[hibernate-dev] Stored procedure support
Steve Ebersole
steve at hibernate.org
Fri Nov 16 15:38:26 EST 2012
Again I am not so sure that registerInParameter is any more readable
than registerParameter passed ParameterMode.IN. Registering a
parameter is registering a parameter is registering a parameter to
para-quote Ms Stein. To me the one thing that would make sense to
split them out that way is what I think you are thinking as well in
your last bit. That is, if we were to do:
interface RegisteredParameter<T> {
public Class<T> getJavaType();
public ParameterMode getMode();
}
interface BindableRegisteredParameter<T> extends RegisteredParameter<T> {
public void bind(T value);
}
Now the "split" methods make more sense:
public <T> BindableRegisteredParameter<T> registerInParameter(int
position, Class<T> type);
public <T> BindableRegisteredParameter<T> registerInParameter(String
name, Class<T> type);
public <T> BindableRegisteredParameter<T> registerInOutParameter(int
position, Class<T> type);
public <T> BindableRegisteredParameter<T>
registerInOutParameter(String name, Class<T> type);
public <T> RegisteredParameter<T> registerOutParameter(int position,
Class<T> type);
public <T> RegisteredParameter<T> registerOutParameter(String name,
Class<T> type);
On Fri, Nov 16, 2012 at 2:28 PM, Gunnar Morling <gunnar at hibernate.org> wrote:
> IMO registerInParameter(String,Class) et al. read better than
> registerParameter(int,Class,ParameterMode), while the latter might be a bit
> simpler to use when writing the code. As code is more read than written,
> optimizing the read use case might be the better option. But I agree that
> six methods compared to two is quite a difference.
>
> Using different types for the different kinds of parameters would also avoid
> the possibility of reading values from an IN parameter.
>
>
>
> 2012/11/16 Steve Ebersole <steve at hibernate.org>
>>
>> I can definitely see a benefit to your registerOutParameter over
>> registerParameter if we wanted to return specific types. But aside
>> from that, I am not so sure that having to know 3 different sets of
>> methods to register parameters:
>>
>> registerInParameter(int,Class)
>> registerInParameter(String,Class)
>> registerInOutParameter(int,Class)
>> registerInOutParameter(String,Class)
>> registerOutParameter(int,Class)
>> registerOutParameter(String,Class)
>>
>> is better than one set:
>>
>> registerParameter(int,Class,ParameterMode)
>> registerParameter(String,Class,ParameterMode)
>>
>> Do you really think that is easier for a user?
>>
>> On Fri, Nov 16, 2012 at 12:52 PM, Gunnar Morling <gunnar at hibernate.org>
>> wrote:
>> > Hi,
>> >
>> > FWIW, I'd prefer option #2 due to its type-safety. In #3 it's as you say
>> > challenging to control when extract() can be invoked.
>> >
>> > Maybe you could offer dedicated methods for the different parameter
>> > modes,
>> > making client code a bit shorter:
>> >
>> > RegisteredParameter<Long> p1Param =
>> > call.registerOutParameter( "p1", Long.class );
>> >
>> > I tend towards that pattern if the number of possible enum values is
>> > small,
>> > as it should be the case here.
>> >
>> > --Gunnar
>> >
>> >
>> >
>> > 2012/11/16 Steve Ebersole <steve at hibernate.org>
>> >
>> >> I thought I had written about this before to the list, but maybe not.
>> >> Anyway, I added much enhanced support for calling database functions
>> >> and
>> >> procedures to master. But this is just my initial swag and as far as I
>> >> know my eyes are the only ones that have seen it. So I wanted to get
>> >> some feedback. Feel free to give feedback on any/all aspects of that
>> >> API, but there was one aspect in particular I was really wanting
>> >> feedback: parameters. The concept of parameters, much like in queries,
>> >> is split into 2 parts: declaration and usage.
>> >>
>> >> The initial impetus for this was the JPA 2.1 feature for supporting
>> >> procedure calls. But I went a little different direction in our
>> >> "native" support for this, the main difference being modeling the
>> >> outputs as a separate thing from the call itself. I really like our
>> >> API
>> >> there better.
>> >>
>> >> The declaration of the call is modeled as
>> >> org.hibernate.StoredProcedureCall (although I am thinking of moving
>> >> away
>> >> from "StoredProcedure" as the name base here since functions are
>> >> supported as well; better name suggestions welcome). The outputs of
>> >> the
>> >> call execution is org.hibernate.StoredProcedureOutputs.
