Add column to data table in

Hi, because of some complexity in my project, I am using for a part of my robot (Invoke Code).

With this line, I want to add a column to a data table:
out_dt_TruckAssembling.Columns.Add(“testcol”, GetType(Integer))

out_dt_TruckAssembling is a data table given as an ‘Out’ argument for Invoke Code.

But at runtime, it gives this error:

Am I wrong in use of the argument?


Can you try to add the following at the beginning of the code?

out_dt_TruckAssembling = New DataTable()


we can do the same within an Assign Activity and avoid the black box code activity

myCol = YourOriginDatTableVar.Columns.Add(“testcol”, GetType(Integer))

otherwise ensure that out_dt_TruckAssembling is initialized with a new DataTable() within the invoke code

We can also use Invoke Method for adding columns:

DataTable.Columns (“ColumnName”)) MethodName (SetOrdinal)

Same thing you can do it in your Vb code as well: to add a column

This does not work.
But I’ve found a workaround after your suggestion.

  1. Dim dt as New Datatable
  2. Do some things with dt (add columns etc…)
  3. out_dt_TruckAssembling = dt

After that, the argument is loaded in variable dt_TruckAssembling.

For information: imo, the code is to complex to do it all with UiPath activities. Coding it in makes it more clear.

It means out_dt_TruckAssembling hasn’t been initialized. It’s “nothing”


I think we can directly create instance for out_dt_TruckAssembling as the following sample. Can you try this? (2.5 KB)


You could have initialized the datatable as well, New System.Data.Datatable.


But as mentioned in my first question, I need do program it in Invoke code. It is really dynamic.

Thank you, Yoichi. It works now.

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