数据源是无效类型。它必须是IListSource，IEnumerable或IDataSource

Question

Data source is an invalid type. It must be either an IListSource, IEnumerable, or IDataSource. The error is displayed when I bind the grid view

var list = dal.GetEmployeebyName(name);
GridViewEmployee.DataSource = list;
GridViewEmployee.DataBind();

i have the query

public EmployeeInfo GetEmployeebyName(String name)
{
    using (var context = new HRMSEntities())
    {
        return context.EmployeeInfo.FirstOrDefault(e => e.FName == name);
    }
}

Answer 1

You are returning a single object from GetEmployeebyName method and binding that to the GridViewEmployee, thats why it is giving error.

You can change it like

var empInfo = dal.GetEmployeebyName(name);
var list = new List<EmployeeInfo>{empInfo};

//or you can do this 
//var list = new List<EmployeeInfo>();
//list.Add(empInfo);

GridViewEmployee.DataSource = list;
GridViewEmployee.DataBind();

DataSource must be a type of collection as the exception is stating ( It must be either an IListSource, IEnumerable, or IDataSource)

Answer 2

Could the above not be shortend to..

var empInfo = dal.GetEmployeebyName(name);

GridViewEmployee.DataSource = empInfo.ToList();
GridViewEmployee.DataBind();

Answer 3

In my testing page I make us of the following piece of code to display a list of different objects or just a single object in the same gridview.

   var data = bl.getAirlines();
   // If single object returned cast to List
   // Note that could be already a list of 1 item though!
    if (data.Count == 1)
    {
        var list = new List<object> { data };               
        GridView1.DataSource = list;
    }
    else
     // Bind to list of items returned
        GridView1.DataSource = data;

    GridView1.DataBind();

Hope it helps! It works for me :)