To do an OR filter in a Python Django query, we can use Q and the | operator.
For instance, we write
from django.db.models import Q
Item.objects.filter(Q(creator=owner) | Q(moderated=False))
to call filter to search for Item items where creator is owner or moderated is False.
We call Q with the conditions we want and combine them with | to do the OR query.
To pass custom form parameters to Formset with Python Django, we call formset_factory and functools.partial.
For instance, we write
from functools import partial, wraps
from django.forms.formsets import formset_factory
ServiceFormSet = formset_factory(wraps(ServiceForm)(partial(ServiceForm, affiliate=request.affiliate)), extra=3)
to wrap the ServiceForm with wraps.
And then we call partial with Service and the argument we want to pass into ServiceForm.
And then we call (wraps(ServiceForm with the result returned by partial.
And then we call formset_factory on the result returned by wraps.
To programmatically saving image to Python Django ImageField, we can call save with the path we want to save the file to.
For instance, we write
from django.core.files import File
import urllib
result = urllib.urlretrieve(image_url)
self.photo.save(
os.path.basename(self.url),
File(open(result[0], 'rb'))
)
self.save()
in a model class method.
We call save on the photo ImageField with the path to save to as the argument.
And we save the file that we opened from urllib.urlretrieve method by creating a File object from it.
We create the file by call open with the result[0] file with read permission.
Finally, we call self.save to save the model data.
To dynamically add field to a form with Python Django, we can add the form with a for loop.
For instance, we write
class MyForm(forms.Form):
original_field = forms.CharField()
extra_field_count = forms.CharField(widget=forms.HiddenInput())
def __init__(self, *args, **kwargs):
extra_fields = kwargs.pop('extra', 0)
super(MyForm, self).__init__(*args, **kwargs)
self.fields['extra_field_count'].initial = extra_fields
for index in range(int(extra_fields)):
self.fields['extra_field_{index}'.format(index=index)] = \
forms.CharField()
to create the MyForm form that has a for loop in the __init__ method that creates CharFields and add them into the self.fields dictionary dynamically.
Then in our view, we can use the form with
def myview(request):
if request.method == 'POST':
form = MyForm(request.POST, extra=request.POST.get('extra_field_count'))
if form.is_valid():
print "valid!"
else:
form = MyForm()
return render(request, "template", { 'form': form })
We set the extra argument to a list we get from request.POST.get.
Then we render the template for the view with
<form>
<div id="forms">
{{ form.as_p }}
</div>
<button id="add-another">add another</button>
<input type="submit" />
</form>
To create a dynamic choice field with Python Django, we can set the fields to a queryset value.
For instance, we write
class WaypointForm(forms.Form):
def __init__(self, user, *args, **kwargs):
super(waypointForm, self).__init__(*args, **kwargs)
self.fields['waypoints'] = forms.ChoiceField(
choices=[(o.id, str(o)) for o in Waypoint.objects.filter(user=user)]
)
to create the WaypointForm form.
In the __init__ method, we set self.fields['waypoints'] to a ChoiceField.
And we populate the choices by setting the choices argument to a list of values that we get from the Waypoint.objects.filter(user=user) queryset.