Tim Van Wassenhove

A while ago i presented the SortableBindingList. One of the nice features you get with DataSets is that you can use relations to navigate through the data. Business Objects don’t give you this functionality by default. Today i implemented a BindingList that supports navigation through relations. First i’ll present you the Business Objects:

We would like to create an overview of the appointments using a datagridview:

I drag a datagridview on the designer form, add columns, and then i set the datapropertynames as following: (Notice how i use a . to navigate the relations)

this.dataGridView1.AutoGenerateColumns = false;
this.ColumnId.DataPropertyName = "Id";
this.ColumnPatient.DataPropertyName = "Patient.Name";
this.ColumnMunicipality.DataPropertyName = "Patient.Address.Municipality";
this.ColumnStart.DataPropertyName = "DateTimeRange.Start";
this.ColumnEnd.DataPropertyName = "DateTimeRange.End";

First we need to implement a method that allows us to find a PropertyInfo for the given property name:

public static PropertyInfo Resolve(string propertyName)
{
 Type t = typeof(T);
 PropertyInfo propertyInfo = null;

 string[] subPropertyNames = propertyName.Split('.');
 if (subPropertyNames.Length == 1)
 {
  // a regular property
  propertyInfo = t.GetProperty(propertyName);
 }
 else
 {
  // navigate through the subproperties
  for (int i = 0; i < subPropertyNames.Length - 1; ++i)
  {
   propertyInfo = t.GetProperty(subPropertyNames[i]);
   t = propertyInfo.PropertyType;
  }
 }

 return propertyInfo;
}

Now we are ready to implement the ITypedList.GetItemProperties method in our TypedList:

public PropertyDescriptorCollection GetItemProperties(PropertyDescriptor[] listAccessors)
{
 PropertyDescriptorCollection propertyDescriptors = new PropertyDescriptorCollection(listAccessors);

 // add the regular property descriptors T has
 foreach (PropertyDescriptor propertyDescriptor in TypeDescriptor.GetProperties(typeof(T)))
 {
  propertyDescriptors.Add(propertyDescriptor);
 }

 // add the subproperties
 foreach (string subPropertyName in this.subPropertyNames)
 {
  propertyDescriptors.Add(new SubPropertyDescriptor<T>(subPropertyName));
 }

 return propertyDescriptors;
}

Using this class is as simple as:

// create a TypedList that holds Appointments
TypedBindingList<Appointment> appointments = new TypedBindingList<Appointment>(new string[] { "Patient.Name", "Patient.Address.Municipality", "DateTimeRange.Start", "DateTimeRange.End" });

// Initialise two patients
Patient patient = new Patient(1, "Tim", new Address(1, "MyStreet", 1820, "Melsbroek"));
Patient patient2 = new Patient(2, "John", new Address(2, "His Street", 3000, "Leuven"));

// Add appointsments to the list
appointments.Add(new Appointment(1, patient, new DateTimeRange(new DateTime(2007, 5, 3, 15, 0, 0), new DateTime(2007, 5, 3, 16, 0, 0))));
appointments.Add(new Appointment(2, patient2, new DateTimeRange(new DateTime(2007, 5, 4, 15, 0, 0), new DateTime(2007, 5, 4, 16, 0, 0))));
appointments.Add(new Appointment(3, patient, new DateTimeRange(new DateTime(2007, 5, 5, 15, 0, 0), new DateTime(2007, 5, 5, 16, 0, 0))));
appointments.Add(new Appointment(4, patient, new DateTimeRange(new DateTime(2007, 5, 6, 15, 0, 0), new DateTime(2007, 5, 6, 16, 0, 0))));
appointments.Add(new Appointment(5, patient2, new DateTimeRange(new DateTime(2007, 5, 7, 15, 0, 0), new DateTime(2007, 5, 7, 16, 0, 0))));
appointments.Add(new Appointment(6, patient, new DateTimeRange(new DateTime(2007, 5, 7, 17, 0, 0), new DateTime(2007, 5, 7, 17, 15, 0))));

// Assign this list to the datagridview datasource
this.dataGridView1.DataSource = appointments;

Pretty cool, don’t you think? As always, feel free to download the code: TypedList.zip

Edit: Today, May 8th 2007, i discovered a but in SubPropertyDescriptor.SetValue and uploaded a newer version of the code.