TemplateSyntaxError: Caught an exception while rendering: coercing to Unicode: need string or buffer, long found

[SnappyDjangoUser]

Hi Folks,

I am receiving an obscure TemplateSyntaxError (Caught an exception
while rendering: coercing to Unicode: need string or buffer, long
found ) when rending a ModelForm that has a foreign key back to a
specific table. My template correctly renders forms for all models
except for this one case and I have not been able to figure out why.

AssetForm correctly renders fields on its own. The problem occurs
when rendering the RackForm which has a foreign key to the Asset
model.

Other models have foreign key relationships and those fields are
rendered correctly. The only clue I have is that the model giving me
trouble, Asset, has an unsigned IntegerField of length 12
(Asset_Number). See below for model information:


class Asset(models.Model):
idAsset = models.IntegerField(primary_key=True)
Asset_Number = models.PositiveIntegerField(max_length=12,
verbose_name='Asset Number')
class Meta:
db_table = 'Asset'
def __unicode__(self):
return self.Asset_Number

class Rack(models.Model):
idRack = models.IntegerField(primary_key=True)
SerialNumber = models.CharField(max_length=135)
RackLocation = models.CharField(blank=True, max_length=30)
Vendor_idVendor = models.ForeignKey(Vendor,
db_column='Vendor_idVendor')
Facility_idFacility = models.ForeignKey(Facility, null=True,
db_column='Facility_idFacility', blank=True)
Asset_idAsset = models.ForeignKey(Asset,
db_column='Asset_idAsset', max_length=12)
class Meta:
db_table = 'Rack'
def __unicode__(self):
return self.RackLocation


class AssetForm(ModelForm):
class Meta:
model = Asset
exclude = ['idAsset']

class RackForm(ModelForm):
class Meta:
model = Rack
exclude = ['idRack']


Template Snippet with the error:
18 <table>
19 {% for field in form %}
20 <tr>
21 <th>{{ field.label_tag }}{% if field.field.required %}*{% endif
%}</th>
22 <td>{{ field }}{% if field.help_text %}<br>{{ field.help_text }}</
br>{% endif %}</td>
23 {% if field.errors %}<td class="myerrors">{{ field.errors }}</
td>{% endif %}
24 </tr>
25 {% endfor %}
26 </table>

Django says that the error is occuring at line 19, but I have not been
able to figure out why. Any ideas? Like I said above, this template
works just fine for most cases. The only case that gives me problems
is when rendering the RackForm (which has a foreign key to Asset).

Thanks in advance for the help...

[Daniel Roseman]

The error is fairly descriptive: it's trying to convert something to
unicode, but is only receiving a Long integer value.

The problem lies in the __unicode__ method of the Asset field. This
method isn't returning a unicode value as it should, but the contents
of the Asset_Number field - which is a PostiveInteger. Django uses the
__unicode__ method to display the values in the drop-down field for
Asset_idAsset. (Weird field names, by the way: Django/Python
convention is to use lower_case_with_underscores for field names, and
CapsCase for class/model names.)

You should rewrite it along these lines:

def __unicode__(self):
return u'%s' % self.Asset_Number

--
DR