angularjs ng-repeat checkbox

<div class="col-md-3" ng-repeat="user in title.UserList"> <p class="form-control-static"> <input type="checkbox" ng-checked="user.Role" ng-model="item.UserId[user.UserId]" ng-true-value="'add_{{user.UserId}}'" ng-false-value="'del_{{user.UserId}}'"/>&nbsp;{{user.UserName}} </p> </div>