>> >>
>> >> To create a StoredProcedureCall, one simply calls one of the overloaded
>> >> Session.createStoredProcedureCall methods passing in either (a) the
>> >> func/proc name, (b) the func/proc name and any entity class(es) to map
>> >> the results back to, (c) the func/proc name and any result set mapping
>> >> name(s) to apply to the results.
>> >>
>> >> From there, parameters are declared/registered through the overloaded
>> >> StoredProcedureCall#registerStoredProcedureParameter methods. Again,
>> >> in
>> >> retrospect not liking that name; should be declareParameter or
>> >> registerParameter imo. Anyway, parameters can be treated as either
>> >> positional or named. Named here has a little bit different meaning
>> >> though, intending to name the arguments in the procedure/function
>> >> definition. This is a feature defined by JDBC 3, although as I
>> >> understand it not all drivers support it (aka, it can lead to
>> >> SQLFeatureNotSupportedException). We can even know this a priori via
>> >> DatabaseMetaData.html#supportsNamedParameters() to give better (and
>> >> earlier!) exceptions.
>> >>
>> >> Anyway, currently registerStoredProcedureParameter returns back
>> >> StoredProcedureCall for method chaining. We'll come back to that in a
>> >> second...
>> >>
>> >> After parameters are registered, the values for IN and INOUT style
>> >> parameters must be set/bound. Currently this is untyped because of the
>> >> fact that registration does not return any "memento" with the typing
>> >> information (the Java type is passed to the register method). After
>> >> execution, the values from all INOUT and OUT parameters can be
>> >> extracted, but again those extractions are untyped for the same reason.
>> >> Which leads me to question whether we want to consider handling
>> >> parameter values (whether in or out) in a typed manner is important.
>> >> As
>> >> an example, currently to extract an OUT parameter value you'd have:
>> >>
>> >> StoredProcedureCall call =
>> >> session.createStoredProcedureCall("my_proc");
>> >>
>> >> call.registerStoredProcedureParameter("p1",Long.class,ParameterMode.OUT);
>> >> //maybe some other stuff...
>> >> StoredProcedureOutputs outputs = call.getOutputs();
>> >> Long p1 = (Long) outputs.getOutputParameterValue("p1");
>> >>
>> >> The alternative would be something like defining a typed
>> >> RegisteredParameter contract:
>> >>
>> >> interface RegisteredParameter<T> {
>> >> public Class<T> getParameterType();
>> >> public ParameterMode getMode();
>> >> }
>> >>
>> >> and then:
>> >>
>> >> StoredProcedureCall call =
>> >> session.createStoredProcedureCall("my_proc");
>> >> RegisteredParameter<Long> p1Param = call.registerParameter(
>> >> "p1",
>> >> Long.class,
>> >> ParameterMode.OUT
>> >> );
>> >> //maybe some other stuff...
>> >> StoredProcedureOutputs outputs = call.getOutputs();
>> >> Long p1 = outputs.getOutputParameterValue( p1Param );
>> >>
>> >>
>> >> Or maybe even:
>> >>
>> >> interface RegisteredParameter<T> {
>> >> public Class<T> getParameterType();
>> >> public ParameterMode getMode();
>> >>
>> >> public void bind(T value);
>> >> public T extract();
>> >> }
>> >>
>> >> StoredProcedureCall call =
>> >> session.createStoredProcedureCall("my_proc");
>> >> RegisteredParameter<Long> p1Param = call.registerParameter(
>> >> "p1",
>> >> Long.class,
>> >> ParameterMode.OUT
>> >> );
>> >> //maybe some other stuff...
>> >> StoredProcedureOutputs outputs = call.getOutputs();
>> >> Long p1 = p1Param.extract();
>> >>
>> >> The problem with this last one is managing when that 'extract' can be
>> >> called...
>> >>
>> >>
>> >> Anyway, thoughts?
>> >>
>> >> --
>> >> steve at hibernate.org
>> >> http://hibernate.org
>> >> _______________________________________________
>> >> hibernate-dev mailing list
>> >> hibernate-dev at lists.jboss.org
>> >> https://lists.jboss.org/mailman/listinfo/hibernate-dev
>> >>
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>
>
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