How do I bind a ComboBox so the displaymember is concat of 2 fields of source datatable?

Question

I'd like to bind a ComboBox to a DataTable (I cannot alter its original schema)

cbo.DataSource = tbldata;
cbo.DataTextField = "Name";
cbo.DataValueField = "GUID";
cbo.DataBind();

I want the ComboBox show tbldata.Name + tbldata.Surname.

Of course adding the new name+surname as a field to the tbldata just before binding is possible, but I am hoping for a more elegant solution along the lines of (pseudocode)

cbo.DataTextField = "Name";
cbo.DataTextField += "Surname";

Solution 1

The calculated column solution is probably the best one. But if you can't alter the data table's schema to add that, you can loop through the table and populate a new collection that will serve as the data source.

var dict = new Dictionary<Guid, string>();
foreach (DataRow row in dt.Rows)
{
    dict.Add(row["GUID"], row["Name"] + " " + row["Surname"]);
}
cbo.DataSource = dict;
cbo.DataTextField = "Value";
cbo.DataValueField = "Key";
cbo.DataBind();

Obviously this isn't as performant as binding directly to the DataTable but I wouldn't worry about that unless the table has thousands of rows.

Solution 2

The easiest way is to create a new calculated column in the DataTable, using the Expression property :

tbldata.Columns.Add("FullName", typeof(string), "Name + ' ' + Surname");
...
cbo.DataTextField = "FullName";

Solution 3

I would create a property on your data object then map that to the DataTextField

Data Object

public string FullName
{
  get { return Name + " " + Surname; }
}

Code-behind

cbo.DataSource = tbldata;
cbo.DataTextField = "FullName";
cbo.DataValueField = "GUID";
cbo.DataBind();

Solution 4

Or implement 'Format' event like this:

DataRow r = ((DataRowView)e.ListItem).Row;
e.Value = r[ "FirstName" ] + " - " + r[ "LastName" ];

Solution 5

Have a property in your class that is the concat of Name and Surname. And bind the DataTextField to this property.

In case you are binding it to a DataTable, you can add a new column to the DataTable whose values are concat of Name and Surname and bind it to the combo.

View more solutions

Comments

[AlexDrenea]

i agree, can't think of another way

[TheTXI]

I like this a lot better than the suggestions people keep making about modifying the data object and creating a new property.

[callisto]

Since this is a simple one-use only, using a class as a base for this is overkill.

[Konstantinos Chertouras]

Most useful ! Thanks.

[TangMonk]

Where is the Format event?

[jlear]

@TangMonk, the Format event is in the ComboBox class. See here: ComboBox