WPF: bind to a List inside a class – Education Career Blog

I have a File class defined as following

public class File
{
 public string FileName {set;get;}
 public List<Property> PropertyList;
}

Here is how Property class looks like:

public class Property
{
 public string PropertyName { set; get;};
 public string PropertyValue { set; get;};
 ...
}

I need to bind a List<File> to a DataGrid, display FileName. Also, I want to create a column for each Property in the PropertyList,
with the string value of PropertyName as the column title, and string value of PropertyValue as the value of the column.

Is this possible in WPF?

Thanks,

,

Just had to try this one, odd but funny problem:-) Managed to get it working by using the following.
Sorry for the long answer, probably way to detailed 🙂

First of, the DataGrid. Plain and simple

<DataGrid Name="c_dataGrid" AutoGenerateColumns="False"
          CanUserAddRows="False" CanUserDeleteRows="False"/>

Then the File class, named MyFile

public class MyFile
{
    public MyFile() : this(string.Empty) {}
    public MyFile(string fileName)
    {
        FileName = fileName;
        MyPropertyList = new ObservableCollection<MyProperty>();
    }

    public string FileName
    {
        set;
        get;
    }
    public ObservableCollection<MyProperty> MyPropertyList
    {
        get;
        set;
    }
}

Property class, named MyProperty

public class MyProperty
{
    public MyProperty() : this(string.Empty, string.Empty) {}
    public MyProperty(string propertyName, string propertyValue)
    {
        MyPropertyName = propertyName;
        MyPropertyValue = propertyValue;
    }
    public string MyPropertyName
    {
        set;
        get;
    }
    public string MyPropertyValue
    {
        set;
        get;
    }
}

A list containing MyFiles

public ObservableCollection<MyFile> MyFileList{ get; set; }

Created some dummy data to populate the list and set the ItemsSource on the DataGrid

MyFile myFile1 = new MyFile("MyFile1");
myFile1.MyPropertyList.Add(new MyProperty("Name1", "Value1"));
myFile1.MyPropertyList.Add(new MyProperty("Name2", "Value2"));
myFile1.MyPropertyList.Add(new MyProperty("Name3", "Value3"));
MyFile myFile2 = new MyFile("MyFile2");
myFile2.MyPropertyList.Add(new MyProperty("Name1", "Value1"));
myFile2.MyPropertyList.Add(new MyProperty("Name4", "Value4"));
myFile2.MyPropertyList.Add(new MyProperty("Name5", "Value5"));
MyFileList = new ObservableCollection<MyFile>();
MyFileList.Add(myFile1);
MyFileList.Add(myFile2);
c_dataGrid.ItemsSource = MyFileList;

Added a DataGridTextColumn for the FileName attribute

c_dataGrid.Columns.Add(GetNewMyFileNameColumn());

private DataGridColumn GetNewMyFileNameColumn()
{
    DataGridTextColumn myFileNameColumn = new DataGridTextColumn();
    myFileNameColumn.Header = "FileName";
    myFileNameColumn.Width = new DataGridLength(1.0, DataGridLengthUnitType.Auto);

    Binding valueBinding = new Binding();
    valueBinding.Path = new PropertyPath("FileName");
    valueBinding.Mode = BindingMode.TwoWay;
    valueBinding.UpdateSourceTrigger = UpdateSourceTrigger.PropertyChanged;
    valueBinding.NotifyOnSourceUpdated = true;
    valueBinding.NotifyOnTargetUpdated = true;

    myFileNameColumn.Binding = valueBinding;

    return myFileNameColumn;
}

And then for the MyPropertyList. I only wanted to add each MyPropertyName once so if I have the following
MyFile1
-Name1
-Name2
-Name3
MyFile2
-Name1
-Name4
-Name5
the generated columns shall be Name1, Name2, Name3, Name4 and Name5.

foreach (MyFile myFile in MyFileList)
{
    foreach (MyProperty myProperty in myFile.MyPropertyList)
    {
        if (ColumnAlreadyAdded(myProperty.MyPropertyName) == false)
        {
            c_dataGrid.Columns.Add(GetNewMyPropertyColumn(myProperty.MyPropertyName));
        }
    }
}

private bool ColumnAlreadyAdded(string myPropertyName)
{
    foreach (DataGridColumn dataGridColumn in c_dataGrid.Columns)
    {
        if (dataGridColumn.Header.ToString() == myPropertyName)
        {
            return true;
        }
    }
    return false;
}

private DataGridColumn GetNewMyPropertyColumn(string myPropertyName)
{
    DataGridTextColumn myFileNameColumn = new DataGridTextColumn();
    myFileNameColumn.Header = myPropertyName;
    myFileNameColumn.Width = new DataGridLength(1.0, DataGridLengthUnitType.Auto);

    Binding valueBinding = new Binding();
    valueBinding.Path = new PropertyPath("MyPropertyList");
    valueBinding.Converter = new MyPropertyConverter(myPropertyName);
    valueBinding.Mode = BindingMode.TwoWay;
    valueBinding.UpdateSourceTrigger = UpdateSourceTrigger.PropertyChanged;
    valueBinding.NotifyOnSourceUpdated = true;
    valueBinding.NotifyOnTargetUpdated = true;

    myFileNameColumn.Binding = valueBinding;

    return myFileNameColumn;
}

I had to feed the MyPropertyName to the constructor of the Converter so it would know which property to look for.
And finally the Converter

public class MyPropertyConverter : IValueConverter
{
    private string m_propertyName = string.Empty;
    ObservableCollection<MyProperty> m_myPropertyList = null;

    public MyPropertyConverter(string propertyName)
    {
        m_propertyName = propertyName;
    }

    object IValueConverter.Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        m_myPropertyList = value as ObservableCollection<MyProperty>;
        if (m_myPropertyList == null)
        {
            return null;
        }
        foreach (MyProperty myProperty in m_myPropertyList)
        {
            if (myProperty.MyPropertyName == m_propertyName)
            {
                return myProperty.MyPropertyValue;
            }
        }
        return null;
    }

    object IValueConverter.ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        if (m_myPropertyList != null)
        {
            foreach (MyProperty myProperty in m_myPropertyList)
            {
                if (myProperty.MyPropertyName == m_propertyName)
                {
                    myProperty.MyPropertyValue = value.ToString();
                    break;
                }
            }
        }
        return m_myPropertyList;
    }
}

In Convert it will check for the given MyPropertyName and if it finds it, return the MyPropertyValue, otherwise null. The same goes for the ConvertBack method but it will set MyPropertyValue to the new value for the MyProperty with the given MyPropertyName and then return the list which is either a list or null.

The properties that aren’t in a MyFile list won’t be editable, they will just change back to null upon leaving the cell (which is probably the point).

This will result in a DataGrid that looks like this.

alt text

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