Copy Items from a Generic List into multiple Generic Lists

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Sam Shrefler - 12 Oct 2007 16:22 GMT

I have two List<Order> and List<OrderDetails>

Order looks like this:
{
int orderID
List<OrderDetails> details
orderTotal
orderDate
...
}

I have a List that contains ALL OrderDetails and looks like this:
{
int orderID
Details details
...
}

What I'm looking to do process the second list so that i copy each
corresponding OrderDetail into the parent Order details.

What would be the best way to go about this?

Thanks

Sam

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Jon Skeet [C# MVP] - 12 Oct 2007 16:24 GMT

> I have two List<Order> and List<OrderDetails>
>
[quoted text clipped - 20 lines]
>
> What would be the best way to go about this?

I'd create a Dictionary<int,Order> so that you can get from the order
ID to the order quickly. Then just do something like:

foreach (OrderDetails details in listOfOrderDetails)
{
Order order = orders[details.orderID];
order.details.Add(details);
}

Jon

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Sam Shrefler - 12 Oct 2007 16:41 GMT

Jon:

Thanks.

Is there an easy way to convert between a List and a Dictionary?

My List is already populated through an automatic DataReader->List
generator and given to me as a List...

Thanks

Sam

> > I have two List<Order> and List<OrderDetails>
>
[quoted text clipped - 34 lines]
>
> - Show quoted text -

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Jon Skeet [C# MVP] - 12 Oct 2007 16:51 GMT

> Is there an easy way to convert between a List and a Dictionary?

foreach (Order order in orders)
{
orderDictionary[order.orderID] = order;
}

is probably about as easy as you can get. (It's slightly easier with
LINQ in C# 3, admittedly...)

Jon

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abieganski@gmail.com - 12 Oct 2007 17:04 GMT

> Is there an easy way to convert between a List and a Dictionary?
>
> My List is already populated through an automatic DataReader->List
> generator and given to me as a List...

This should work pretty well:

Dictionary<int, Order> orders = new Dictionary<int, Order>();
list.ForEach(delegate(Order o)
{
orders.Add(o.orderID, o);
});

Cheers,
Adam
___________________
ab
http://godevelop.blogspot.com

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Jon Skeet [C# MVP] - 12 Oct 2007 18:27 GMT

> > Is there an easy way to convert between a List and a Dictionary?
> >
[quoted text clipped - 8 lines]
> orders.Add(o.orderID, o);
> });

That will certainly work - but I think for situations as simple as
that, I'd usually use the normal foreach loop instead of the ForEach
method taking a delegate. Aside from anything else, introducing
captured variables can make life complicated in a hurry, and the
debugging is more "interesting" with the delegate version.

(In other cases where it brings a benefit, of course, it's a different
matter.)

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