ESP8266 Community Forum

- Wed Jan 16, 2019 3:49 pm #80099 Hi all,
I must download a json file (180kB) from a server and I must do its parser. I use an esp8266 with Arduino IDE using the HTTPClient.h library and its examples.
The instructions used are http.GET() and http.GetString(). The GET give me a result ok (=200) but the getString return a empty string. Why? Because the file it's big? There are a solutions?
Can you help me please?
Thank you.

- Fri Jan 18, 2019 3:22 am #80127 Somehow your failing code was magically erased from the forum, please post it again.

Assumption is the mother of all f*ckups. At least: that's what I'm assuming.

- Fri Jan 18, 2019 3:57 am #80130

Somehow your failing code was magically erased from the forum, please post it again.

He probably didn't post any code. It seems like he didn't realize that 180kB JSON doesn't fit to CPU which has totally 80kB RAM so .getString() method ends with OOM... Solution: chunked/streaming transfer and streaming JSON parser ...

- Fri Jan 18, 2019 4:26 am #80132

Somehow your failing code was magically erased from the forum, please post it again.

1° Test:
File f = SPIFFS.open("/f.xml", "w");
http.begin(Link);
httpCode = http.GET();
if ((httpCode==200)){
f.println(http.getString());
f.close();
f = SPIFFS.open("/f.json", "r");
if (!f) {
Serial.println("file open failed");
}
String s1=f.readString();
Result 1°Test: httpCode=200 ( OK) but the string s1 it's empty. If I download a small file the string s1 it's ok.

2° Test:
File f = SPIFFS.open("/f.json", "w");
// if (f) {
http.begin(Link);
httpCode = http.GET();
if (httpCode > 0) {
if (httpCode == HTTP_CODE_OK) {
unsigned long t=millis();
http.writeToStream(&f);
unsigned long tempo=millis()-t;
Serial.print("tempo impiegato=");Serial.println(tempo);
delay(50);
f.close();
f = SPIFFS.open("/f.json", "r");
String s;
for (int i=1; i<=11000; i++){
s=f.readStringUntil(',');
}
f.close();
}
}
http.end();
Result 2°Test: httpCode=200 ( OK) and I can read all.
So, I could use the 2° code and download the entire file but How Can I do the parse json file?