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# Copying an element from List (of T0

I have a dataset that is defined as List (of DC_LocationProfile)

When I get this dataset back I want to step through it and when I find the element that I want I want to copy it to List (Of NewLocations)

Can I copy from one List (of T) to another List (of T)

For Each element In DCLoc -- This is a List (OF T)
If element.ProfileQuestionID = "126" Then
*** I want to copy one element from DCLoc to another List (of T)**
End If

Next

Can I copy from one List (of T) to another List (of T).  When I try to copy to another List (of T) I am getting a cannot convert to 1-dimensional array error.

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sherbug1015
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1 Solution

Middle School Assistant TeacherCommented:
Sure...but how do you convert from a DC_LocationProfile to a NewLocations?
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Author Commented:
I have tried

If....Then
DCLoc.CopyTo(NewLocation)

This is where I am getting the converting to 1-dimensional array error.
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Middle School Assistant TeacherCommented:

*But, you've said that the first list contains type 'DC_LocationProfile' while the second list contains type 'NewLocations'.

...so you'd need to convert one type to the other somehow.
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Author Commented:
Any idea of how to convert from one type to the other.  I need the second type because I only want one element in there.  The original type I must leave intact.

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PresidentCommented:
Without the real declarations, it's always hard to tell, but let's start for the following. Not counting that you have NewLocation (singular) and NewLocations (plural). Is it a typo or are those 2 different classes? It is always better to copy and paste real code than giving code that "shows the concept". Code that shows the concept is almost never right :-)

Here are a few pointers to guide you.

From what you say, one list is a List (of DC_LocationProfile) while the other is a List (Of NewLocations). You won't be able to copy an element from one list to the other, because they are not of the same type.

DCLoc.CopyTo copies the whole list, not a single element. If you want to copy one element, do not use CopyTo. Get the element and Add it to the other list, something such as: List2.Add(List1(23)). The T in each list should be or the same type for this to work, unless you have some way to convert between the types.
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Middle School Assistant TeacherCommented:
What do the two types have in common?...we'd need to see those classes if you want a better answer.
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Author Commented:
What I am trying to do is create a unit test that has only one location in it.  I must first call the method that fills the List (of  DC_LocationProfile).  There are 106 records in this List.  Now that I have the List I want to just pull out one element and put it into another List (of DC_LocationsNew) so that I can pass that list to ProcessProfile to get a return value back.   testmethod.txt ProcessProfile.txt ProcessProfile.txt CopyToDataType.txt CopyFromDataType.txt
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PresidentCommented:
If you want a unit test to test for only one location, why pass the parameter as a list? Why not pass only the one object?

Then, as far as I can see, you do not seem to make any modification to the object in ProcessProfile. Why pass a copy? Why not pass only a reference. That would make things a lot easier, because you would not have to write a copy method.
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Author Commented:
OK.  If you were trying to pull one element out of List(Of T) and pass it as one object, then how would you do it.
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PresidentCommented:
Forget part of the last one, while revising your code, I grasped a few things I had not seen the last time. I understand that ProcessProfile is not always called with a single element.

But the following still holds if I am not misled: you do not seem to make any modification to the object in ProcessProfile. Why pass a copy? Why not pass only a reference.

In textmethod.txt, simply replace your ****Here I want to copy this one element to DC_LocationsNew (DCLoc1) by DLoc1.Add(element).

Sometimes, specially when you work on somebody else code, the obvious does not jump at your face.
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Author Commented:
I have already tried that.  I get an error that one type cannot be converted to another.

I found another way around this.

Thanks anyway.
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Middle School Assistant TeacherCommented:
"I get an error that one type cannot be converted to another. "

Well, yeah...we tried to get you to post your data type declarations so we could help you with that!
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Author Commented:
Idle Mind --- I did post my data type declarations.
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Middle School Assistant TeacherCommented:
I see that now...somehow I missed that post.
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