Django: Multiple date fields in forms that allow blank entry issue - django

Question

I have a model in Django that allows blanks for two date fields:
class ReleaseStream(models.Model):
name = models.CharField(max_length=200,db_column='name')
version = models.CharField(max_length=20,blank=True,db_column='version')
target_date = models.DateTimeField(null=True,blank=True,db_column='target_date')
actual_date = models.DateTimeField(null=True,blank=True,db_column='actual_date')
description = models.TextField(db_column='description')
...and a form definition:
class ReleaseStreamForm(ModelForm):
class Meta:
model = ReleaseStream
When the form comes up, I can fill in a value for the "target_date", and not for the "actual_date" fields, and when the form.save() fires it appears to write the value supplied for "target_date" into both fields. I have looked at the post data going into the code that does the form.save() and it definitely has a value for "target_date" and a '' for "actual_date", so I don't think that there is something weird with the form itself, variable names in the POST, etc.
Now, if I supply a non-blank value for "actual_date", the form.save() does the right thing - both the "target_date" and "actual_date" have the correct values written in. Am I doing something wrong, or is this potentially a bug in django?
Here is the template (sorry for the blank comment below:)
{% extends "base.html" %}
{% block title %}{{ form_title }}{% endblock %}
{% block subtitle %}{% endblock %}
{% block content %}
<form action={{ action_url }} method="post">
<table>
{{ form.as_table }}
</table>
<input type="submit" value="Submit" />
</form>
{% endblock %}
And the code that handles the form:
def edit_release_stream(request,req_release_stream_id=None):
form_title = 'Edit release stream'
if request.method == 'POST':
if req_release_stream_id!=None:
release_stream_entry=ReleaseStream.objects.get(pk=req_release_stream_id)
form = ReleaseStreamForm(request.POST,instance=release_stream_entry)
else:
form = ReleaseStreamForm(request.POST)
if form.is_valid():
form.save()
return HttpResponseRedirect('/releases/')
elif req_release_stream_id!=None:
release_stream_entry=ReleaseStream.objects.get(pk=req_release_stream_id)
form = ReleaseStreamForm(instance=release_stream_entry)
else:
form_title = 'Add new release stream'
form = ReleaseStreamForm()
return render_to_response('dashboard/tableform.html', {
'action_url': request.get_full_path(),
'form_title': form_title,
'form': form,
})
... And the post data coming in:
<QueryDict: {u'name': [u'NewRelease'], u'target_date': [u'2011-06-15 00:00'], u'version': [u'4.5.1'], u'actual_date': [u''], u'description': [u'']}>
You can see that it has a valid POST var of "actual_date", with an empty string. This post yields a form.save() that stores the string provided above for "target_date" for both "target_date" and "actual_date".
If I then run a post with differing values for the two dates - here is the post:
<QueryDict: {u'name': [u'NewRelease'], u'target_date': [u'2011-06-15 00:00'], u'version': [u'4.5.1'], u'actual_date': [u'2011-07-15 00:00'], u'description': [u'']}>
In this case, with two distinct, non-empty strings, it writes the correct value shown in the POST above into each of the fields in the db.

Answer 1

I don't believe it to be a bug in Django, or somebody would have seen this problem a long time ago. Can you show us the template that renders the form? Also, if you can show the contents of the request.POST, that'd also be useful.
I'm guessing that your template code is incorrect somehow. The only other problem I can think of would be custom validation in your form (if there is any). Is that the whole ModelForm definition that you've supplied?