I have the following validation method in my viewmodel (example is showing only one column, "ItemNumber"):
public bool IsValid
{
get
{
foreach (string property in ValidatedProperties)
if (GetValidationError(property) != null)
return false;
return true;
}
}
static readonly string[] ValidatedProperties =
{
"ItemNumber"
};
string GetValidationError(string propertyName)
{
if (Array.IndexOf(ValidatedProperties, propertyName) < 0)
return null;
string error = null;
switch (propertyName)
{
case "ItemNumber":
error = this.ValidateItemNumber();
break;
default:
Debug.Fail("Unexpected property being validated on ProjectExpense: " + propertyName);
break;
}
// set the status message on the UI to the generated error
if (error != null)
{
ErrorMessage = error;
}
return error;
}
// string method
static bool IsStringMissing(string value)
{
return String.IsNullOrEmpty(value) || value.Trim() == String.Empty;
}
string ValidateItemNumber()
{
if (SelectedProjectExpenseItem != null)
{
if (IsStringMissing(SelectedProjectExpenseItem.ItemNumber))
{
return "Item number is required";
}
if (SelectedProjectExpenseItem.ItemNumber.Length > 50)
{
return "Item number exceeds 50 characters";
}
}
return null;
}
#endregion
#region IDataErrorInfo Members
string IDataErrorInfo.Error { get { return null; } }
string IDataErrorInfo.this[string propertyName]
{
get { return this.GetValidationError(propertyName); }
}
The validation fires, but I don't know how to communicate it to my datagrid. I am using a separate Dto (hence SelectedProjectExpenseItem.ItemNumber above, SelectedProjectExpenseItem is my Dto) instead of having the properties directly in my viewmodel. Here is my datagrid:
<DataGrid ItemsSource="{Binding Path=ListOfProjectExpenseItems}" AutoGenerateColumns="False"
Name="dgProjectExpenseItems" SelectionMode="Single" SelectionUnit="FullRow" CanUserResizeColumns="True"
SelectedItem="{Binding Path=SelectedProjectExpenseItem, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" GridLinesVisibility="Horizontal" CanUserDeleteRows="True" CanUserAddRows="True">
<DataGrid.Columns>
<DataGridTextColumn Header="ID" Width="SizeToCells" MinWidth="50" Binding="{Binding RowID}" />
<DataGridTextColumn Header="Project Expense ID" Width="SizeToCells" Visibility="Hidden" MinWidth="0" Binding="{Binding ProjectExpenseID, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" />
<DataGridTextColumn Header="Item Number" Width="SizeToCells" MinWidth="140" Binding="{Binding ItemNumber, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" />
<DataGridTextColumn Header="Item Description" Width="SizeToCells" MinWidth="250" Binding="{Binding ItemDescription, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" />
<DataGridTextColumn Header="Unit Price" Width="SizeToCells" MinWidth="90" Binding="{Binding ItemUnitPrice, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" />
<DataGridTextColumn Header="Qty" Width="SizeToCells" MinWidth="65" Binding="{Binding ItemQty, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" />
<DataGridTextColumn Header="Supplier Name" Width="SizeToCells" MinWidth="200" Binding="{Binding SupplierName, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" />
</DataGrid.Columns>
</DataGrid>
I would like to use a style, say with a red border and tooltip stating the error, to signify a problem with the row or cell. Every example I found using styles, however, has the properties directly in the viewmodel, and I cannot figure out how to port it over to my Dto.
Any help is appreciated.