How to write an empty value for points on Teams?

Question

I'm developing Windows Form app using Graph API. I have Excel file
with data from Teams. Excel columns are: Display name, Feedback, Points,Submission id, OutcomeFeedback id and OutcomePoints id. I want to
update the value of points in the Excel file and write that value on
Teams. The problem is that when I leave the field for points empty, I
get an error. Does anyone know how to solve this? Here is the code: for  ( int  i = 2; i  {          string  cellValue1 = Convert.ToString(excelWorksheet.Cells[i, 2].Value);  //feedback           string  cellValue2 = Convert.ToString(excelWorksheet.Cells[i, 3].Value);  //points           string  cellValue3 = Convert.ToString(excelWorksheet.Cells[i, 4].Value);  //submission id           string  cellValue4 = Convert.ToString(excelWorksheet.Cells[i, 5].Value);  //outcome feedback id           string  cellValue5 = Convert.ToString(excelWorksheet.Cells[i, 6].Value);  //outcome points                 if (cellValue1 ==  null )         {             await GraphHelper.UpdateFeedback( "" ,  this .team_id, assignment_id, cellValue3, cellValue4);         }          else          {             await GraphHelper.UpdateFeedback(cellValue1,  this .team_id, assignment_id, cellValue3, cellValue4);         }               if (cellValue2 ==  null )         {             await GraphHelper.UpdatePoints( "" ,  this .team_id, assignment_id, cellValue3, cellValue5);         }          else   if (Int32.Parse(cellValue2)  = 0)         {             await GraphHelper.UpdatePoints(cellValue2,  this .team_id, assignment_id, cellValue3, cellValue5);         }     }          public   static  async Task UpdatePoints( string  points,  string  teamId,  string  assignmentId,  string  submissionId,  string  outcomeId)     {         graphClient = GetGraphClient(token);              var educationOutcomePoint =  new  EducationPointsOutcome         {             Points =  new  EducationAssignmentPointsGrade             {                 Points = Int32.Parse(points)             }         };              await GraphHelper.graphClient.Education.Classes[teamId].Assignments[assignmentId].Submissions[submissionId].Outcomes[outcomeId]              .Request()             .UpdateAsync(educationOutcomePoint);     }

Jignesh Kumar · Accepted Answer

One more way you can fix. Pass "0" as string where point is null   if (cellValue2 ==  null )           {               await GraphHelper.UpdatePoints( "0" ,  this .team_id, assignment_id, cellValue3, cellValue5);           }

Gordana Tasic · Answer

It works! Thank you very much!