WPF Row Validation for Primary Key Field

Question

I have been researching this topic for hours and can't find a solution that works for me.

I have a simple WPF program that uses a datagrid to display a list of objects from the code (in very much the same way as the msdn demo)

My data is taken from a SQL database and placed into a list of objects which is bound to the datagrid as below:

public PersonInfo()
{
    InitialiseComponent();
    LoadPeopleFromSQL();
}

public void LoadPeopleFromSQL()
{
    DataSet ds = GetDataSet(SQLConnectionString);
    List<PersonInfo> personList = new List<PersonInfo>();
    foreach(DataRow row in ds.Tables[0].Rows)
    {
        personList.Add(new PersonInfo(row[0], row[1], row[2]));
    }
PersonDataGrid.ItemsSource = personList;

I have set up a ValidationRule class containing a public override ValidationResult Validate() method that exactly matches the structure msdn example: http://msdn.microsoft.com/en-us/library/system.windows.controls.datagrid.rowvalidationrules%28v=vs.110%29.aspx (except that it uses my 'Person' object rather than a 'Course' object)

public class CourseValidationRule : ValidationRule
{
    public override ValidationResult Validate(object value,
        System.Globalization.CultureInfo cultureInfo)
    {
        Course course = (value as BindingGroup).Items[0] as Course;
        if (course.StartDate > course.EndDate)
        {
            return new ValidationResult(false,
                "Start Date must be earlier than End Date.");
        }
        else
        {
            return ValidationResult.ValidResult;
        }
    }
}

//Xaml snippet
<DataGrid.RowValidationRules>
  <local:CourseValidationRule ValidationStep="UpdatedValue"/>
</DataGrid.RowValidationRules>

However, what I would like to do now is search through the rest of the items in the datagrid and check to make sure the PersonInfo.ID field has not been duplicated. I found this code:http://www.codeproject.com/Articles/30905/WPF-DataGrid-Practical-Examples#valid_dataset

But this example expects the BindingGroup object to return a datarow, not a class object.

I noticed that the BindingGroup object has a property called 'Owner' which appears to contain a datarow. However I am using .net 4 and can't access the 'Owner' property.

Please can someone show me how to validate my primary key? Or help me access the BindingGroup.Owner property from within .net 4 (which I believe would fix my issue)

Answer 1

The issue here was transferring my full list of 'People' from my main working class to the DataRowValidation class.

As I could not find a way to bind to the DataRow object, I placed a public property inside the DataRowValidation class and filled it with the current list of people from my main class:

public class DataRowValidation : ValidationRule
{
    public List<PersonInfo> People {get; set;}
    public override ValidationResult Validate(object value, System.Globalization.CultureInfo cultureInfo)
    {
        if (value is BindingGroup)
        {
            BindingGroup group = (BindingGroup)value;
            People = PersonClass.personList;

            //Code to loop through list and test for duplicates
        }
     }
}