[nhibernate-issues] [NHJIRA] Commented: (NH-2658) Linq provider overcaching HQL

[Daniel G. (JIRA) <nh...@gm...>]

    [ http://216.121.112.228/browse/NH-2658?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=20929#action_20929 ] 

Daniel Guenter commented on NH-2658:
------------------------------------

I have a patch (HG) which solves this issue.

https://bitbucket.org/nicaog/nhibernate-patches/changeset/8ea3eb358e61

However it does introduce a new concept into the system. IHqlGenerator(s) are allowed to participate in the initial building of the expression tree and key through the use of a SpecialMemberVisitor and a new interface method called Visit.  This allows for expression replacing and parameter manipulation before the expression key is finalized. 

This solution may be a bit more intrusive than I had hoped it would be. However it does allow for more advanced and intelligent hql generators.

> Linq provider overcaching HQL
> -----------------------------
>
>                 Key: NH-2658
>                 URL: http://216.121.112.228/browse/NH-2658
>             Project:  NHibernate
>          Issue Type: Bug
>          Components: Linq Provider
>    Affects Versions: 3.1.0
>            Reporter: Daniel Guenter
>            Priority: Major
>         Attachments: NH2658_failing_test_case.patch
>
>
> The linq provider caches a query assuming that ALL constants will be turned into HQL parameters. Sometimes this is not the case. A linq extension that selects a concrete entity property based on a constant value will never pass that value into HQL.
> This is also a blocking issue in getting Linq to work with dynamic-components.  The string value passed into the dictionary (dict["key"] == x) cannot be passed to HQL as a parameter as it is directly evaluating a property name. Thus the first query will work but subsequent queries will be wrong and will reuse the column/property name of the first cached query. 

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