CODEWITHSUNDEEP
c#datagridview
Xavier Peña
Xavier Peña

Reputation: 7899

DataGridView in c#: combining Properties as Columns with elements of a List as Columns

I have been trying to wrap my mind around this problem for way too long... I am really out of ideas.

The explanation of what I need to achieve is pretty simple. This is my object, which contains a list: 

class MyObject
{
    public string property1 { get; set; }
    public string property2 { get; set; }
    public List<string> list { get; set; }
}

Now, I need the columns of the DataGridView to look like this:

[property1] | [property2] | [list_element1] | ... | [list_elementN]

The data binding should be as simple as possible (my real object has way more than two non-list properties).

I have even tried Reflection to create a dynamic object with list_element1, ... , list_elementN as properties. I kind of works, but there are certain issues with creating new rows of the DataGridView so I abandoned this path.

Any ideas of what could my best option be?

Upvotes: 0

Views: 380

Answers (1)

stefankmitph
stefankmitph

Reputation: 3306

I think I found a way for you to do it... (and I want to make clear that my code indeed is very error prone but I just want to show that there's a silver lining, so please don't pin me down on this)

Assuming you have your datasource like this:

List<MyObject> dataSource = new List<MyObject>
{
    new MyObject
    {
        ID = 1,
        Name = "Row1",
        List = new List<string>() {"item1", "item2", "item3"}
    },
    new MyObject
    {
        ID = 2,
        Name = "Row2",
        List = new List<string>() {"item4", "item5", "item6"}
    },
    new MyObject
    {
        ID = 3,
        Name = "Row3",
        List = new List<string>() {"item7", "item8", "item9"}
    }
};

You can go for a dynamic datasource created out of your existing MyObject. (I took ExpandoObject so I can add properties to it dynamically)

List<dynamic> dynamicSource = new List<dynamic>();
foreach (var data in dataSource)
{
    dynamic o = new ExpandoObject();
    // assigning properties we already know
    o.ID = data.ID;
    o.Name = data.Name;

    int idx = 0; // just a counter. you could also do this with a for-loop of course
    foreach (var item in data.List)
    {
        var dict = o as IDictionary<string, Object>; // cast expando object just to get the properties as key and value pairs in a dictionary
        dict.Add("ItemNr" + idx, item);
        idx++;
    }
    dynamicSource.Add(o);
}

Now there's a little extension method I found here which becomes very handy at this point

    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;
    }

Now we can add the datasource to our DataGridView like this:

var dataTable = Extensions.ToDataTable(dynamicSource);
dataGridView1.DataSource = dataTable;

It should be assigned correctly now. What I've tested, adding rows shouldn't be a problem now.

If you want to get back your DataSource you have to take following little method:

private List<MyObject> ConvertBackToObject(DataTable dataTable)
    {
        // basically the same procedure as assigning

        List<MyObject> listMyDataSource = new List<MyObject>();
        foreach (DataRow row in dataTable.Rows)
        {
            MyObject myObject = new MyObject
            {
                ID = Convert.ToInt16(row["ID"]),
                Name = row["Name"].ToString(),
                List = new List<string>()
            };

            foreach (var column in dataTable.Columns.Cast<DataColumn>().Where(col => col.ColumnName.StartsWith("ItemNr")))
            {
                myObject.List.Add(row[column].ToString());
            }

            listMyDataSource.Add(myObject);
        }

        return listMyDataSource;
    }

which leads us to this (actually getting the datasource):

DataTable dataTable = dataGridView1.DataSource as DataTable;
// do some null checking here
List<MyObject> myObjects = ConvertBackToObject(dataTable);

This should give you the updated List of your MyObject (which you now can use for inserting data to the database).

Hope it is clear in some way and helped.

Upvotes: 1

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