Le vendredi 23 janvier 2015 04:40:04 UTC+1, Noel Grandin a écrit :
>
> On Thu, Jan 22, 2015 at 5:16 PM, ILM <[email protected] <javascript:>>
> wrote:
> >
> > 1/ Not having to have the Trigger class on the server classpath
>
> That doesn't make any sense - the function you call and the object it
> returns still needs to be on the server classpath.
>
Yes but it's still very useful since there's the whole JRE and H2 API, i.e.
you're not limited to the simple example I've provided where the custom
trigger class is on the server. You can declare a new anonymous trigger
class using only H2 and Java APIs, that way it works on any H2 server,
regardless of its class path.
> 2/ Allowing to pass parameters, e.g. you create once a trigger class to
> > update a last modified field and each table can have a different name
> for
> > this field
> > AS $$ org.h2.api.Trigger create(){ return new
> > LastModifiedTrigger("MODIFICATION_DATE"); } $$
> > for one table and
> > AS $$ org.h2.api.Trigger create(){ return new
> > LastModifiedTrigger("LAST_MOD_TIME"); } $$
> > for another
> >
>
> OK, I can see the benefit of this.
>
> Perhaps we make it even more convenient and make the construction look
> like:
>
> AS $$ myclass.CreateLastModifiedTrigger("MODIFICATION_DATE"); $$
>
> where H2 will assume that the code is a call to a method that returns
> an org.h2.api.Trigger object.
>
Why not, though I would prefix with the 'return' keyword, I think this
would be more legible and be easier for H2 to tell when we're passing a
full method and when we're only passing a statement.
Static method :
AS $$ return myclass.CreateLastModifiedTrigger("MODIFICATION_DATE"); $$
Constructor :
AS $$ return new LastModifiedTrigger("MODIFICATION_DATE"); $$
Complex code (e.g. as I've said above calling only H2 and JRE : works on
any H2 server) :
AS $$ org.h2.api.Trigger create(){
// as much statements as needed
String fieldName = "MODIFICATION_DATE";
Object someVar = ...
return new org.h2.api.Trigger {
init(){}
fire(){}
close(){}
remove(){}
};
} $$
Cheers,
Sylvain CUAZ
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