C# creating 2 rows, the first one is a text view list and the second is a comb box list

Question

My project is a C# application to import data from an excel sheet to the database and prompt the user to map them manually.

I need to create two rows:

The first row is a DataGridTextColumn where the excel's headers fit to.
The second row is a DataGridComboBoxColumn having the column_name of the data base

Each one of the DataGridTextColumn have a combo box.

But I'm facing a problem where I'm not able to make the DataGridComboBoxColumn work, every time I launch the application, the first row is working normally but the second row is empty

code :

foreach (DataRow row in dt.Rows)
{
     DataGridTextColumn dgtc = new DataGridTextColumn();
     dgtc.MinWidth = 100;
     dgtc.CanUserSort = false;
     dgtc.Header = row["Column_name"].ToString();
     dg.Columns.Add(dgt);
     DataGridComboBoxColumn dgcbc = new DataGridComboBoxColumn();
     dgcbc.ItemsSource = columnList;
     dgcbc.MinWidth = 100;
     dg2.Columns.Add(dgcbc);
}

xaml :

 <DataGrid x:Name="dg" HorizontalAlignment="Left" Height="29" Margin="11,72,0,0" VerticalAlignment="Top" Width="579"/>
 <DataGrid x:Name="dg2" HorizontalAlignment="Left" Height="30" Margin="11,106,0,0" VerticalAlignment="Top" Width="579"/>

live view:

screenshot

the code is working but the combo boxes are always showing empty fields.

any help on why DataGridComboBoxColumn is not working for me ?

What and where is `columnList` coming from? I'm guessing that is either `null` or empty... — Chris Badman, Oct 17 '14 at 12:01
SqlConnection conn = new SqlConnection("server=***;database=***;Integrated Security = true"); string[] restrictions = new string[4] { null, null, "orders", null }; conn.Open(); var columnList = conn.GetSchema("Columns", restrictions).AsEnumerable().Select(s => s.Field("Column_Name")).ToList(); That was enough to make sure that columnList is not null and it has 4 Strings, i even tested it.. — Salwa Najm, Oct 17 '14 at 16:55

too · Accepted Answer · 2014-10-20T08:45:07.263

There are 2 issues you might be referring to. First one is that setting dgcbc.ItemsSource = columnList is not enough to make ComboBox display list of items to choose from.

Depending on the type of columnList you need to set DisplayMemberPath and SelectedValuePath properties, for example:

var columnList = new Dictionary<string, string>
{
    { "123", "test 123" },
    { "aaa", "test aaa" },
    { "qwe", "test qwe" }
};

dgcbc.ItemsSource = columnList;
dgcbc.DisplayMemberPath = "Key";
dgcbc.SelectedValuePath = "Value";

Another issue is binding of the column to the ItemsSource which is set on your DataGrid object(s).

dg2.ItemsSource = dt;
dgcbc.TextBinding = new Binding(string.Format("[{0}]", "Column_Name");

You might also wonder how to display text in DataGridTextColumn:

dgtc.Binding = new Binding(string.Format("[{0}]", "Column_Name");

I am unsure if this is what you want to achieve for column mapping, probably you would like to modify a header template of the grid and present the grid data as text below. To do this use ~~DataGridTemplateColumn~~ DataGridTextColumn column with both header Label and ComboBox in it's header. hope it helps.

Edit:

I prepared a quick and dirty code only solution.

XAML:

<DataGrid x:Name="dg" Grid.Row="0" AutoGenerateColumns="False"/>

Code behind:

        // data is a rough equivalent of DataTable being imported
        var data = new List<Dictionary<string, string>>
        {
            new Dictionary<string, string> { { "column1", "asd asfs af" }, { "column2", "45dfdsf d6" }, { "column3", "7hgj  gh89" } },
            new Dictionary<string, string> { { "column1", "aaasdfda" }, { "column2", "45sdfdsf 6" }, { "column3", "78gh jghj9" } },
            new Dictionary<string, string> { { "column1", "s dfds fds f" }, { "column2", "4dsf dsf 56" }, { "column3", "78gh jgh j9" } },
        };

        // a list of columns to map to
        var importToColumns = new List<string>
        {
            "123",
            "aaa",
            "qwe",
            "456",
            "bbb"
        };

        importMappings = new Dictionary<string, int>();
        foreach(var column in data[0])
        {
            importMappings.Add(column.Key, -1);
        }

        foreach(var r in importMappings)
        {
            var dgtc = new DataGridTextColumn();
            dgtc.Binding = new Binding(string.Format("[{0}]", r.Key));
            var sp = new StackPanel();
            dgtc.Header = sp;
            sp.Children.Add(new Label { Content = r.Key });
            var combo = new ComboBox();
            sp.Children.Add(combo);
            combo.ItemsSource = importToColumns;
            var selectedBinding = new Binding(string.Format("[{0}]", r.Key));
            selectedBinding.Source = importMappings;
            combo.SetBinding(Selector.SelectedIndexProperty, selectedBinding);
            dgtc.MinWidth = 100;
            dgtc.CanUserSort = false;
            dg.Columns.Add(dgtc);
        }

        dg.ItemsSource = data;
    }

    private Dictionary<string, int> importMappings;

After selection has been approved, importMappings will contain a list of mappings of columns - for each import file column it will contain an index of element in importToColumns list or -1 if no elements were selected.

now that thanks to you i know my question.. how to implement a DataGridTemplateColumn column with both header Label and ComboBox in it. unfortunately it's been 3 days of researches and yet nothing.. — Salwa Najm, Oct 17 '14 at 19:05
I did some configuration to the code but thanks it helped me a lot. — Salwa Najm, Oct 20 '14 at 15:56

C# creating 2 rows, the first one is a text view list and the second is a comb box list

1 Answers1