Own CollectionView for paging, sorting and filtering

Question

I've implemented my own CollectionView to bind a collection of data to a DataGrid in WPF.

The main goal was the pagination, which is working quite well. I've written the following C# code:

public class SchemesCollectionView : CollectionView
{
    private readonly IList<Scheme> innerList;
    private readonly int itemsPerPage;

    private int currentPage = 1;

    public SchemesCollectionView(IList<Scheme> source, int itemsPerPage)
        : base(source)
    {
        innerList = source;
        this.itemsPerPage = itemsPerPage;
    }

    public override int Count
    {
        get { return itemsPerPage; }
    }

    public int CurrentPage
    {
        get { return currentPage; }
        set
        {
            currentPage = value;
            OnPropertyChanged(new PropertyChangedEventArgs("CurrentPage"));
            OnPropertyChanged(new PropertyChangedEventArgs("FirstItemNumber"));
            OnPropertyChanged(new PropertyChangedEventArgs("LastItemNumber"));
        }
    }

    public int ItemsPerPage { get { return this.itemsPerPage; } }

    public int PageCount
    {
        get
        {
            return (this.innerList.Count() + this.itemsPerPage - 1)
                / this.itemsPerPage;
        }
    }

    public int LastItemNumber
    {
        get
        {
            var end = currentPage * itemsPerPage - 1;
            end = (end > innerList.Count()) ? innerList.Count() : end;

            return end + 1;
        }
    }

    public int StartIndex
    {
        get { return (currentPage - 1) * itemsPerPage; }
    }

    public int FirstItemNumber
    {
        get { return ((currentPage - 1) * itemsPerPage) + 1; }
    }

    public override object GetItemAt(int index)
    {
        var offset = index % (ItemsPerPage);

        var position = StartIndex + offset;

        if (position >= innerList.Count)
        {
            position = innerList.Count - 1;
        }

        return innerList[position];
    }

    public void MoveToNextPage()
    {
        if (CurrentPage < PageCount)
        {
            CurrentPage += 1;
        }
        Refresh();
    }

    public void MoveToPreviousPage()
    {
        if (CurrentPage > 1)
        {
            CurrentPage -= 1;
        }
        Refresh();
    }

    public void MoveToFirstPage()
    {
        CurrentPage = 1;
        Refresh();
    }

    public void MoveToLastPage()
    {
        CurrentPage = PageCount;
        Refresh();
    }
}

As mentioned, the pagination works very well. But I can't get the filtering and sorting work. When I add a custom filter to the Filter property, It gets completely ignored. The same with the sorting. I can see the arrows on the column headers after I clicked them, but the different sorting is not reflected within the DataGrid.

What I'm missing here? Hope someone can help.

Answer 1

As mentioned in this, you can take code from Silverlight and use that in WPF.

Paged Collection View in WPF

Answer 2

Here is a solution for filtering and paging using only the CollectionView class.

You just need to set the current page index and max items per page to fits your needs.

        // obtenir la CollectionView 
        ICollectionView cvCollectionView = CollectionViewSource.GetDefaultView(this.Suivis);
        if (cvCollectionView == null)
            return;

        // filtrer ... exemple pour tests DI-2015-05105-0
        cvCollectionView.Filter = p_oObject => { return true; /* use your own filter */ };

        // page configuration
        int iMaxItemPerPage = 2;
        int iCurrentPage = 0;
        int iStartIndex = iCurrentPage * iMaxItemPerPage;

        // déterminer les objects "de la page"
        int iCurrentIndex = 0;
        HashSet<object> hsObjectsInPage = new HashSet<object>();
        foreach (object oObject in cvCollectionView)
        {
            // break if MaxItemCount is reached
            if (hsObjectsInPage.Count > iMaxItemPerPage)
                break;

            // add if StartIndex is reached
            if (iCurrentIndex >= iStartIndex)
                hsObjectsInPage.Add(oObject);

            // increment
            iCurrentIndex++;
        }

        // refilter
        cvCollectionView.Filter = p_oObject =>
        {
            return cvCollectionView.Contains(p_oObject) && hsObjectsInPage.Contains(p_oObject);
        };