeof(RGBLA));
 configFile.close();
 } else {
 Serial.println("Boo!");
 }
 return returnedValues;
}

• StealthRT: So I can still return RGBLA like RGBLA returnedVars = readSPIFFS();?
• StealthRT: Check out my updated OP.
• Juraj: configFile.readBytes((byte*) &returnedValues, sizeof(returnedValues)); or configFile.readBytes((byte*) &returnedValues, sizeof(RGBLA));
• StealthRT: Alright corrected that in the update. Do I still need to use return returnedVars; or is it already populating the strut?
• Juraj: what is configFile["R"]?