Исходники и презентации

lessons/contexts/context_with_http_server/main.go

@@ -0,0 +1,34 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+)
+
+func main() {
+	helloWorldHandler := http.HandlerFunc(handle)
+	http.Handle("/welcome", injectTraceID(helloWorldHandler))
+	_ = http.ListenAndServe(":8080", nil)
+}
+
+func handle(_ http.ResponseWriter, r *http.Request) {
+	value, ok := r.Context().Value("trace_id").(string)
+	if ok {
+		fmt.Println(value)
+	}
+
+	makeRequest(r.Context())
+}
+
+func makeRequest(_ context.Context) {
+	// requesting to database with context
+}
+
+func injectTraceID(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		ctx := context.WithValue(r.Context(), "trace_id", "12-21-33")
+		req := r.WithContext(ctx)
+		next.ServeHTTP(w, req)
+	})
+}