Plan date has to be more than start date

app/Http/Controllers/AssignMaterialController.php

@@ -5,6 +5,7 @@ namespace App\Http\Controllers;
 use Illuminate\Http\Request;
 use App\Models\AssignMaterial;
 use App\Models\RequestMaterial;
+use App\Models\Activity;
 use App\Models\ReportActivityMaterial;
 use Datatables;
 
@@ -23,23 +24,30 @@ class AssignMaterialController extends Controller
 			'qty_planning' => 'required'
 		]);
 
+		$activity = Activity::where('id', $request->activity_id)->first();
+
 		$checkStock = RequestMaterial::where("id", $request->material_id)->first();
 		$currentStock = $checkStock->qty;
 		if((int)$currentStock < (int)$request->qty_planning){
 			return response()->json(['status'=>'failed','message'=>'Stock is not enough!','code'=> 500]);
 		}
+		
+		$start_date = $activity->start_date;
+		$start_date = substr($start_date, 0, 19); // remove the timezone offset
+		$startDate = new \DateTime(date("Y-m-d", strtotime($start_date)));
+		$planDate = new \DateTime(date("Y-m-d", strtotime($request->plan_date)));
 
 		$data = $request->all();
 		$data['created_by'] = $this->currentName;
 		$data['budget'] = $checkStock->price;
 		$data['qty_planning'] = $this->sanitizeDecimal($data['qty_planning']);
 
-		$result = AssignMaterial::create($data);
-		if(!$result)
-			return response()->json(['status'=>'failed','message'=>'Failed to add data!','code'=> 500]);
-
-		return response()->json(['status'=>'success','message'=>'Data added!', 'code'=>200]);
-
+		if ($planDate > $startDate) {
+			$result = AssignMaterial::create($data);
+			return response()->json(['status'=>'success','message'=>'Data added!', 'code'=>200], 200);
+		}else{
+			return response()->json(['status'=>'failed','message'=>'Failed to add data!','code'=> 400], 400);
+		}
 	}
 
 	public function update(Request $request, $id){