Binding array of arrays or dynamic to a datagrid

Question

I am attempting to bind an array of arrays to a DataGrid.

I am aware that I could do this fairly easily by converting the data to a DataTable and then binding that. BUT this isn't what I need as I need to be able to add groupings to the data via a PagedCollectionVIew.

The reason for doing this is: I have a set of controls that create a structure for a document, I want to reflect this structure with dummy data dynamically while the structure controls are being used. The dummy data is a simple symmetric matrix of random ints where the rows are the data elements, I want to bind each grid column to the elemtns of the array, NOT the array object.

_dataGenerator = new DummyDataGenerator();
_dummyDataView = new ObservableCollection<int[]>();
DummyData = new PagedCollectionView(_dummyDataView);

Where the _dummyDataView is populated by

// Set up the dummy data for the fields available.
_dataGenerator.CreateData(ReportFields).ForEach(_dummyDataView.Add);

and the XAML is just a DataGrid binding to the DummyData... then I will be dynamically adding Groupings and Sortings to is as the user plays with the document data. I have searched everywhere but can't find a solution, but there must be a way (someone must have blogged this) to bind to elements of an array in xaml! Really need some help here.

Answer 1

I have the answer (well I had it ages ago, but I remembered I posted this question). It's a frankencode monster from about a zillion snippets and my own brain, so I can't attribute everyone. I am going to put it up. Because I think it is awesome. Even if nobody else cares:

It uses: - The DLR - A bit of reflection - A bit of IL building.

Should probably put all of this into a blog post somewhere but I don't keep a blog.

This is the code that creates the data for the view called by the ViewModel.

    public IEnumerable<dynamic> CreateData(ObservableCollection<ReportFieldVm> reportFields)
    {
        // Find the length of the array.
        var size = reportFields.Count;

        // Create matrix.
        var b = new int[size, size];

        // Random for the values.
        var rand = new Random((int)DateTime.Now.Ticks);

        // Build the symmetric matrix.
        for (var i = 0; i < size; i++)
        {
            for (var j = 0; j < size; j++)
            {
                if (i == j)
                {
                    b[i,j] = rand.Next(0, 100);
                }
                else
                {
                    var a = rand.Next(0, 100);
                    b[i,j] = a;
                    b[j,i] = a;
                }
            }
        }

        // Define the assembly to add out new type to.
        var asmName = new AssemblyName("DummyAssembly");
        var ab = AppDomain.CurrentDomain.DefineDynamicAssembly(asmName, AssemblyBuilderAccess.Run);
        var mb = ab.DefineDynamicModule("DummyModule");

        // Define our type.
        var d = mb.DefineType("DummyType", TypeAttributes.Public);

        const MethodAttributes GetSetAttr = MethodAttributes.Public | MethodAttributes.SpecialName | MethodAttributes.HideBySig;

        // Define all the fields for the new type.
        foreach (var rf in reportFields.OrderBy(rf => rf.SelectOrder))
        {
            var propertyName = rf.FieldName;

            var field = d.DefineField("m_" + propertyName, typeof(int), FieldAttributes.Private);

            var property = d.DefineProperty(propertyName, PropertyAttributes.HasDefault, typeof(int), null);

            var dGetAccessor = d.DefineMethod("get_" + propertyName, GetSetAttr, typeof(int), Type.EmptyTypes);

            var numberGetIl = dGetAccessor.GetILGenerator();
            numberGetIl.Emit(OpCodes.Ldarg_0);
            numberGetIl.Emit(OpCodes.Ldfld, field);
            numberGetIl.Emit(OpCodes.Ret);

            var dSetAccessor = d.DefineMethod("set_" + propertyName, GetSetAttr, null, new Type[] { typeof(int) });
            var numberSetIl = dSetAccessor.GetILGenerator();
            numberSetIl.Emit(OpCodes.Ldarg_0);
            numberSetIl.Emit(OpCodes.Ldarg_1);
            numberSetIl.Emit(OpCodes.Stfld, field);
            numberSetIl.Emit(OpCodes.Ret);

            property.SetGetMethod(dGetAccessor);
            property.SetSetMethod(dSetAccessor);
        }

        // Create the type.
        var dummyType = d.CreateType();

        var array = new List<dynamic>();

        // Convert the matrix into the array of the dynamic.
        for (var i = 0; i < size; i++)
        {
            var obj = Activator.CreateInstance(dummyType);
            int j = 0;
            foreach (var rf in reportFields.OrderBy(rf => rf.SelectOrder))
            {
                var type = obj.GetType();
                var prop = type.GetProperty(rf.FieldName);
                prop.SetValue(obj, b[j, i], null);
                j++;
            }
            array.Add(obj);
        }

        return array;
    }

This is the code that binds the view, called in the view.

Where :

1. _dynamicReportPreview is the named grid in the XAML.

2. ViewModel is a property that exposes the DataContext of the view set in the view constructor.

   private void BuildPreviewGridColumns()
   {
       if (_dynamicReportPreview == null)
           return;
   
       _dynamicReportPreview.Columns.Clear();
   
       var initialFields = ViewModel.ReportFields.OrderBy(rf => rf.SelectOrder);
   
       foreach (var rf in initialFields)
       {
           var col = new Column
           {
               ColumnName = rf.FieldName, 
               Binding = new Binding(rf.FieldName)
           };
   
           _dynamicReportPreview.Columns.Add(col);
   
           if (!rf.IsVisible)
           {
               col.Visible = false;
           }
       }
   }