controller to delete row in table based on model variable

Question

I have a HttpPost controller which adds a School model booking into the Schools Db (which saves info like School Name, School Date, School Id). Now I need to delete the row in Dates Db which Date is the same Date as the one just entered into School Db e.g. if School model date entered was 13/07/2019, I want to find the row in Dates Db which has the date - 13/07/2019 and then delete this row from the table

My controller so far:

[HttpPost]
    public ActionResult Booking(School model)
    {
        db.Schools.Add(model);
        db.SaveChanges();


        //make chosen school date unavailable in datepicker
        Datepicker date = db.Dates.Find(model.Date); 
        db.Dates.Remove(date);
        db.SaveChanges();

        return RedirectToAction("Booking");
    }

School model (Schools Db context):

namespace BookingSys.Models
{
  public class School
  {
    public DateTime Date { get; set; }
    public int Id { get; set; }
    public string Name { get; set; }
    public string Email { get; set; }
    public int PhoneNumber { get; set; }
  }
}

DatePicker model (Dates Db context):

namespace BookingSys.Models
{
  public class Datepicker
  {
    public DateTime Date { get; set; }
    public int Id { get; set; }
    public int LecturerId { get; set; }
    public string Comment { get; set; }
  }
}

I am currently getting the following error when I click submit in the View to create a School model:

System.ArgumentException: 'The type of one of the primary key values did not match the type defined in the entity. See inner exception for details. Parameter name: keyValues' EntitySqlException: The argument types 'Edm.Int32' and 'Edm.DateTime' are incompatible for this operation. Near WHERE predicate, line 1, column 62.

a busy cat

Thanks in advance

Ok. so what is the error you are having deleting the date from the Date table?. I don't really know the structure of your db but is deleting what you really want? why not have a column say deleted and mark an item as deleted?, there is no Ctrl+Z after deleting. — Bosco
– Bosco, Commented Jul 12, 2019 at 22:51
@bosco I do not want to delete the date field in Dates Db Context, I want to delete the row which has the same date as the date in Schools Db Context. e.g. if School model date entered was 13/07/2019, I want to find the row in Dates Db which has the date - 13/07/2019 and then delete this row from the table — Craig P H
– Craig P H, Commented Jul 12, 2019 at 23:35
Ok. since you want to still delete the row, what is the error you are having with your present code?? — Bosco
– Bosco, Commented Jul 12, 2019 at 23:41

Bosco · Accepted Answer · 2019-07-13 00:00:41Z

1

What you need is the lamda expression and also use First or FirstOrDefault

change this line

Datepicker date = db.Dates.Find(model.Date);

To

Datepicker date = db.Dates.First(m => m.Date == model.Date);

OR

//if you are not sure if the date exists in both tables
Datepicker date = db.Dates.FirstOrDefault(m => m.Date == model.Date); 
// then check for null before deleting

Find() requires the value of the primary key of the table and you need to get the data bay Date

edited Jul 13, 2019 at 0:00

answered Jul 12, 2019 at 23:54

Bosco

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