Retrieve selected row (class) from DataGridView as an object class (Unable to cast object)

Question

I have the following class named Students:

namespace ClassLibrary
{
    using System;
    using System.Collections.Generic;

    public partial class Students
    {
        [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2214:DoNotCallOverridableMethodsInConstructors")]
        public Students()
        {
            this.Scenarios = new HashSet<Scenario>();
        }

        public int StudentsID { get; set; }
        public System.DateTime CreatedOn { get; set; }
        public string CreatedBy { get; set; }
        public System.DateTime UpdatedOn { get; set; }
        public string UpdatedBy { get; set; }
        public string StudentsCode { get; set; }
        public string StudentsName { get; set; }
        public bool isActive { get; set; }
        public string Comments { get; set; }

        [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly")]
        public virtual ICollection<Scenario> Scenarios { get; set; }
    }
}

And I load data as a list in a DataGridView. This works fine:

public partial class myCLASS : Form
{
    ...

    private void myCLASS_Load(object sender, EventArgs e)
    {

        myDataGridView.DataSource = (from x in _context.Students
        orderby x.MFlowOrdering
        select new { x.StudentsID,x.StudentsCode,x.StudentsName}).ToList();                                      
    }


    private void myDataGridView_CellContentClick(object sender, DataGridViewCellEventArgs e)
    {
      Students SelectedRow =(Students)(myDataGridView.CurrentRow.DataBoundItem);
      MessageBox.Show(SelectedRow.StudentsID);
    }
    ...
}

Now, I want each time I click on a row in the DataGridView (only full row selection is enabled), I want to retrieve the object (Selected Class Students) behind the selected row:

private void myDataGridView_CellContentClick(object sender, DataGridViewCellEventArgs e)
{
  Students SelectedRow =(Students)(myDataGridView.CurrentRow.DataBoundItem);
  MessageBox.Show(SelectedRow.StudentsID);
}

And I receive the following error:

Additional information: Unable to cast object of type '<>f__AnonymousType0`5[System.Int32,System.Int32,System.String,System.String,System.Boolean]' to type 'ClassLibrary.Students'.

I Google it and it seems that I use the correct syntax.

Could you please advice?

Your sintax is right, but the returned type in in linq is wrong (you specified an anonymous type instead of the ClassLibrary.Students), hence the error. Ashin's answer should work. — Cleptus, Jun 05 '17 at 08:50

ashin · Accepted Answer · 2017-06-05T09:07:51.327

You're using the anonymous type while binding the grid. Try selecting the Students type in the query as follows:

private void myCLASS_Load(object sender, EventArgs e)
{
    myDataGridView.DataSource = (from x in _context.Students
    orderby x.MFlowOrdering
    select new Students { 
                StudentsId = x.StudentsID, 
                StudentsCode = x.StudentsCode, 
                StudentsName = x.StudentsName
    }).ToList();                                      
}

UPDATE

In case an anonymous type is preferred for binding, you could use dynamic keyword instead of casting the data bound item to Students entity as follows:

private void myCLASS_Load(object sender, EventArgs e)
{
    myDataGridView.DataSource = (from x in _context.Students
    orderby x.MFlowOrdering
    select new { 
                StudentsId = x.StudentsID, 
                StudentsCode = x.StudentsCode, 
                StudentsName = x.StudentsName
    }).ToList();                                      
}

private void myDataGridView_CellContentClick(object sender, DataGridViewCellEventArgs e)
{
  dynamic SelectedRow = myDataGridView.CurrentRow.DataBoundItem;
  MessageBox.Show(SelectedRow.StudentsID);
}

hello. I have already tried this one ... but I receive the error "can not initialize type 'Students' with a collection tantalizer because it does not implement 'System.Collections.IENumerable'" — evangelia, Jun 05 '17 at 08:50
could you please share the Students class? I can see that it is marked as partial. — ashin, Jun 05 '17 at 08:51
I have updated the answer to support anonymous binding, please try it — ashin, Jun 05 '17 at 09:09

score 1 · Answer 2 · answered Jun 05 '17 at 08:44

1

You need to configure the DataBinding for the DGV. See example here: DataGridView databinding

answered Jun 05 '17 at 08:44

pitersmx

935
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Retrieve selected row (class) from DataGridView as an object class (Unable to cast object)

2 Answers2