Concatenating 2 objects into a dictionary value - linq

Question

I have the following code, that creates a dictionary:
branches.ToDictionary(row => row.Field<object>(1), row => row.Field<object>(3)).ToList();
I want to create the dictionary value as row.Field<object>(3) + row.Field<object>(4). I think I'm looking for some kind of a concat method, but none seem to be available. Will I have to loop through each element individually?

Answer 1

If the types of row.Field<object>(3) and row.Field<object>(4) are string, then read them as strings and + them together (or perhaps use string.Format or string.Concat):
branches.ToDictionary(
row => row.Field<object>(1),
row => row.Field<string>(3) + row.Field<string>(4)
).ToList();
If they are really object or two types that you just want paired together, you can add them as a tuple, or preferably create a class to hold them. For example:
public class IntAndString //Choose a better name than this!
{
public int IntValue { get; set; }
public string StringValue { get; set; }
}
And then project the values into the class:
branches.ToDictionary(
row => row.Field<object>(1),
row => new IntAndString
{
IntValue = row.Field<int>(3),
StringValue = row.Field<string>(4)
}
).ToList();

Answer 2

Just concat them, but if these are string-columns use Field<string>(preferred) or ToString:
branches.ToDictionary(
row => row.Field<object>(1),
row => row.Field<string>(3) + row.Field<string>(4))
.ToList();
In general use the correct type instead always object.
Another way if you only have objects is to use String.Concat:
branches.ToDictionary(
row => row.Field<object>(1),
row => String.Concat(row.Field<object>(3), row.Field<object>(4)))
.ToList();