Btukfyl

I have a collection of objects and each object contains a property of the type collection. My goal is to generate dynamically the datagrid columns based on the collection content and generate also the columns for the remaining properties, which are base types. It is important that a bool is displayed as a CheckBox.

My problem is: The resulting cell content of the dynamically generated columns would be an object (Trait in my object structure), and I want one of this objects properties to be displayed (Trait.Value). When I change content of a cell, the object behind should update.

• I thought of a DataTable, but when I add a row I need the column key and the value. When I set the value to a custom object, I couldn't see any possibility to display and edit a single property of the custom object.


• Second approach would be using dynamic objects, like in the following article:
  Auto-Generating DataGrid Columns From DynamicObjects
  , but I see the same proplem like DataTable
  Additional Information:


• I am using mvvm (when it's necessary I would break this pattern)


• the datagrid should be editable

My object structure:

public class Model

{

    //ItemsSource

    public ObservableCollection<Person> Persons { get; set; }

}



public class Person

{

    public string Name { get; set; }



    //Generate Treats.Count columns

    public ObservableCollection<Treat> Treats { get; set; }

}



public class Treat

{

    //column header name

    public string Name { get; set; }



    //value that should be displayed

    public string Value { get; set; }

}

My ViewModel.cs with sample data:

public class ViewModel

{

    public Model Model { get; set; }



    public ViewModel()

    {

        #region Sample Data

        Model = new Model()

        {

            Persons = new ObservableCollection<Person>()

            {

                new Person()

                {

                    Name = "Peter",

                    Treats = new ObservableCollection<Treat>()

                    {

                        new Treat()

                        {

                            Name = "Look1",

                            Value = "Nice"

                        },

                        new Treat()

                        {

                            Name = "Look2",

                            Value = "Super Nice"

                        }

                    }

                },

                new Person()

                {

                    Name = "Manuel",

                    Treats = new ObservableCollection<Treat>()

                    {

                        new Treat()

                        {

                            Name = "Look1",

                            Value = "Bad"

                        },

                        new Treat()

                        {

                            Name = "Look2",

                            Value = "Super Bad"

                        }

                    }

                }

            }

        };

        #endregion

    }

}

Information to class Model.cs:

• property Persons is the binding collection, which should be used as the ItemsSource


• the columns of the datagrid should be generated based on the object Person. One column for the Name and n columns for the collection Treats.

The result based on my sample data is something like this:

Since, you have said you are okay to break MVVM pattern, please try the below approach.

OVERVIEW:

1. Create a IvalueConverter to convert your itemsource to list of expandoobejcts




2. In Code behind of the DataGrid (Loaded Event or SourceChanged event), add a code to generate columns manually

CODES:

Create Converter: PART 1 First we need to get the List of all possible columsn that might pop in (since we don't know the collections yet)

        ObservableCollection<Person> inputlist = (ObservableCollection<Person>)value;

        List<string> PossibleColumnList = new List<string>();

        PossibleColumnList.Add(nameof(Person.Name)); //since we need name header first.

        List<string> TempColumnList = new List<string>();

        foreach (Person P in inputlist)

        {

           foreach(Treat T in P.Treats)

            {

                if (TempColumnList.Contains(T.Name) == false) TempColumnList.Add(T.Name);

            }

        }

        TempColumnList.Sort();

        PossibleColumnList.AddRange(TempColumnList); //This way we get Name first and rest of the columns in sorted out manner

Create Converter: PART 2. Now create an IDictionary Object with all available colum headers

 IDictionary<string, object> ColumnHeaderDictionary = new Dictionary<string, object>(); 

        foreach (string columnheader in PossibleColumnList)

        {

            if (ColumnHeaderDictionary.ContainsKey(columnheader) == false) ColumnHeaderDictionary.Add(columnheader, new object());

        }

Create Converter: PART 3 Now iterate through all persons and create a IDictionary for each person model. Convert idictionary to expando object and store in final list

List<ExpandoObject> FinalList = new List<ExpandoObject>();



        foreach (Person p in inputlist)

        {

            ExpandoObject tempExpando = new ExpandoObject();

            IDictionary<string, object> TempDictionary = tempExpando as IDictionary<string, object>;

            foreach (var kvp in ColumnHeaderDictionary)

            {

                TempDictionary.Add(kvp);

            }

            TempDictionary[nameof(Person.Name)] = p.Name;

            foreach(Treat t in p.Treats)

            {

                TempDictionary[t.Name] = t.Value;

            }



            FinalList.Add(tempExpando);

        }

        return FinalList;

XAML CODE:

 <Window.DataContext>

    <local:ViewModel/>

</Window.DataContext>

<Grid x:Name="grdMain" DataContext="{Binding}">

    <DataGrid x:Name="dgMain" ItemsSource="{Binding ElementName=grdMain,Path=DataContext.Model.Persons,Converter={StaticResource NewConverter}}" Loaded="dgMain_Loaded" />

    </Grid>

CODE BEHIND: TO MANUALLY CREATE COLUMNS

private void dgMain_Loaded(object sender, RoutedEventArgs e)

    {

        DataGrid workinggrid = sender as DataGrid;

        ExpandoObject SingleExpando = (workinggrid.ItemsSource as List<ExpandoObject>).FirstOrDefault();

        if (workinggrid == null) workinggrid = new DataGrid();





        List<string> ColumHeaders = (SingleExpando as IDictionary<string, object>).ToList().Select(p => p.Key).ToList();



        foreach (string ColumnName in ColumHeaders)

        {

            var newcolumn = new DataGridTextColumn() { Header = ColumnName, Binding = new Binding(ColumnName) };

            workinggrid.Columns.Add(newcolumn);

        }

    }

FINAL OUTPUT: