You can do this:
using System.Collections.ObjectModel;
using System.Collections.Generic;
public class MyEntity
{
private IList<int> _numbers;
public ReadOnlyCollection<int> Numbers
{
get
{
return new ReadOnlyCollection<int>(_numbers);
}
}
}
List<T> has a method named AsReadOnly() that returns a
ReadOnlyCollection<T>, but from what little I know, when using lists
for your collections, the members you map to have to be declared as
IList<T> objects, not List<T> objects. It's not really a big deal
though, because in Reflector, the implementation of AsReadOnly() is:
public ReadOnlyCollection<T> AsReadOnly()
{
return new ReadOnlyCollection<T>(this);
}
So it's the same either way.
On Dec 21, 2:59 am, s_tristan <[email protected]> wrote:
> You can create a custom collection without IUserCollection as was
> written this:http://blog.benday.com/archive/2007/10/22/23164.aspx
>
> On 19 дек, 19:42, epitka <[email protected]> wrote:
>
> > I do like this better. Had to make small change to interceptor.
>
> > private IBag<Package> _packages;
> > [Relationship("packages", RelationshipType.Aggregation,
> > Cardinality.OneOrMore, inverseProperty = "project")]
> > public virtual IEnumerable<Package> packages
> > {
> > get
> > {
> > return _packages;
> > }
> > }
>
> > public virtual bool AddPackage(Package package, out List<string>
> > brokenRules)
> > {
> > PrePackageAdd(package, out brokenRules);
>
> > if (brokenRules.Count>0)
> > {
> > return false;
> > }
>
> > _packages.Add(package);
>
> > PostPackageAdd(package);
>
> > return true;
> > }
>
> > On Dec 19, 8:33 am, Daniel Fernandes <[email protected]>
> > wrote:
>
> > > How long is a piece of string ?
> > > If your project really needs you to develop such a collection and your
> > > consumers are aware of what's going on then I think it's fine.
> > > But as you said it, fully exposing a collection brings risks and it
> > > might be better to just revert to public AddXXX/RemoveXXX methods.
> > > I tend now to use IEnumerable because it's by its definition the items
> > > references are read-only.
>
> > > On Dec 19, 2:15 pm, epitka <[email protected]> wrote:
>
> > > > Well, I have developed one that does all of the houskeeping,
> > > > synchronize, raise events etc., but now looking at it, I am not sure
> > > > that is the best way, since the API is not really revealing what is
> > > > happening. I had to do this for the company I work(ed) for as they had
> > > > a system that had it's own higher level language that allowed direct
> > > > manipulation of collections. Now for example if you set a value in
> > > > collection through indexer and there is already item on that index, it
> > > > would remove item from the collection, synchronize if bi-directions,
> > > > raise remove events, that insert item and the same index, synch, and
> > > > raise add. That is a lot of work that happens that one might not be
> > > > aware of. Only piece that was not in place was vetoing change.
>
> > > > On Dec 19, 8:04 am, Daniel Fernandes <[email protected]>
> > > > wrote:
>
> > > > > Typical pattern is :
>
> > > > > IEnumerable<Foo> Foos {
> > > > > get { return _foos; }}
>
> > > > > bool AddFoo(Foo foo) {
> > > > > // business rules here and references management (bi-directional
> > > > > association, orphan children, multiplicity etc..)}
>
> > > > > bool RemoveFoo(Foo foo) {
> > > > > // business rules here and references management (bi-directional,
> > > > > orphan children, multiplicity, etc..)
>
> > > > > }
>
> > > > > There must be around some good IList`1 implementations giving you
> > > > > callbacks for when an object is added/removed as in Linq2Sql (can't
> > > > > remember the class name).
>
> > > > > Daniel
>
> > > > > On Dec 19, 1:06 pm, epitka <[email protected]> wrote:
>
> > > > > > That is what I was after, as I've seen people providing Add/Remove
> > > > > > methods and also exposing it as IList. I guess this post nails it
> > > > > > down
> > > > > > why.
>
> > > > > >http://tomas.oo-systemutvecklare.se/articles/encapsulation.php
>
> > > > > > On Dec 18, 11:12 pm, "Greg Young" <[email protected]> wrote:
>
> > > > > > > I don't even expose it as a collection only as an IEnumerable
>
> > > > > > > Why do you as a client care how I store it internally?
>
> > > > > > > Cheers,
>
> > > > > > > Greg
>
> > > > > > > On Thu, Dec 18, 2008 at 7:49 PM, epitka <[email protected]>
> > > > > > > wrote:
>
> > > > > > > > But how do you protect your collection from being changed;
> > > > > > > > exposing it
> > > > > > > > as read-only? But that is not intuitive, if client does not
> > > > > > > > know that
> > > > > > > > AddPerson is to be used you would get exception.
> > > > > > > > Why is #2 not viable?
>
> > > > > > > > On Dec 18, 9:29 pm, "Greg Young" <[email protected]>
> > > > > > > > wrote:
> > > > > > > >> 1. don't let collection be modified directly but use
> > > > > > > >> Add/remove and
> > > > > > > >> enforce rule there
>
> > > > > > > >> Have the aggregate root enforce the validation.
>
> > > > > > > >> Cheers,
>
> > > > > > > >> Greg
>
> > > > > > > >> On Thu, Dec 18, 2008 at 7:25 PM, epitka
> > > > > > > >> <[email protected]> wrote:
>
> > > > > > > >> > This is probably more a DDD question then NH. Let say you
> > > > > > > >> > have
> > > > > > > >> > observable collections that raise events before collection
> > > > > > > >> > gets
> > > > > > > >> > changed and after. Let's say you have a rule that only
> > > > > > > >> > person's over
> > > > > > > >> > 21 can be added to the collection. How would you handle this
> > > > > > > >> > rule:
> > > > > > > >> > 1. don't let collection be modified directly but use
> > > > > > > >> > Add/remove and
> > > > > > > >> > enforce rule there
> > > > > > > >> > 2. create delegate that will check rule in OnChanging step
> > > > > > > >> > and veto
> > > > > > > >> > change
> > > > > > > >> > 3. allow person to be added and run validate before
> > > > > > > >> > persisting entity
> > > > > > > >> > using NH events, basically allow entity to get into invalid
> > > > > > > >> > state
> > > > > > > >> > 4. manually invoke validation before commiting changes.
> > > > > > > >> > 5. something else ?
>
> > > > > > > >> --
> > > > > > > >> It is the mark of an educated mind to be able to entertain a
> > > > > > > >> thought
> > > > > > > >> without accepting it.
>
> > > > > > > --
> > > > > > > It is the mark of an educated mind to be able to entertain a
> > > > > > > thought
> > > > > > > without accepting it.- Скрыть цитируемый текст -
>
> > - Показать цитируемый текст -
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