My admin.py seems to work very well thank you, but my user has the option of clicking "Save" even when nothing has changed. This sets the object's modified_date field which annoys me.
Is there a way to force a cancel when using "Save" in these circumstances to close a change form in the admin? Is it desirable to do so?
You could probably write a custom admin form and subclass it for every admin-editable entity where, in the save() it looks at all fields which aren't the last_modified_date (I'm assuming you've got this consistently named across your models) and if there are no changes, doesn't call super(YourAdminFormClassNamehere, self).save(*args, **kwargs) but if there are changes to any of those fields, it does.
(It's a weekend, else I'd probably add some example code. This should get you on a useful track, though.)
Related
In my models, I have an Event class, a Volunteer class, and a Session class. The Session class has a foreign key field for an Event and a Volunteer, and is a unique coupling of both, as well as a date and time. Taken together, Volunteer and Event I think technically have a ManyToMany relationship.
Using the pre-packaged Django admin, I edit Volunteers and Events with their own admin.ModelAdmin classes respectively. Sessions are edited inline in the Events ModelAdmin.
When I add a new Session to an event in the admin interface, with a Volunteer, I need the Volunteer's hours field to be automatically updated, to reflect however many hours the newly added session lasted (plus all past sessions). Currently, I just have a calculate_hours function in the Volunteer model, which iterates over all sessions each time it is called and finds the sum of the hours. I tried to call it with a custom save function in Session, but it appears never to be called after the Event save function. I would try it in Event, but I have no way to isolate which Volunteers need their hours recalculated. The hours field IS updated if I manually go over to the Volunteer admin page, edit, and then save the Volunteer, but this is pretty unacceptable.
I see that there are many questions on SO about Django problems when saving inline objects on the admin site, particularly with ManyToMany fields. I'm not sure, after reading many of these questions, if what they say applies in my case--maybe I need to receive a signal somewhere, or include a custom save in a special place, or call save_model in my admin.ModelAdmin class... I just don't know. What is the best way to go about this?
Code can be found here: Models.py, Admin.py
First of all, the relationship you're describing is what called a ManyToMany "through" (you can read about it in the documentation here).
Secondly, I don't understand why you need the 'hours' to be a field at all. Isn't a function enough for this? why save it in the database in the first place? you can just call it every time you need it.
Finally, it seems to me you're doing a lot of extra work that I don't understand - why do you need the volunteer time boolean field? If you link a volunteer with an event isn't that enough to know that he was there? And what's the purpose of "counts_towards_volunteer_time"? I'm probably missing some of the logic here, but a lot of that seems wasteful.
Following a related (as yet unanswered) question, I did some investigation and found that the current implementation of Django Haystack's RealTimeSearchIndex makes no attempt to also update on related field (Many to Many) changes. I thought this would be an easy fix - after all, I could just extend RealTimeSearchIndex like this:
class RealTimeM2MSearchIndex(RealTimeSearchIndex):
def _setup_save(self, model):
signals.m2m_changed.connect(self.update_object, sender=model)
signals.post_save.connect(self.update_object, sender=model)
But then I realized (or at least assumed, since it's not working) that this only works if the M2M field is defined on the model itself, and not if it's the "reverse" side of the M2M relationship. Trying to fix that, I then did something like the following:
signals.m2m_changed.connect(self.update_object, sender=model.related_field.through)
Where related_field is the name of the specific Model on other side of the ManyToMany definition. Strangely enough, upon running, Django then complains that the Model has no such field, related_field.
And sure enough, if I inspect the object, Django has not yet extended the model to have the related_field field. If I inspect the same object when displaying a view, however, it does have that related_field.
Summary
So the problem seems to be that Django's automatic behavior to add an attribute to the reverse side of an M2M relationship has yet to happen when Haystack runs its code. How can I overcome this obstacle, and allow Haystack's RealTimeSearchIndex to also update on related field changes?
I think the simplest solution is to just use the built in RealTimeSearchIndex, and add a signal listener in your models.py to reindex the model on m2m_changed, or whenever. See my answer to the other question - you could easily modify it to index on m2m_changed instead of post_save.
Just tried implementing this myself, and your problem is the value of the sender argument in this line:
signals.m2m_changed.connect(self.update_object, sender=model)
I read the documentation for the m2m_changed signal and the sender will be something like MyModel.my_field.through so you need to use that. This means you can't have a generic class as you are trying to do, but will need to define the _setup_save method in each case, with the m2m_changed signal connected for each ManyToMany field that model has.
For example, if your model had two ManyToManyFields called region and sector, you could do:
# we implement these to force the update when the ManyToMany fields change
def _setup_save(self, model):
signals.m2m_changed.connect(self.update_object,
sender=MyModel.sector.through)
signals.m2m_changed.connect(self.update_object,
sender=MyModel.region.through)
signals.post_save.connect(self.update_object, sender=model)
You should also really define the _teardown_save() method:
def _teardown_save(self, model):
signals.m2m_changed.disconnect(self.update_object,
sender=MyModel.sector.through)
signals.m2m_changed.disconnect(self.update_object,
sender=MyModel.region.through)
signals.post_save.disconnect(self.update_object, sender=model)
(This is based on code I have tested, it appears to work - certainly no errors about fields not existing).
