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wickra/examples/go/fetch_btcusdt/main.go
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// Download real BTCUSDT hourly klines from the Binance REST API into a CSV that the
// other examples can consume. Requires network access (build-only in CI).
package main
import (
"bufio"
"encoding/json"
"fmt"
"io"
"log"
"net/http"
"os"
"path/filepath"
)
func main() {
const url = "https://api.binance.com/api/v3/klines?symbol=BTCUSDT&interval=1h&limit=500"
fmt.Printf("Fetching %s\n", url)
resp, err := http.Get(url)
if err != nil {
log.Fatalf("request: %v", err)
}
defer resp.Body.Close()
body, err := io.ReadAll(resp.Body)
if err != nil {
log.Fatalf("read body: %v", err)
}
// Binance kline array: [openTime, open, high, low, close, volume, ...].
var klines [][]any
if err := json.Unmarshal(body, &klines); err != nil {
log.Fatalf("parse json: %v", err)
}
dir := "data"
if err := os.MkdirAll(dir, 0o755); err != nil {
log.Fatalf("mkdir: %v", err)
}
path := filepath.Join(dir, "btcusdt_1h.csv")
file, err := os.Create(path)
if err != nil {
log.Fatalf("create: %v", err)
}
defer file.Close()
writer := bufio.NewWriter(file)
defer writer.Flush()
fmt.Fprintln(writer, "timestamp,open,high,low,close,volume")
count := 0
for _, k := range klines {
ts := int64(k[0].(float64))
fmt.Fprintf(writer, "%d,%s,%s,%s,%s,%s\n", ts, k[1], k[2], k[3], k[4], k[5])
count++
}
fmt.Printf("Wrote %d klines to %s\n", count, path)
}