Hi,
So a brief update. I changed the way I was building this model and
explicitly created a 'joining' table and added a through clause to the
ManyToManyField definition as well as allowing null values. This meant
I was able to populate the joining table using YAML after building the
test/instance tables using the natural keys for each of 'test' and
'instance'.
However when I view the table in the admin interface there is no
multiple selector for 'test' when I edit the instance in the admin
interface. I have added the joining table to the list of admin tables
(if this makes a difference).
Can anyone explain to me whether this is another error on my part, or
if it is expected that if you explicitly define a joining table then
Django suppresses the management of the relationship outside of the
joining table itself?
Obviously if it were possible to use the built in manytomany
management and be able to import the YAML defining this that I
included in the initial question that would be favourable.
For context this is a simplified example of a reasonably large
database that I am trying to port to a Django model so manually
building the contents of the joining table is not a reasonable
solution. I can generate the YAML, or similar, fairly trivially and so
it is best for me to build the fixtures to get the initial DB set up
and import them after the initial syndb.
Any guidance on this would be much appreciated - I am really enjoying
the elegance of Django but little issues caused by my (lack of)
understanding are definitely holding me up!
Regards
Stephen
On Mar 26, 12:01 pm, sk <6b656...@gmail.com> wrote:
> Hi,
>
> I have searched high and low to an answer to this, but have been
> unable too turn anything up. Apologies if I have overlooked an answer
> or explanation elsewhere.
>
> I have set up a very simple model as follows:
> ---------------------------------------------------------------------------
> from django.db import models
> class TestManager(models.Manager):
> def get_by_natural_key(self, name):
> return self.get(name=name,)
>
> class Test(models.Model):
> name = models.CharField(max_length = 100, unique = True)
> date = models.DateField()
>
> def __unicode__(self):
> return self.name
>
> def natural_key(self):
> return (self.name)
>
> class InstanceManager(models.Manager):
> def get_by_natural_key(self, name):
> return self.get(name=name,)
>
> class Instance(models.Model):
> name = models.CharField(max_length = 100, unique = True)
> test = models.ManyToManyField(Test)
> date = models.DateField()
>
> def __unicode__(self):
> return self.name
>
> def natural_key(self):
> return (self.name)
> ---------------------------------------------------------------
>
> looking at the admin interface I am able to add a couple of
> 'tests' (test 1 and test 2). I am then able to add an instance which
> is linked to both test 1 and test 2. If I dump the data to YAML format
> then I get the following (for the two tables in question):
>
> ---------------------------------------------------------------
> - fields: {date: 2012-03-26, name: test 1}
> model: TempDB.test
> pk: 1
> - fields: {date: 2012-03-26, name: test 2}
> model: TempDB.test
> pk: 2
> - fields:
> date: 2012-03-26
> name: Instance 1
> test: [test 1, test 2]
> model: TempDB.instance
> pk: 1
> ---------------------------------------------------------------
>
> This is roughly what I would expect to see, although the documentation
> does not explicitly state that a manytomany serialization will be a
> multi-element list, it seems to be a reasonable assumption.
>
> When I try to perform a loaddata with this output (and after manually
> deleting the tables from the admin interface, to be sure). I get the
> following error:
>
> Problem installing fixture '/home/XXXX/workspace/THMDB/THMDB/TempDB/
> fixtures/test.yaml': Traceback (most recent call last):
> File "/usr/local/lib/python2.7/dist-packages/Django-1.4-py2.7.egg/
> django/core/management/commands/loaddata.py", line 190, in handle
> for obj in objects:
> File "/usr/local/lib/python2.7/dist-packages/Django-1.4-py2.7.egg/
> django/core/serializers/pyyaml.py", line 62, in Deserializer
> raise DeserializationError(e)
> DeserializationError: [u"'test 1' value must be an integer."]
>
> What exactly have I done wrong? I suspect I have made an error in
> defining the managers. I have defined two as I planned to link too
> instances from another table. I left in the definition in case it is
> the cause of the error. However it still does the same thing if I
> comment it out.
>
> I am running Django 1.4 on python 2.7 under Ubuntu 11.10.
>
> Many thanks for your help.
>
> Stephen
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