Re: Adding Unqiueness Constraint To List

> I did a quick test and no validation is not cascading
>
> def snippet =  new Snippet(
>    title:'Success Test',
>    category:'dummy',
>    code:"Simple Test",
>    tags:[new Tag(name:"test01")]
> )
>
> new Tag(name:"test04").save()
> assert snippet.validate() == true
>
> snippet.addToTags(new Tag(name:"test04"))
> assert snippet.validate() == true
>
> The last assert will pass even though it breaks the Tag.name unique constraint but when I attempt to do a save Hibernate throws a org.hibernate.exception.ConstraintViolationException.  Is this a bug or expected behaviour?  I would have thought at the very least this could be more graceful?
>
> James Hughes | Senior Software Engineer | Kainos | M: +353 (0)877 931 634 | j.hughes@...
>
> P Please consider the environment and do not print this mail unless necessary
>
> ________________________________
>
> From: elvanor@... on behalf of Jean-Noël Rivasseau
> Sent: Thu 15/05/2008 10:33
> To: user@...
> Subject: Re: [grails-user] Adding Unqiueness Constraint To List
>
>
>
> On Thu, May 15, 2008 at 11:15 AM, James Hughes <J.Hughes@...> wrote:
>> "as the uniqueness constraint you impose means that there cannot be two tags
>> with same name either - whereas you probably want to allow tags with
>> identical names if they belong to different snippets."
>>
>> No actually.  If a Tag for say "Java" exists I only want ONE instance of this and for it to be shared between multiple Snippets.  I can do this - I have proven it with some extra code in a controler class.  However I was just trying to tighten up my domain class constraints and came across this issue.
>
> Ha, I see. Then you are probably fine - you just have to learn if the
> validation code cascades (and as I said I would like to know the
> answer too).
>
>>
>> James Hughes | Senior Software Engineer | Kainos | M: +353 (0)877 931 634 | j.hughes@...
>>
>> P Please consider the environment and do not print this mail unless necessary
>>
>> ________________________________
>>
>> From: Jean-Noël Rivasseau [mailto:elvanor@...]
>> Sent: Thu 15/05/2008 10:12
>> To: user@...
>> Subject: Re: [grails-user] Adding Unqiueness Constraint To List
>>
>>
>>
>> Hi,
>>
>> I am also wondering myself if the validation code cascades, I am not
>> sure of this. Anyway you are probably doing things wrong - as the
>> uniqueness constraint you impose means that there cannot be two tags
>> with same name either - whereas you probably want to allow tags with
>> identical names if they belong to different snippets.
>>
>> I think you would need to write custom validation code to check if two
>> tags within a snippet have the same name. There's probably no built in
>> stuff to check that.
>>
>> On Thu, May 15, 2008 at 11:05 AM, James Hughes <J.Hughes@...> wrote:
>>> Actually apologies it seems I was doing something wrong.
>>>
>>> With the code below you can add the same Tag twice...
>>>
>>>        def snippet =  new Snippet(
>>>            title:'Success Test',
>>>            category:'dummy',
>>>            code:"Simple Test",
>>>            tags:[new Tag(name:"test01")]
>>>        )
>>>
>>>        assert snippet.validate() == true
>>>        snippet.addToTags(new Tag(name:"test02"))
>>>        assert snippet.validate() == true
>>>        snippet.addToTags(new Tag(name:"test04"))
>>>        assert snippet.validate() == true
>>>        snippet.addToTags(new Tag(name:"test04"))
>>>        assert snippet.validate() == true
>>>        snippet.addToTags(new Tag(name:"test04"))
>>>        assert snippet.validate() == true
>>>        snippet.addToTags(new Tag(name:"test04"))
>>>        assert snippet.validate() == true
>>>        snippet.addToTags(new Tag(name:"test04"))
>>>        assert snippet.validate() == true
>>>
>>> However if i create the Tag object first only a single unqiue entry is added for Tag(name:"test04").  Now I realise the code above creates 5 DIFFERENT Tag objects with the name of test04 but I was wondering why the unique constraint in Tag doesn't fail during validation?  I assume this is expected behaviour but I would like to know why?  Does the code not cascade constraints?
>>>
>>> Thanks
>>>
>>> James Hughes | Senior Software Engineer | Kainos | M: +353 (0)877 931 634 | j.hughes@...
>>>
>>> P Please consider the environment and do not print this mail unless necessary
>>>
>>> ________________________________
>>>
>>> From: James Hughes [mailto:J.Hughes@...]
>>> Sent: Thu 15/05/2008 09:38
>>> To: user@...
>>> Subject: [grails-user] Adding Unqiueness Constraint To List
>>>
>>>
>>>
>>> Hello,
>>>
>>> I am going to try and explain this as best I can.  I have 2 domain classes Snippet and Tag - they are reated by a Many-to-Many relationship -- they look like this
>>>
>>> class Snippet {
>>>    static hasMany = [tags:Tag]
>>>
>>>    String title
>>>    String description
>>>    String category
>>>    String code
>>>
>>>    static constraints = {
>>>        title(blank:false, nullable:false, maxSize:30)
>>>        description(blank:true, nullable:true, maxSize:300)
>>>        category(blank:false, nullable:false)
>>>        code(blank:false, nullable:false)
>>>        tags(size:1..10)
>>>    }
>>> }
>>>
>>> And tag
>>>
>>> class Tag {
>>>
>>>    static belongsTo = Snippet
>>>    static hasMany = [snippets:Snippet]
>>>
>>>    String name
>>>
>>>    static constraints = {
>>>        name(unique:true, blank:false, nullable:false)
>>>    }
>>>
>>>    boolean equals (Object other) {
>>>        name.equals(other.name)
>>>    }
>>> }
>>>
>>> What I am trying to do is add a constraint to the Snippet domain class so that you can't add the same Tag object twice.  I am pretty unsure of how to do this.  Can anyone offer assistance?
>>>
>>> Thanks
>>>
>>> James Hughes | Senior Software Engineer
>>>
>>> P Please consider the environment and do not print this mail unless necessary
>>>
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