Adding data to a specific column in a DataGrid

Question

I want to create a new column and then add values to only that new column on a button click event. Is that possible? The column might have a few rows underneath it, depending the amount of items in a quote.

What I have achieved so far:

My class where all my information is stored in

public class ViewQuoteItemList
{
    ...
    public double SupplierCost { get; set; }
    ...
}

I can create my column and bind it to my ViewQuoteItemList class

DataGridTextColumn columnFeedbackSupplier = new DataGridTextColumn();
columnFeedbackSupplier.Binding = new Binding("SupplierCost");
//The header of the column gets it's value from a combobox where you select a company to be added to the datagrid
columnFeedbackSupplier.Header = (cmbFeedbackSelectSupplier.SelectedItem as DisplayItems).Name;

From here I get my quote items from a different datagrid and I add them to my second datagrid where I want to add the new column and it's values

IList list = dgFeedbackAddCost.SelectedItems as IList;
IEnumerable<ViewQuoteItemList> items = list.Cast<ViewQuoteItemList>();

var collection = (from i in items
                  let a = new ViewQuoteItemList { SupplierCost = 0 }
                  select a).ToList();

Lastly, I add the new column to the second datagrid and set the collection as the datagrid's ItemSource

dgFeedbackSelectSupplier.Columns.Add(columnFeedbackSupplier);
dgFeedbackSelectSupplier.ItemsSource = collection;

My problem is that once I edit a cell of data from one of the suppliers, the whole row gets updated with that one value, because it's all bound to one class/item source. Can this be fixed?

EDIT:

"The whole row gets updated" means that every time I insert a value into one cell in a row, every single cell in that row gets updated with the same value. Here are some pictures showing what I mean. I want to edit all the data and this all happens on my second datagrid(dgFeedbackSupplier).

Here, I have two companies added with the 4 items that I want to compare prices with. Now I want to click on a single cell underneath a company and add a value for a certain item.

Here I double click on a cell to edit/change the value.

Then when I change my value in the selected cell, every other company's value for that specific item in the same row gets updated with that same value.

That's my problem and I need to have only that one cell's value changed, and not the whole row.

EDIT 2:

How can I convert this collection to ExpandoObject?

var collection = (from i in items
                  let a = new ViewQuoteItemList { Item = i.Item, Supplier = 25 }
                  select a).ToList();

EDIT 3:

My XAML:

<DataGrid x:Name="dgFeedbackSelectSupplier"  Margin="245,266,0,32" BorderBrush="#FFADADAD" ColumnWidth="*" AutoGenerateColumns="True" CanUserAddRows="False">
    <DataGrid.Columns>
        <DataGridTextColumn x:Name="columnFeedbackSupplierItem" IsReadOnly="True" Header="Item" Binding="{Binding Item}"/>
    </DataGrid.Columns>
</DataGrid>

And this is how my whole method looks like at the moment where I add my Columns and where I get the items from my other datagrid:

    private void btnFeedbackSelectSupplier_Click(object sender, RoutedEventArgs e)
    {
        supplier.Id = (cmbFeedbackSelectSupplier.SelectedItem as DisplayItems).Id;//Not using yet
        supplier.Name = (cmbFeedbackSelectSupplier.SelectedItem as DisplayItems).Name;

        DataGridTextColumn columnFeedbackSupplier = new DataGridTextColumn();
        columnFeedbackSupplier.Binding = new Binding("Supplier") { Mode = BindingMode.TwoWay };
        columnFeedbackSupplier.CanUserReorder = true;
        columnFeedbackSupplier.CanUserResize = true;
        columnFeedbackSupplier.IsReadOnly = false;

        columnFeedbackSupplier.Header = supplier.Name;

        dgFeedbackAddCost.SelectAll();

        IList list = dgFeedbackAddCost.SelectedItems as IList;
        IEnumerable<ViewQuoteItemList> items = list.Cast<ViewQuoteItemList>();

        var collection = new List<ExpandoObject>();
        foreach (var i in items)
        {
            dynamic a = new ExpandoObject();
            a.Id = (cmbFeedbackSelectSupplier.SelectedItem as DisplayItems).Id;
            a.Item = i.Item;
            a.Supplier = 25;
            collection.Add(a);
        }

        dgFeedbackSelectSupplier.Columns.Add(columnFeedbackSupplier);
        dgFeedbackSelectSupplier.ItemsSource = collection;
    }

Answer 1

May I propose another approach? From what I understand;

You have suppliers and these suppliers have items. You can add new suppliers. I assumed suppliers may not have all the items (for a challenge :)).

You want to present this data structure in a grid like view.

The problem here is that you are trying to display a non-tabular data with a tabular view component. What you have is hierarchical data. Before I continue with my solution here are some screen shots.

What I basically did here is to create new views on the hierarchical data, filling the gaps and turn it into a tabular form. I used fake classes for the empty slots so I could easily select the proper datatemplates in XAML. I avoided to use any custom code and kept everything in MVVM+XAML way. So bindings and such works as expected.

The new views had to be updated when the collections changed, so I used the messenger class from MVVMLight for easy implementation, and called RaisePropertyChanged events manually.

In XAML I used ItemsControl and UniformGrid components to create the grid like view.

I put the complete solution on GitHub: https://github.com/orhtun/GridLikeViewWithDynamicColumns

It creates random data on each run. If you get build errors, try right click on the solution and Restore NuGet Packages.