[nhibernate-issues] [NHJIRA] Updated: (NH-2735) Allow query on .id special accessor on <any> mappings via Linq

[Fabio M. (JIRA) <nh...@gm...>]

     [ http://216.121.112.228/browse/NH-2735?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Fabio Maulo updated NH-2735:
----------------------------

    Component/s:     (was: Core)
                 Linq Provider

> Allow query on .id special accessor on <any> mappings via Linq
> --------------------------------------------------------------
>
>                 Key: NH-2735
>                 URL: http://216.121.112.228/browse/NH-2735
>             Project:  NHibernate
>          Issue Type: Improvement
>          Components: Linq Provider
>    Affects Versions: 3.2.0Beta1
>            Reporter: Andrei Alecu
>
> Querying a property defined with an <any> mapping by its id needs to use the special .class and .id properties defined by HQL.
> Not having a way to access .id makes it impossible to translate queries such as the following to Linq:
>     from ToyBox t where t.Shape.class = Square and t.Shape.id = 1 (note that there's currently a bug with .class at NH-2734)
> Note that accessing the identifier property mapped as .Id (non lowercase) does not work, the HQL query parser complains that there's an access to an unmapped property .Id.
> My current workaround is to define this extension method as a custom linq generator:
>     public class ImplicitIdGenerator : BaseHqlGeneratorForMethod
>     {
>         public ImplicitIdGenerator()
>         {
>             this.SupportedMethods = new[] { ReflectionHelper.GetMethodDefinition<object>(x => x.ImplicitId()) };
>         }
>         public override HqlTreeNode BuildHql(
>             MethodInfo method,
>             Expression targetObject,
>             ReadOnlyCollection<Expression> arguments,
>             HqlTreeBuilder treeBuilder,
>             IHqlExpressionVisitor visitor)
>         {
>             return treeBuilder.Dot(visitor.Visit(arguments[0]).AsExpression(), treeBuilder.Ident("id"));
>         }
>     }
>     public static class NhibernateLinqExtensions
>     {
>         public static object ImplicitId(this object what)
>         {
>             throw new NotImplementedException("Used by NHibernate linq with <any> mappings.");
>         }
>     }
> I believe the special .id property may also be used in other circumstances when the name of the property used for the identifier is not known.
> I'm not sure if this is the most elegant implementation, but this code lets you do this:
> var results = session.Query<ToyBox>().Where(x=> /* class constraint, see NH-2328 */ && x.Shape.ImplicitId() == 1);

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