## Three Issues Fixed ✅
### 1. Backend hit on every keypress ❌
**Problem:**
- Type "Bandung" → 7 API calls (B, Ba, Ban, Band, Bandu, Bandun, Bandung)
- Expensive for live rate APIs (Rajaongkir, UPS)
- Poor UX with constant loading
**Solution - Debouncing:**
```ts
const [debouncedCity, setDebouncedCity] = useState(city);
useEffect(() => {
const timer = setTimeout(() => {
setDebouncedCity(city);
}, 500); // Wait 500ms after user stops typing
return () => clearTimeout(timer);
}, [city]);
// Use debouncedCity in query key
queryKey: [..., debouncedCity]
```
**Result:**
- Type "Bandung" → Wait 500ms → 1 API call ✅
- Much better UX and performance
---
### 2. Same rates for different provinces ❌
**Problem:**
- Select "Jawa Barat" → JNE REG Rp31,000
- Select "Bali" → JNE REG Rp31,000 (wrong!)
- Should be different rates
**Root Cause:**
```ts
staleTime: 5 * 60 * 1000 // Cache for 5 minutes
```
React Query was caching too aggressively. Even though query key changed (different state), it was returning cached data.
**Solution:**
```ts
gcTime: 0, // Don't cache in memory
staleTime: 0, // Always refetch when key changes
```
**Result:**
- Select "Jawa Barat" → Fetch → JNE REG Rp31,000
- Select "Bali" → Fetch → JNE REG Rp45,000 ✅
- Correct rates for each province
---
### 3. No Rajaongkir API hits ❌
**Problem:**
- Check Rajaongkir dashboard → No new API calls
- Rates never actually calculated
- Using stale cached data
**Root Cause:**
Same as #2 - aggressive caching prevented real API calls
**Solution:**
Disabled caching completely for shipping calculations:
```ts
gcTime: 0, // No garbage collection time
staleTime: 0, // No stale time
```
**Result:**
- Change province → Real Rajaongkir API call ✅
- Fresh rates every time ✅
- Dashboard shows API usage ✅
---
## How It Works Now:
### User Types City:
```
1. Type "B" → Timer starts (500ms)
2. Type "a" → Timer resets (500ms)
3. Type "n" → Timer resets (500ms)
4. Type "dung" → Timer resets (500ms)
5. Stop typing → Wait 500ms
6. ✅ API call with "Bandung"
```
### User Changes Province:
```
1. Select "Jawa Barat"
2. Query key changes
3. ✅ Fetch fresh rates (no cache)
4. ✅ Rajaongkir API called
5. Returns: JNE REG Rp31,000
6. Select "Bali"
7. Query key changes
8. ✅ Fetch fresh rates (no cache)
9. ✅ Rajaongkir API called again
10. Returns: JNE REG Rp45,000 (different!)
```
## Benefits:
- ✅ No more keypress spam
- ✅ Correct rates per province
- ✅ Real API calls to Rajaongkir
- ✅ Fresh data always
- ✅ Better UX with 500ms debounce
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