On 23/10/2013 11:51am, Pepsodent Cola wrote:
I'm a beginner so I can only answer your first question. The below link
has helped me with 1:M and N:M relationship experiments.
Can someone point me to where this is explained in the docs (1.6)?
https://docs.djangoproject.com/en/1.6/topics/db/examples/
https://docs.djangoproject.com/en/1.6/ref/models/fields/#manytomanyfield
Also, a couple of paragraphs below that ...
https://docs.djangoproject.com/en/1.6/ref/models/fields/#django.db.models.ManyToManyField.through
... where it explains that you can have your own table for the m2m
relationship if you want to store data about the relationship itself.
For this to make sense you need to declare a model class for that table
with fields for the extra data. Note that this isn't necessary for
ordinary m2m relationships because Django does it implicitly.
Anyway, if you make an extra table, it needs a FK to each of the other
tables. Maybe like ...
class AuthorPaper(models.Model):
author = models.ForeignKey('Author')
paper = models.ForeignKey('Paper')
gossip = models.TextField()
Now this being a model in your own code means you can deal with it in
more or less the same way as all the other models in your views etc.
I haven't read the code below in any detail so this is probably off the
mark but there is a get_or_create method which might be useful.
https://docs.djangoproject.com/en/1.5/ref/models/querysets/#django.db.models.query.QuerySet.get_or_create
hth
Mike
On Tuesday, October 22, 2013 11:59:14 PM UTC+2, Timothy W. Cook wrote:
Can someone point me to where this is explained in the docs (1.6)?
I have a ManyToMany relationship in my models between Author and Paper.
I am processing an XML file to create records for Papers.
I want to check if an Author exists and if not create the record.
This was quite easy for Foreign Key relationships. But I can't get
my head around how to do this for ManyToMany. All of my Authors are
created correctly. But none are automatically selected for the Papers.
Some code:
class AuthorManager(models.Manager):
def create_author(self, name, email, affl):
a = self.create(name=name, email=email, affiliation=affl)
a.save()
return a
class Author(models.Model):
name = models.CharField("Name", max_length=255, db_index=True,
null=True, blank=True, help_text="")
email = models.EmailField("Email", max_length=255, null=True,
blank=True, help_text="")
affiliation = models.CharField("Affiliation", max_length=255,
null=True, blank=True, help_text="")
objects = AuthorManager()
def __str__(self):
return self.name <http://self.name>
def import_pubmed_xml(obj, f):
...
p =
Paper.objects.create_paper(ptitle,rid,jid,jyear,jvol,jissue,lang)
#authors
affl = article.xpath("./Affiliation/text()")
if affl: affl = affl[0]
else: affl = 'unknown'
affl = affl.strip()
authorlist = article.xpath("./AuthorList")
for authorentry in authorlist:
for author in authorentry:
lname = author.xpath("./LastName/text()")
if lname:
lname = lname[0]
else:
lname = 'unknown'
fname = author.xpath("./ForeName/text()")
if fname:
fname = fname[0]
else:
fname = 'unknown'
initials = author.xpath("./Initials/text()")
if initials:
initials = initials[0]
else:
initials = ''
a_name = (lname +', '+fname + ' ' +initials).strip()
print(a_name)
email = ''
#need to lookup Author by name then check
affiliation. If not found then create it.
try:
a = Author.objects.get(name=a_name)
p.authors.id <http://p.authors.id> = a.id <http://a.id>
p.save()
except ObjectDoesNotExist:
a = Author.objects.create_author(a_name, email,
affl)
p.authors.id <http://p.authors.id> = a.id <http://a.id>
p.save()
===================================================
Thanks in Advance,
Tim
--
MLHIM VIP Signup: http://goo.gl/22B0U
============================================
Timothy Cook, MSc +55 21 94711995
MLHIM http://www.mlhim.org
Like Us on FB: https://www.facebook.com/mlhim2
<https://www.facebook.com/mlhim2>
Circle us on G+: http://goo.gl/44EV5
Google Scholar: http://goo.gl/MMZ1o
LinkedIn Profile:http://www.linkedin.com/in/timothywaynecook
<http://www.linkedin.com/in/timothywaynecook>
--
You received this message because you are subscribed to the Google
Groups "Django users" group.
To unsubscribe from this group and stop receiving emails from it, send
an email to django-users+unsubscr...@googlegroups.com.
To post to this group, send email to django-users@googlegroups.com.
Visit this group at http://groups.google.com/group/django-users.
To view this discussion on the web visit
https://groups.google.com/d/msgid/django-users/ff993a02-baad-4a7d-ad39-529ddafd8861%40googlegroups.com.
For more options, visit https://groups.google.com/groups/opt_out.
--
You received this message because you are subscribed to the Google Groups "Django
users" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to django-users+unsubscr...@googlegroups.com.
To post to this group, send email to django-users@googlegroups.com.
Visit this group at http://groups.google.com/group/django-users.
To view this discussion on the web visit
https://groups.google.com/d/msgid/django-users/52676DAC.1030408%40dewhirst.com.au.
For more options, visit https://groups.google.com/groups/opt_out.
