How do I access the fields of a link-table with Lift Mapper? - Lift

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Message from discussion How do I access the fields of a link-table with Lift Mapper?
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Date: Thu, 11 Oct 2012 16:48:34 -0400
Message-ID: <CAE-RkXjiLWVRn+SgFPZNQNZAiDQBpY67j6y4wL9Aqrr74Xi...@mail.gmail.com>
Subject: Re: [Lift] How do I access the fields of a link-table with Lift Mapper?
From: Diego Medina <di...@fmpwizard.com>
To: liftweb@googlegroups.com
Content-Type: text/plain; charset=ISO-8859-1

ok, so, from where do you want to access the fields in
AssignmentformLink? What is your starting point?

Thanks

  Diego

On Thu, Oct 11, 2012 at 4:27 PM, Jacobus <jacobusreyn...@gmail.com> wrote:
> Hi,
>
> Thanks for the advice and link. The mapping as I have described it does
> work, but I don't know how to get to the link-table's fields. It must be
> possible.... I hope :-p
>
> Kind regards,
> Jacobus
>
>
> On Thursday, 11 October 2012 21:00:34 UTC+2, fmpwizard wrote:
>>
>> Hi, You don;t have your ManyToMany relationship defined right (or
>> maybe I'm missing something)
>>
>> from here:
>>
>>
>> class Assignment extends LongKeyedMapper[Assignment] with IdPK with
>> ManyToMany {
>>   def getSingleton = Assignment
>>
>>   object id_parent extends MappedLong(this)
>>
>>   object label extends MappedString(this, 40)
>>
>>   object order extends MappedInt(this)
>>
>>   object guard extends MappedString(this, 200)
>>
>>   object forms extends MappedManyToMany(
>>     AssignmentformLink, AssignmentformLink.assignment,
>> AssignmentformLink.form, TForm
>>   )
>>
>> }
>>
>>
>>
>> these lines
>>
>>   object forms extends MappedManyToMany(
>>     AssignmentformLink, AssignmentformLink.assignment,
>> AssignmentformLink.form, TForm
>>   )
>>
>> one of the two tables there should the the class enclosing the object
>> forms, maybe, in SQL, how are your tables related, so I can better
>> help you, also, you may want to look at this wiki page (which I find
>> very useful), about mapper and manyTOMany:
>>
>>
>> https://www.assembla.com/spaces/liftweb/wiki/mapper#manytomany
>>
>>
>> Thanks
>>
>>   Diego
>>
>>
>> On Thu, Oct 11, 2012 at 2:33 PM, Jacobus <jacobus...@gmail.com> wrote:
>> > Hi there,
>> >
>> > I've asked this question on stack-overflow
>> > (http://stackoverflow.com/q/12843590/828757). I hope the lift forum will
>> > be
>> > able to give me some guidance:
>> >
>> > From the Lift-Web Mapper model below, how do I access the fields under
>> > AssignmentformLink?
>> >
>> >     object TForm extends TForm with LongKeyedMetaMapper[TForm]
>> >
>> >     class TForm extends LongKeyedMapper[TForm] with IdPK with ManyToMany
>> > {
>> >       def getSingleton = TForm
>> >
>> >       object label extends MappedString(this, 40)
>> >
>> >       object pattern extends MappedString(this, 200)
>> >
>> >       object assignments extends MappedManyToMany(
>> >           AssignmentformLink, AssignmentformLink.assignment,
>> > AssignmentformLink.form, TForm)
>> >
>> >     }
>> >
>> >     object AssignmentformLink extends AssignmentformLink with
>> > LongKeyedMetaMapper[AssignmentformLink] {
>> >       override def dbIndexes = Index(form, assignment) ::
>> > super.dbIndexes
>> >     }
>> >
>> >     class AssignmentformLink extends LongKeyedMapper[AssignmentformLink]
>> > with IdPK {
>> >       def getSingleton = AssignmentformLink
>> >
>> >       object form extends MappedLongForeignKey(this, TForm)
>> >
>> >       object assignment extends MappedLongForeignKey(this, Assignment)
>> >
>> >       object order extends MappedInt(this)
>> >
>> >       object readonly extends MappedBoolean(this)
>> >
>> >       object required extends MappedBoolean(this)
>> >
>> >       object visible extends MappedBoolean(this)
>> >
>> >     }
>> >
>> >     object Assignment extends Assignment with
>> > LongKeyedMetaMapper[Assignment]
>> >
>> >     class Assignment extends LongKeyedMapper[Assignment] with IdPK with
>> > ManyToMany {
>> >       def getSingleton = Assignment
>> >
>> >       object id_parent extends MappedLong(this)
>> >
>> >       object label extends MappedString(this, 40)
>> >
>> >       object order extends MappedInt(this)
>> >
>> >       object guard extends MappedString(this, 200)
>> >
>> >       object forms extends MappedManyToMany(
>> >           AssignmentformLink, AssignmentformLink.assignment,
>> > AssignmentformLink.form, TForm)
>> >
>> >     }
>> >
>> > To get an assignmet and the forms linked to it, you do this:
>> >
>> >     val assignments = Assignments.find(By(Assignment.id, 123))
>> >
>> >     assignments match {
>> >       case Full(as) => {
>> >         val forms = as.forms
>> >     .....
>> >
>> > But I have no idea how to navigate to the `order, readonly, required...`
>> > fields under `AssignmentformLink`.
>> >
>> > I realise I can search for the link manually, ie.
>> > `AssignmentformLink.find(By(form...),By(assignment...))`, but this will
>> > result in inefficient code and really misses the point of using objects.
>> >
>> > I need to be able to *navigate* from the form to the link table's
>> > fields.
>> >
>> > Kind regards,
>> > Jacobus
>> >
>> > --
>> > --
>> > Lift, the simply functional web framework: http://liftweb.net
>> > Code: http://github.com/lift
>> > Discussion: http://groups.google.com/group/liftweb
>> > Stuck? Help us help you:
>> > https://www.assembla.com/wiki/show/liftweb/Posting_example_code
>> >
>> >
>> >
>>
>>
>>
>> --
>> Diego Medina
>> Lift/Scala Developer
>> di...@fmpwizard.com
>> http://www.fmpwizard.com
>
> --
> --
> Lift, the simply functional web framework: http://liftweb.net
> Code: http://github.com/lift
> Discussion: http://groups.google.com/group/liftweb
> Stuck? Help us help you:
> https://www.assembla.com/wiki/show/liftweb/Posting_example_code
>
>
>



-- 
Diego Medina
Lift/Scala Developer
di...@fmpwizard.com
http://www.fmpwizard.com
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