CODEWITHSUNDEEP
c#generics
Sanjeewa
Sanjeewa

Reputation: 83

2 Generic list assignment

if class type list is there named 

Collection<PurchaseOrderDetail> poDetails = new Collection<PurchaseOrderDetail>();

and another list with same type is there named _poH.PODetail

why _poH.PODetail = poDetails.ToList(); generates an error

Cannot implicitly convert type 'System.Collections.Generic.List' to 'System.Collections.ObjectModel.Collection'

what is the solution for this, any explanation please.

All the reason behind the question is 

_poH.PODetail = poDetails;

made poDetails.RemoveAt(Convert.ToInt32(e.RowIndex)); updates as well so I was searching for some thing like _poH.PODetail = poDetails.ToCollection();

Upvotes: 0

Views: 115

Answers (2)

Crono
Crono

Reputation: 10478

The short answer is simply that the ToList<T> extension returns an instance of List<T> class which, although similar, is not the same type as Collection<T>.

Basically this doesn't work for the same reasons you cannot set a string value to an integer variable.

One thing you can do though, is initializing the content of a new collection instance with an IList<T> instance. Therefore, the following should give you exactly what you want:

_poH.PODetail = new Collection(poDetails.ToList());

Also, as poke suggested, you might also want to assign the PODetail property with the poDetails variable itself.

_poH.PODetail = poDetails;

However, you must remember that Collection<T> is a reference type. This means that the objects in your collection won't be "copied" inside _poH.PODetail; instead, both poDetails and _poH.PODetail will be pointing to the exact same collection. Any changes done to one collection will automatically be reflected on the other.

Upvotes: 0

poke
poke

Reputation: 387547

According to the error message, _poH.PODetail is of type Collection, so assigning a list to it doesn’t work. But since poDetails is a collection itself, you can just assign it directly:

poH.PODetail = poDetails;

So you don’t actually need to call ToList() on it to convert it to a list.

There is no ToCollection method you could call on enumerables, but you could use the Collection constructor that takes a list to make it wrap that list and create a readonly collection:

new Collection(poDetails.ToList());

Upvotes: 1

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