Re: get_object_or_404 on composite key and Value Error:Invalid Literal for int with base 10

On Dec 2, 12:10 am, bruno desthuilliers
<bruno.desthuilli...@gmail.com> wrote:
> On 1 déc, 19:20, Pranav <pranav...@gmail.com> wrote:
>
> > Hi all,
>
> > I'm new to django and python and i'm working on a project that works
> > with a legacy database.
> > I've a particular problem with a "composite key" and "get" or
> > "get_object_or_404".
>
> > i generated the below model form the legacy database using inspectdb
>
> > model:
> > ------------------
> > class Member:
>
> This should inherit from models.Model
>
> >            member_id = field.CharField(max_length=20)
> >            organization_id = field.Foreignkey(Organization)
> >            member_type = field.CharField(max_length=10)
> >            class Meta:
> >                     db_table = u'member'
> >                     unique_together =
> > (('member_id','organization_id'),)
> > # unique_together is a constraint i added in order to form the
> > composite primary key
>
> It's a composite key, but it's not a primary key - or at least it's
> not recognized as such by Django (hint: Django doesn't handle
> composite primary keys so far)
>
> > class Organization:
>
> idem
>
>
>
> > I have a function in my view which receives a "MemOrgId" which is
> > nothing but the composite key of both member_id and organization_id.
> > for example the value i get is MemOrgId='AA1001', now the problem is
> > when i try to use get or a get_object_or_404 i get a Value
> > Error:Invalid Literal for int with base 10.
>
> > obj = get_object_or_404(Member,pk = MemOrgId)
>
> Since you didn't explicitly declared a primary key for your Member
> model, Django automagically adds one, named "id" and defined as an
> autoincrement integer, so the 'pk' shortcut resolves to this int
> field.
>
> > According to my understanding of the trace back its not able to
> > convert the key "CP1001" to int coz it contains char data along with
> > int. I cannot modify the database
>
> Should not be a major problem.
>
> > and i cannot change the way MemOrgId
> > comes to the view function.
>
> Why ?
>
> > Is there a way around this problem????
>
> Yes: split the compound key and do an explicit lookup:
>
> def yourview(request, MemOrgId):
>     oid, mid = MemOrgId[0:2], MemOrgId[2:]
>     obj = get_object_or_404(
>        organization_id=oid,
>        member_id=mid
>        )
>
> IRL you probably want a bit more validation on what the MemOrgId arg
> looks like - but this can be done with the correct regexp in your
> urls.py

Thanks your solution worked, but now i have a bigger problem i cant
seem to save my form.
Django adds a automatic "id" to the table which i don't have in my
database so my database is throwing an error. Also none of the fields
in my table are unique so cannot set manual primary_key=True, I cannot
change the database as I said earlier. Is there a way to ignore this
auto generated id or a way to use the create a table without any
primary keys.

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