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Subject: Re: Validation and @PrePersist
From: "Musall, Maik" <maik@selbstdenker.ag>
In-Reply-To: <F2A26925D2944F64A058FB5B37F69B0F@IV5>
Date: Thu, 2 Mar 2017 09:49:10 +0100
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To: user@cayenne.apache.org
archived-at: Thu, 02 Mar 2017 08:49:22 -0000

Hi Jurgen,

> Am 02.03.2017 um 09:33 schrieb dollj@xsinet.co.za:
>=20
> I agree with your reasoning.  So then the original description of how =
lifecycle events should behave in 3.1 is conceptually better (i.e. that =
PrePersist & PreUpdate occur before validation), and the historical =
behaviour is then a bug ?

That would be my conclusion, too.

> It would be good for this to be changed, unless there's backward =
compatibility issues  :-)

Well, there's no better time to change this than at the beginning of M6, =
right? :-)

Maik


>=20
> -----Original Message----- From: Musall, Maik
> Sent: Thursday, March 2, 2017 9:53 AM
> To: user@cayenne.apache.org
> Subject: Re: Validation and @PrePersist
>=20
> Hi Jurgen,
>=20
> PostAdd is fine for seting a createDate, but what about an updateDate =
or something similar? If these assertions are all true:
>=20
> 1. validation is supposed to not change attributes
> 2. no more changes should be made after validation happened
> 3. PrePersist runs after validation
>=20
> then there is just no place left to set something like an updateDate. =
Also, PrePersist would be restricted to do read-only checks that you can =
also do during validation, which makes no sense to me conceptually.
>=20
> Maik
>=20
>=20
>=20
>> Am 02.03.2017 um 07:56 schrieb dollj@xsinet.co.za:
>>=20
>> Hi All
>>=20
>> We had a similar discussion Sept-Oct 2012 where it was noted that =
there was a discrepancy between the docs and the implementation. That =
was with 3.1B where the behaviour was the same as it is now, i.e. =
validation occurs before PrePersist (but as noted by Michael the 3.1 =
docs incorrectly state "after" ).
>>=20
>> So I assume that subsequently the docs were updated for cayenne 4 to =
correctly reflect the behaviour.
>>=20
>> Back then it was stated that PostAdd was the correct place to do this =
kind of thing, which I think is fine for fields that have standard =
default values.
>>=20
>> It can get a bit clumsy sometimes where you sometimes have to have =
both PostAdd and PrePersist doing the same thing. For example for a =
timestamp field where object entity creation (PostAdd) occurs much =
earlier than the commit (PrePersist), but you want the commit timestamp. =
This is where I would have preferred the behaviour that Hugi is looking =
for where PrePersist is called first, before validation.
>>=20
>> Cheers,
>> Jurgen
>>=20
>>=20
>> -----Original Message----- From: Michael Gentry
>> Sent: Wednesday, March 1, 2017 5:38 PM
>> To: Cayenne Users
>> Subject: Re: Validation and @PrePersist
>>=20
>> Hi Hugi,
>>=20
>> I was indeed looking at < 4.  No idea why the change was made.  =
Perhaps
>> someone else can answer that one...
>>=20
>> Thanks,
>>=20
>> mrg
>>=20
>>=20
>> On Wed, Mar 1, 2017 at 10:03 AM, Hugi Thordarson <hugi@godurkodi.is> =
wrote:
>>=20
>>> Hi Michael,
>>> the documentation was apparently changed for 4.0 in 2015 to reflect =
the
>>> current behaviour:
>>>=20
>>> =
https://github.com/apache/cayenne/commit/5bb12cd36f0d87e3b217cdc20c22a0
>>> f6dc9613f3#diff-5b9a57288e30ef9855d80a63a812ec4f
>>>=20
>>> Cheers,
>>> - hugi
>>>=20
>>>=20
>>> > On 1. mar. 2017, at 14:59, Michael Gentry <blacknext@gmail.com> =
wrote:
>>> >
>>> > Hi Hugi,
>>> >
>>> > If validateForInsert() is being called before PrePersist, we have =
a
>>> > disconnect between the documentation and the behavior you are =
seeing:
>>> >
>>> > "PrePersist: right before a new object is committed, inside
>>> > ObjectContext.commitChanges() and =
ObjectContext.commitChangesToParent()
>>> > (and prior to validateForInsert())."
>>> >
>>> > What version of Cayenne are you using?  I wonder if something has =
> > changed
>>> > or if the documentation is just wrong.
>>> >
>>> > Thanks,
>>> >
>>> > mrg
>>> >
>>> >
>>> >
>>> > On Wed, Mar 1, 2017 at 6:18 AM, Hugi Thordarson =
<hugi@godurkodi.is>
>>> wrote:
>>> >
>>> >> Hi all,
>>> >> I have some logic in a Listener that uses @PrePersist to populate =
the
>>> >> value of a required attribute before committing changes. Turns =
out >> this
>>> >> doesn=E2=80=99t work, since Cayenne invokes validateForInsert() =
before running
>>> >> @PrePersist.
>>> >>
>>> >> Any suggestions for where I can invoke logic populates required =
values
>>> >> before validation?
>>> >>
>>> >> Cheers,
>>> >> - hugi
>>>=20
>>=20
>=20