Binding a GridView to a Dynamic or ExpandoObject o

问题:

I'm using Rob Conery's Massive ORM, and I haven't been able to bind the resulting ExpandoObject to a GridView.

I did find another Stackoverflow question that suggests using a framework called impromptu, but I'm not sure if that would work for this. If you know it does, please provide a code sample to actually convert an ExpandoObject to something that the GridView control can bind to.

Worst case scenario, has anyone implemented an additional method (that can be shared) for Massive to convert the resulting ExpandoObject to a POCO?

any help is greatly appreciated. Thanks.

回答1:

Since you can't bind to an ExpandoObject, you can convert the data into a DataTable. This extension method will do that for you. I might submit this for inclusion to Massive.

/// <summary>
/// Extension method to convert dynamic data to a DataTable. Useful for databinding.
/// </summary>
/// <param name="items"></param>
/// <returns>A DataTable with the copied dynamic data.</returns>
public static DataTable ToDataTable(this IEnumerable<dynamic> items) {
    var data = items.ToArray();
    if (data.Count() == 0) return null;

    var dt = new DataTable();
    foreach(var key in ((IDictionary<string, object>)data[0]).Keys) {
        dt.Columns.Add(key);
    }
    foreach (var d in data) {
        dt.Rows.Add(((IDictionary<string, object>)d).Values.ToArray());
    }
    return dt;
}

回答2:

If we are talking GridView (meaning not WPF) then impromptu can proxy an expando to a poco given an interface. Say we have a list of expando's you can convert them to poco's:

IEnumerable<IMyInterface> listOfPocos
       = Impropmtu.AllActLike<IMyInterface>(listOfExpandos, typeof(INotifyPropertyChanged));

回答3:

I adapted Brian's accepted answer to be a little more concise and LINQ-y:

public static DataTable ToDataTable(this IEnumerable<dynamic> items)
{
    var list = items.Cast<IDictionary<string, object>>().ToList();
    if(!list.Any()) return null;

    var table = new DataTable();
    list.First().Keys.Each(x => table.Columns.Add(x));
    list.Each(x => x.Values.Each(y => table.Rows.Add(y)));

    return table;
}

(This assumes you've defined an IEnumerable.Each extension, which every codebase I've worked on has had).

回答4:

Ok, apparently as of now, you just can't bind a GridView control to an ExpandoObject instance. I had to use reflection to convert the ExpandoObject to a POCO class.

回答5:

I came to this thread after researching on the same topic, I found no solution but constructed my own as I desperately needed this one. So here is my solution without going POCO that really works.

// Fill "list" with your dynamic objects.

// cast a dynamic object to dictionary so we get the properties from it.
var props = list[0] as IDictionary<string, object>;

// create a datatable 
var table = new System.Data.DataTable();
    foreach (var c in props.Keys)
        table.Columns.Add(new DataColumn(c));

foreach (var o in list)
{
    var row = table.NewRow();
    var op =  o as IDictionary<string, object>;
    foreach (var p in op.Keys)
    {
        row[p] = op[p];
    }
    table.Rows.Add(row);
}

And simply bind this table to your grid!

I tested it and it worked for me.

回答6:

adapting from Ben's answer

 public static DataTable ToDataTable(this IEnumerable<dynamic> items)
    {
        if (!items.Any()) return null;

        var table = new DataTable();
        bool isFirst = true;

        items.Cast<IDictionary<string, object>>().ToList().ForEach(x =>
        {
            if (isFirst) 
              {
                x.Keys.Select(y => table.Columns.Add(y)).ToList();
                isFirst = false;
              }
            table.Rows.Add(x.Values.ToArray());
        });

        return table;
    }