[hibernate-issues] [Hibernate-JIRA] Created: (HHH-5212) Alter SQLFunction contract to be more flexible

[Steve Ebersole (JIRA)]

Alter SQLFunction contract to be more flexible
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                 Key: HHH-5212
                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-5212
             Project: Hibernate Core
          Issue Type: Improvement
          Components: core, query-criteria, query-hql
            Reporter: Steve Ebersole


The SQLFunction contract currently combines contextual information (render/getReturnType) and non-contextual (aka non-changing) information (hasArguments/hasParenthesesIfNoArguments).

An example I just ran into where separating these would have been nice is in HHH-5173.  Some dialects return the argument data type when applying the AVG() function.  That is problematic for INTEGER values because the decimal portion gets dropped.  On those databases one would need to CAST() the argument to get the correct behavior.  However, again, this is only necessary based on the argument type.  If the argument type is already a non-integer the cast is uneeded.

Proposal (as always name subject to change/suggestion):
{code}
interface SQLFunction {
    public boolean hasArguments();
    public boolean hasParenthesesIfNoArguments();

    public RenderingContext getRenderingContext(Type columnType, SessionFactoryImplementor factory);

    public static interface RenderingContext {
        public Type getReturnType();
        public String render(List args);
    }
}
{code}

I used SessionFactoryImplementor as the argument to getRenderingContext, but the current getReturnType accepts a Mapping.  Is there really ever a time when we call that method when we do not have a SessionFactory?  My usage search shows no usages of this method passing in a Configuration (which is the other Mapping implementor aside from SessionFactory).

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