DeserializationError of ESP32 SPIFFS json file returns error 'incompleteInput'

[400GreyBike]

I'm struggling to get a Json file in ESP32 SPIFFS to deserialize unless I create a buffer and read that. In the SD example it shows

File file = SD.open(filename);

and then calls

StaticJsonDocument<512> doc;
DeserializationError error = deserializeJson(doc, file);`

If I open my file using

File fileConfig = SPIFFS.open("/PM8Config.json", FILE_READ);

and then deserialize using

StaticJsonDocument<1000> doc;
DeserializationError error = deserializeJson(doc, fileConfig);

I get a failure indicating "IncompleteInput"

If however I use the following, I am able to deserialise successfully where String data is in the json, but I get no data where int data items are i.e. pollRate

File fileConfig = SPIFFS.open("/PM8Config.json", FILE_READ); // Check if we can open the Config file
if (!fileConfig) {
Serial.println("There was an error opening the Config file");
Serial2.print(F("pgInitConfig.t10.txt="Failed"));
//return false;
}else{
Serial.println("Config File was successfully opened");
Serial2.print(F("pgInitConfig.t10.txt="Opened"));
//return true;
size_t fileSize = fileConfig.size();
std::unique_ptr<char[]> buf(new char[fileSize]);
fileConfig.readBytes(buf.get(), fileSize);
StaticJsonDocument<1000> doc;
DeserializationError error = deserializeJson(doc, buf.get());
// Test if parsing succeeds.
if (error) {
Serial.print(F("deserializeJson() failed: "));
Serial.println(error.c_str());
//return;
}
int testJsonRead = doc["sensorData"]["pollRate"];
Serial.print("Test JSON Read variable (should read '30': " );
Serial.println(testJsonRead);
const char* testPW = doc["password"];
Serial.print("Test JSON Read variable (should show PW: " );
Serial.println(testPW); `

The json file in SPIFFS is (and I can Serial.print this without an issue):

{
"platform": "NodeMCU32s",
"framework": "Arduino",
"version": "0.1a",
"vdated": "30/12/19",
"ssid": "myssid",
"password": "mypassword",
"thingSpeakInfo":{
"thingspeakAddress": "api.thingspeak.com",
"thingspeakChannelID": 000000,
"thingspeakReadApiKey": "myAPIKey",
"thingspeakWriteApiKey": "myAPIKey"
},
"checkWxApiKey": "myAPIKey",
"sensorData":{
"pollRate": 30,
"stuff": "stuff"
}
}

I'm clearly missing something here but can't figure out why I can't simply call the fileConfig object without having to use buf.get()?

Any help would be appreciated and I think it's time to buy the book :-)

[400GreyBike]

Having found another thread, it needs the removal of the readBytes() statement to ensure the pointer isn't at the end of the file.

Apologies for adding a somewhat wasted "issue" to an excellent library.

[bblanchon]

No worries @400GreyBike.
Thank you for using ArduinoJson.