c# design question - standalone GUI application

Question

Hi folks. It's a pleasure to see how much knowledge people have on here, it's a treasure of a place. I've seen myself writing code for DataGridView events - and using DataSource to a backend prepared DataTable object.

Sometimes the user can remove rows, update them etc. and the underlying data will need validation checks again.

Let's assume we have a person class

class Person {
    public string FirstName { get; set; }       
}

Let's say some other part of the code deals with creating an array of Person.

class Processor {
       public static Person[] Create()
       {
           ....
           ....
           return person[];
       }
}

And this information would appear on a DataGridView for user viewing. I've tried something like this:

public static DataTable ToTable(List<Person> list)
{   ...   }

And had this method in the Person class .. which I would think it'd belong to. Then I would bind the DataGridView to that DataTable and the user will then see that data and do their tasks.

But I've thought of using BindingList<> which I'm not so educated on yet.. would I still have the same capability of sorting the DataGridView like it does with DataTable as a DataSource? Would BindingList be implemented by a container class like "PersonCollection" or would the Person class implement itself? I would like to fire some events to be able to modify the collection in a clean way without having to reset datasources, etc. Where the user experience could really be affected.

I understand that modifying the DataSource DataTable is the good way. But sometimes I need to fire methods in the corresponding class that that specific row refers to, and had an ugly extra hidden column which would hold a reference to the existing object somewhere else (the Person reference).

If you guys know a better design solution, I would be more than happy to hear it. Thanks in advance,

PS. After reading "The Pragmatic Programmer", I just can't stop thinking critically about code!

Leo B.

Answer 1

Create a business object class. Implement INotifyPropertyChanged. Look at the code below:

public class Employee:INotifyPropertyChanged
    {
        public Employee(string Name_, string Designation_, DateTime BirthDate_)
        {
            this.Name = Name_;
            this.Designation = Designation_;
            this.BirthDate = BirthDate_;
        }


        #region INotifyPropertyChanged Members
        public event PropertyChangedEventHandler PropertyChanged;
        #endregion

        private void NotifyPropertyChanged(String info)
        {
            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs(info));
            }
        }

        [DisplayName("Employee Name")]
        public string Name
        {
            get { return this._Name; }

            set
            {
                if (value != this._Name)
                {
                    this._Name = value;
                    NotifyPropertyChanged("Name");
                }
            }
        }
        private string _Name = string.Empty;

        [DisplayName("Employee Designation")]
        public string Designation
        {
            get { return this._Designation; }

            set
            {
                if (value != this._Designation)
                {
                    this._Designation = value;
                    NotifyPropertyChanged("Designation");
                }
            }
        }
        private string _Designation = string.Empty;

        public DateTime BirthDate
        {
            get { return this._BirthDate; }

            set
            {
                if (value != this._BirthDate)
                {
                    this._BirthDate = value;
                    NotifyPropertyChanged("BirthDate");
                }
            }
        }
        private DateTime _BirthDate = DateTime.Today;

        [DisplayName("Age")]
        public int Age
        {
            get
            {
                return DateTime.Today.Year - this.BirthDate.Year;
            }
        }
  }

Create your custom collection:

public class EmployeeCollection:BindingList<Employee>
    {
        public new void  Add(Employee emp)
        {
            base.Add(emp);
        }

        public void SaveToDB()
        {
           //code to save to db
        }
    }

Set the data source:

 _employeeStore = new EmployeeCollection(); 
this.dataGridView1.DataBindings.Add("DataSource", this, "EmployeeStore");

Now if you want to add an employee to your datagridview,

Employee employee = new Employee(textBoxName.Text, textBoxDesignation.Text, dateTimePicker1.Value);            
_employeeStore.Add(employee);

This is very clean. You just play with business object and don't touch the UI.

Answer 2

Havent read you question fully, bbut you might want to take a look at my Project ModelShredder, which provides a convinient and fast ToDataTable method