Angular中ng-options下拉数据默认值的设定方法

    <div class="form-group">        <label class="col-sm-2 control-label">教师</label>             <div class="col-sm-10">              <select style="display:block;                  width:100%;                  height:34px;                  padding:6px 12px;                  font-size:14px;                  line-height:1.4;                  border-radius:4px;                  border:1px solid #ccc;                  color:#555; "                  ng-model="editCourse.TeacherName"                  ng-options="Teacher.UserName for Teacher in TeacherList" required>                <option value="">选择教师</option>               </select>             </div>      </div>

    //data为课程的编号ID   $scope.Edit = function (data) {      //通过课程ID获取课程对象      CourseService.getByCourseID(data).then(function (result) {        $scope.editCourse = result.data;        //默认值设定        //先通过课程里面的教师ID获取教师对象        CourseService.GetTeacherByTeacherID(result.data.TeacherID).then(function (result) {         //$scope.TeacherList为所有教师的列表          for (i = 0; i < $scope.TeacherList.length; i++) {            //如果当前课程教师的ID与当前遍历到的教师的ID相等的话就把当前遍历到的这个教师的对象给到 ng-model="editCourse.TeacherName"            if (result.data.UserID == $scope.TeacherList[i].UserID) {              $scope.editCourse.TeacherName = $scope.TeacherList[i];            }          }        });        angular.element("#edit").modal({          show: true        })      })    }