Help with InvalidCastException
- by Robert
I have a gridview and, when a record is double-clicked, I want it to open up a new detail-view form for that particular record.
As an example, I have created a Customer class:
using System;
using System.Data;
using System.Configuration;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data.SqlClient;
using System.Collections;
namespace SyncTest
{
#region Customer Collection
public class CustomerCollection : BindingListView<Customer>
{
public CustomerCollection() : base()
{
}
public CustomerCollection(List<Customer> customers) : base(customers)
{
}
public CustomerCollection(DataTable dt)
{
foreach (DataRow oRow in dt.Rows)
{
Customer c = new Customer(oRow);
this.Add(c);
}
}
}
#endregion
public class Customer : INotifyPropertyChanged, IEditableObject, IDataErrorInfo
{
private string _CustomerID;
private string _CompanyName;
private string _ContactName;
private string _ContactTitle;
private string _OldCustomerID;
private string _OldCompanyName;
private string _OldContactName;
private string _OldContactTitle;
private bool _Editing;
private string _Error = string.Empty;
private EntityStateEnum _EntityState;
private Hashtable _PropErrors = new Hashtable();
public event PropertyChangedEventHandler PropertyChanged;
private void FirePropertyChangeNotification(string propName)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(propName));
}
}
public Customer()
{
this.EntityState = EntityStateEnum.Unchanged;
}
public Customer(DataRow dr)
{
//Populates the business object item from a data row
this.CustomerID = dr["CustomerID"].ToString();
this.CompanyName = dr["CompanyName"].ToString();
this.ContactName = dr["ContactName"].ToString();
this.ContactTitle = dr["ContactTitle"].ToString();
this.EntityState = EntityStateEnum.Unchanged;
}
public string CustomerID
{
get
{
return _CustomerID;
}
set
{
_CustomerID = value;
FirePropertyChangeNotification("CustomerID");
}
}
public string CompanyName
{
get
{
return _CompanyName;
}
set
{
_CompanyName = value;
FirePropertyChangeNotification("CompanyName");
}
}
public string ContactName
{
get
{
return _ContactName;
}
set
{
_ContactName = value;
FirePropertyChangeNotification("ContactName");
}
}
public string ContactTitle
{
get
{
return _ContactTitle;
}
set
{
_ContactTitle = value;
FirePropertyChangeNotification("ContactTitle");
}
}
public Boolean IsDirty
{
get
{
return ((this.EntityState != EntityStateEnum.Unchanged) || (this.EntityState != EntityStateEnum.Deleted));
}
}
public enum EntityStateEnum
{
Unchanged,
Added,
Deleted,
Modified
}
void IEditableObject.BeginEdit()
{
if (!_Editing)
{
_OldCustomerID = _CustomerID;
_OldCompanyName = _CompanyName;
_OldContactName = _ContactName;
_OldContactTitle = _ContactTitle;
}
this.EntityState = EntityStateEnum.Modified;
_Editing = true;
}
void IEditableObject.CancelEdit()
{
if (_Editing)
{
_CustomerID = _OldCustomerID;
_CompanyName = _OldCompanyName;
_ContactName = _OldContactName;
_ContactTitle = _OldContactTitle;
}
this.EntityState = EntityStateEnum.Unchanged;
_Editing = false;
}
void IEditableObject.EndEdit()
{
_Editing = false;
}
public EntityStateEnum EntityState
{
get
{
return _EntityState;
}
set
{
_EntityState = value;
}
}
string IDataErrorInfo.Error
{
get
{
return _Error;
}
}
string IDataErrorInfo.this[string columnName]
{
get
{
return (string)_PropErrors[columnName];
}
}
private void DataStateChanged(EntityStateEnum dataState, string propertyName)
{
//Raise the event
if (PropertyChanged != null && propertyName != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
//If the state is deleted, mark it as deleted
if (dataState == EntityStateEnum.Deleted)
{
this.EntityState = dataState;
}
if (this.EntityState == EntityStateEnum.Unchanged)
{
this.EntityState = dataState;
}
}
}
}
Here is my the code for the double-click event:
private void customersDataGridView_CellDoubleClick(object sender, DataGridViewCellEventArgs e)
{
Customer oCustomer = (Customer)customersBindingSource.CurrencyManager.List[customersBindingSource.CurrencyManager.Position];
CustomerForm oForm = new CustomerForm();
oForm.NewCustomer = oCustomer;
oForm.ShowDialog(this);
oForm.Dispose();
oForm = null;
}
Unfortunately, when this code runs, I receive an InvalidCastException error stating "Unable to cast object to type 'System.Data.DataRowView' to type 'SyncTest.Customer'".
This error occurs on the very first line of that event:
Customer oCustomer = (Customer)customersBindingSource.CurrencyManager.List[customersBindingSource.CurrencyManager.Position];
What am I doing wrong?... and what can I do to fix this? Any help is greatly appreciated.
Thanks!
