Calling a custom method from a datagridview column expression

Question

Howdy

using c#, vs2008 winforms

I have a datagridview that i am programtically binding to a binding source, that is bound to a dataset with 1 table.

After filling the dataset using the sqlAdaptor, i want to add a new column to the dataset, and in the new column populate it with a result derived from a call to a custom method in the form.

Code Eg is bellow but i get a "Expression contains undefined function call this.Test()

Is it allowed to call methods as such in the expression of the column

thanks in advance for any help cheers

this.dsProdOrdLst1.ProdOrder.Columns.Add("sOrderType", typeof(string), 
    "this.Test(order_type)"); // order_type is another column in the dataset

elsewhere in the form class is the method

public int Test(int orderType)
{
    return 10; //return a test value
}

Answer 1

AFAIK, these expressions (known as ADO.NET expressions) have no way of calling any kind of user defined functions. It should however by trivial to manually populate the new column:

this.dsProdOrdLst1.ProdOrder.Columns.Add("sOrderType", typeof(string));

foreach (DataRow row in dsProdOrdLst1.ProdOrder.Rows)
{
    row["sOrderType"] = Test((int) row["order_type"]);
}

Alternatively, you might be able to implement your entire function in an ADO.NET expression, but you really only want to do this for very simple functions, as otherwise it will be a mess:

IIF(order_type = 0, 'Mail', IIF(order_type = 1, 'Phone', 'Online'))

The documentation of DataColumn.Expression has a list of supported functions (scroll pretty far down to find it).