Hi,

I have a issue reading (or writing) a nested JSON on an ESP8266.
What I try to have is a file is [ {"m":1, "h":2} , {"m":10, "h":20} , {"m":100, "h":200} ]

I am using SPIFFS to write the JSON to a file then to read it.

For one object is working fine, but for nested array does not working at all.

Code below:

Not working case:

#include <ESP8266WiFi.h>
#include <ESP8266WebServer.h>
#include <ArduinoJson.h>
#include "FS.h"

void setup() {
// put your setup code here, to run once:
Serial.begin(115200);
delay(2000);
int i=0;
if( SPIFFS.begin() )
{
File my_file = SPIFFS.open("xfile.json", "w");
if (!my_file) {
Serial.println("failed to open xfile.json file for writing :-(");
return; //==============>
}
StaticJsonBuffer<300> jsonBuffer;
JsonArray& my_array = jsonBuffer.createArray();
for(i=0;i<3;i++)
{
JsonObject& my_entry = my_array.createNestedObject();
my_entry["m"] = 20;
my_entry["h"] = 14;
}
my_array.printTo(Serial);
Serial.println("");
my_array.printTo(my_file);
my_file.close();
delay(1000);
//---------------------------- READ ----------------------------------
File myFile = SPIFFS.open("xfile.json", "r");
if (myFile)
{
Serial.println("opened xfile.json file");
size_t size = myFile.size();
// Allocate a buffer to store contents of the file.
std::unique_ptr<char[]> buf(new char[size]);
Serial.println(size);
Serial.println(buf.get());
myFile.readBytes(buf.get(), size);
DynamicJsonBuffer jsonBuffer;
//StaticJsonBuffer<200> jsonBuffer;
JsonObject& jsona = jsonBuffer.parseObject(buf.get());
jsona.printTo(Serial);
Serial.println("");
if (jsona.success())
{
Serial.println("READ OK");
}
else
{
Serial.println("Json invalid");
}
}
myFile.close();
}//end SPIFFS.begin
}//end setup
void loop() {
// put your main code here, to run repeatedly:
}

and working case:

#include <ESP8266WiFi.h>
#include <ESP8266WebServer.h>
#include <ArduinoJson.h>
#include "FS.h"

void setup() {
// put your setup code here, to run once:
Serial.begin(115200);
delay(2000);
int i=0;
if( SPIFFS.begin() )
{
File my_file = SPIFFS.open("xfile.json", "w");
if (!my_file) {
Serial.println("failed to open xfile.json file for writing :-(");
return; //==============>
}

StaticJsonBuffer<300> jsonBuffer;
JsonObject& my_entry = jsonBuffer.createObject();
my_entry["m"] = 20;
my_entry["h"] = 14;

my_entry.printTo(Serial); 
Serial.println("");
my_entry.printTo(my_file);
my_file.close();

delay(1000);
//---------------------------- READ ----------------------------------

File myFile = SPIFFS.open("xfile.json", "r");
if (myFile) 
{
    Serial.println("opened xfile.json file");
    size_t size = myFile.size();
    // Allocate a buffer to store contents of the file.
    std::unique_ptr<char[]> buf(new char[size]);
    Serial.println(size);
    Serial.println(buf.get());
    myFile.readBytes(buf.get(), size);
    DynamicJsonBuffer jsonBuffer;
    //StaticJsonBuffer<200> jsonBuffer;        
    JsonObject& jsona = jsonBuffer.parseObject(buf.get());
    jsona.printTo(Serial);
    Serial.println("");
    if (jsona.success()) 
    { 
      Serial.println("READ OK");
    }
    else
    {
      Serial.println("Json invalid");
    }
}
myFile.close();

}//end SPIFFS.begin
}//end setup

void loop() {
// put your main code here, to run repeatedly:

}