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Posted to users@isis.apache.org by Chuangyu <zh...@gmail.com> on 2015/07/13 03:20:02 UTC
How to avoid a method to be called multi times
Hi,
I create a defaultXXX method,in this method it fetchs a sequence number
like below
public Integer default0NewMaintainRequest(){
SequenceGenerator seq=seqGens.findGenerator();
Integer n=seq.getSequnceNumber();
n++;
seq.setSequenceNumber(n);
return n;
}
But it was called 2 times when invoke newMaintainRequest(Integer
code.....), and sequence number was plus 2 every time.
How can I avoid this behavior ?
Re: How to avoid a method to be called multi times
Posted by Chuangyu <zh...@gmail.com>.
Dan,
Thank you for your answer.
Actually my solution same as yours at last.
I modify defaultxxx function do not increase sequenceNumber to avoid
side-effects.
Database store next new sequence;
And show sequenceNumber default value to user.
2015-07-29 13:58 GMT+08:00 Dan Haywood <da...@haywood-associates.co.uk>:
> Apologies for not replying sooner on this one.
>
> I was going to reply that you shouldn't make any assumptions about how many
> times the supporting methods are called, and in general that's true... they
> should have no side-effects. After all, the user could hit cancel, in
> which case (in your original implementation) the sequence number would
> still have been incremented.
>
> In your particular use case, if the idea is that the system will
> automatically generate a value for the sequence number but the user can
> override, I would simply provide no default; then the logic to calculate
> the next value should be in the action itself, eg:
>
> public MaintainRequest newMaintainRequest(String sequenceNumber, ...) {
> if(sequenceNumber == null) {
> SequenceGenerator seq = seqGens.findGenerator();
> Integer n=seq.getSequnceNumber();
> n++;
> seq.setSequenceNumber(n);
> sequenceNumber = ""+ seqGens.getSequenceNumber();
> }
> ...
> }
>
> That said , I had a quick look at the Wicket UI code, and it turns out to
> be easy enough to change things to prevent the defaultXxx(...) being called
> multiple times. So I've raised and committed a fix for ISIS-1179.
>
> Thanks
> Dan
>
>
>
>
> On 13 July 2015 at 02:20, Chuangyu <zh...@gmail.com> wrote:
>
> > Hi,
> > I create a defaultXXX method,in this method it fetchs a sequence number
> > like below
> >
> > public Integer default0NewMaintainRequest(){
> > SequenceGenerator seq=seqGens.findGenerator();
> > Integer n=seq.getSequnceNumber();
> > n++;
> > seq.setSequenceNumber(n);
> > return n;
> > }
> >
> > But it was called 2 times when invoke newMaintainRequest(Integer
> > code.....), and sequence number was plus 2 every time.
> >
> > How can I avoid this behavior ?
> >
>
Re: How to avoid a method to be called multi times
Posted by Dan Haywood <da...@haywood-associates.co.uk>.
Apologies for not replying sooner on this one.
I was going to reply that you shouldn't make any assumptions about how many
times the supporting methods are called, and in general that's true... they
should have no side-effects. After all, the user could hit cancel, in
which case (in your original implementation) the sequence number would
still have been incremented.
In your particular use case, if the idea is that the system will
automatically generate a value for the sequence number but the user can
override, I would simply provide no default; then the logic to calculate
the next value should be in the action itself, eg:
public MaintainRequest newMaintainRequest(String sequenceNumber, ...) {
if(sequenceNumber == null) {
SequenceGenerator seq = seqGens.findGenerator();
Integer n=seq.getSequnceNumber();
n++;
seq.setSequenceNumber(n);
sequenceNumber = ""+ seqGens.getSequenceNumber();
}
...
}
That said , I had a quick look at the Wicket UI code, and it turns out to
be easy enough to change things to prevent the defaultXxx(...) being called
multiple times. So I've raised and committed a fix for ISIS-1179.
Thanks
Dan
On 13 July 2015 at 02:20, Chuangyu <zh...@gmail.com> wrote:
> Hi,
> I create a defaultXXX method,in this method it fetchs a sequence number
> like below
>
> public Integer default0NewMaintainRequest(){
> SequenceGenerator seq=seqGens.findGenerator();
> Integer n=seq.getSequnceNumber();
> n++;
> seq.setSequenceNumber(n);
> return n;
> }
>
> But it was called 2 times when invoke newMaintainRequest(Integer
> code.....), and sequence number was plus 2 every time.
>
> How can I avoid this behavior ?
>