several questions of calculation in class model.

Question

Hi ,

I've made a class model to do a calculation to obtain a result : Id/2022, Id is a variable.

Class model :

 public partial class Developer  
    {   
        [Key]  
        public int DeveloperId{ get; set; }  
        public int Id { get; set; }  
        public DateTime DateCrea {get; set;}  
        public string? YearC {   
            get{   
            return DateCrea.Year.ToString();  
            } set{}}  
        public string ECR {  
            get{  
                 string _currentYear = DateTime.Today.Year.ToString();  
                 int id ;  
                 Id = DeveloperId  
                 if (_currentYear == YearC)  
                 {  
                    id = Math.Max(Id,1) + 1;  
                 }  
                else {id =1 ;}  
                string ecr = id.ToString() + '/' + YearC;  
                return ecr;  
            }  
        }         
    }  

the result of the class is e.g : 2/2022

I've four questions :

• The column ECR is not fill in table but it's rendering in UI. Why the value in column ECR is not write in the table?
• As you can see the result is 002/2022 which is the calculation of max(Id,1)+1. How can I start at 002/2022?
• In UI I 've the possibility to delete a line in my table. I can do that with the controller. When I delete the row in table the Id is no longer a series of numbers. This means if there are 5 rows in the table the Id takes the values from 1 to 5;
  If I delete a line for example line 2 the Id takes the values : Id = 1, Id = 3, Id = 4, Id = 5. Why the Id does not increment itself. How to make the Id auto-increment?
• I would like to add the format 001/2022 i.e. add zeros in front of the Id in the following way: Id takes the values 1 to 9 then the result will be 009/2022 if Id takes the values from 10 to 99 then the result will be 099/2022 ...

Thanks in advance to your help!

Answer 1

Perhaps the following method will get what you want in regards to auto-increment. See it in action here

public class Helpers  
{  
    public static string NextValue(string sender)  
    {  
        string value = Regex.Match(sender, "[0-9]+$").Value;  
        return sender[..^value.Length] + (long.Parse(value) + 1)  
            .ToString().PadLeft(value.Length, '0');  
    }  
}  

Answer 2

I tried your proposition but it doesn't quite do what I want.
Indeed I have to increment with the max of the Id each time that the condition _currentYear == YearC is verified.

The code below make the job :

public string ECR {  
             get{  
                  string _currentYear = DateTime.Today.Year.ToString();  
                  int id ;  
                  Id = DeveloperId  
                  if (_currentYear == YearC)  
                  {  
                     id = Math.Max(Id,1) + 1;  
                  }  
                 else {id =1 ;}  
                 string ecr = id.ToString() + '/' + YearC;  
                 return ecr;  
             }  
         }         

The result is eg :

I have always the question :

• The column ECR is not fill in table but it's rendering in UI. Why the value in column ECR is not write in the table?
• As you can see the result is 002/2022 which is the calculation of max(Id,1)+1. How can I start at 002/2022?
• I would like to add the format 001/2022 i.e. add zeros in front of the Id in the following way: Id takes the values 1 to 9 then the result will be 009/2022 if Id takes the values from 10 to 99 then the result will be 099/2022 ...

Thanks in advance to your help!!