Update: Just read your question more closely. Is it possible that your model has the ManyToManyField added dynamically? Is the call to register() after you have defined all your classes?
So let's say at the last minute (in the view) I decide I want to specify a default for a field and make it hidden, like so:
form.fields['coconut'] = forms.ModelChoiceField(
label="",
widget=forms.HiddenInput(),
queryset=swallow.coconuts.all(),
initial=some_particular_coconut,
)
My question is this: Do I really need to specify queryset here? I mean, I already know, from initial, exactly which coconut I'm talking about. Why do I also need to specify that the universe of available coconuts is the set of coconuts which this particular swallow carried (by the husk)?
Is there a way I can refrain from specifying queryset? Simply omitting causes django to raise TypeError.
If indeed it is required, isn't this a bit damp?
I think is good that stackoverflow answers point to the 'right' way to do things, but increasingly the original question goes unanswered because the user was trying to do the wrong thing.
So to answer this question directly this is what you can do:
form.fields['coconut'] = forms.ModelChoiceField(label="", widget=forms.HiddenInput(attrs={'value':some_particular_coconut}), queryset=swallow.coconuts.all())
Notice the named argument passed to HiddenInput, its super hackish but its a direct answer to the original question.
The problem is that you're trying to set up a hidden ModelChoiceField. In order to have a Choice (dropdown, traditionally) it needs to know its Choices - this is why you give a queryset.
But you're not trying to give the user a choice, right? It's a hidden input, and you're setting it from the server (so it gets POSTed back, presumably).
My suggestion is to try to find a way around using the hidden input at all. I find them a bit hacky. But otherwise, why not just specify a text field with some_particular_coconut.id, and hide that? The model's only wrapping that id anyway.
The reason django requires a queryset is because when you render the field to the page, django only sends the id. when it comes back, it needs knowlege of the queryset in order to re-inflate that object.
if you already know the queryset at form creation time, why not simply specify form.fields['coconut'].initial = some_particular_coconut in your view and leave the rest of the definition in your forms.py?
If you find that you only really need to send the id anyway (you don't have to re-inflate to an object at your end), why not send it in a char field?
I have a view that handles a POST request and attempts to create a new object. However, I know that some of the POST'd data is invalid... But I want to fix it and go ahead and create the object.
The only way I can figure out to be able to 'fix' data in a ModelForm is to create a 'is_valid()' form. To do this, I can either create the form with the POST data, or I can create it with an already existing instance. Unfortunately, if I use the POST data, because some of it is invalid, the form won't validate and I am thus unable to get to the data in the form to fix it. If I create it with an already existing instance, this works, but when the form is displayed, any remaining errors are for whatever reason ignored (and thus don't show up on the web page.) I've tried a combination of creating the the Model form from the POST data and giving it an instance, but this doesn't seem to help. Additionally, I've tried modifying (a copy of) the POST data, fixing it, and then creating the ModelForm from the 'fixed' POST data. This sort of works, with the exception that I have some ImageFields in my form, and they seem to just be ignored.
Any help would be greatly appreciated. I have looked at every good page that I can find to no avail.
Perhaps there is a better way to do this? The problem I'm trying to solve is that I want to have a model that contains ImageFields. The first time I put up the form, the user needs to 'upload' images for each of the fields. However, if he doesn't update an image for one of the fields, I want the new form to come up with a Image upload button on the fields where images have not been uploaded, and just a text field with the image name for images that have been uploaded.
Edit 9/15/2010:
Ok, I think I can simplify all of the above question into this:
def testing( request ) :
test_form = UserProfileForm()
valid = test_form.is_valid()
return render( 'testing.tmpl', locals(), request )
When the above code is rendered, the 'valid' shows as False (as one might expect), but the 'test_form' renders without any errors. I've read through (if perhaps not understood?) the documentation on Models and ModelForms, and I see that most of the time a ModelForm (in my case: UserProfileForm) is created with a specified 'instance'. However, 1) I don't have an instance yet, 2) I would still expect the non-instance'd Form to display errors. I'm sure there is something I am missing. Please illuminate. :)
One more thing, which perhaps the answer to the above will answer anyway, but as far as I can tell, the is_valid() call is supposed to call the 'clean()' function I defined for the UserProfileForm. However, (not being a python guru) I placed 'raise ValidationError()' at the top of clean(), and when I run the code, no error is shown. Thoughts?
Update: I figured out the problem and the answer is below. Thanks!
You should have a look at how to clean form fields in django. You could either manipulate the data returned from the form there or make any kind of validation!
If your ImageFields are optional then you can still validate them (that they are otherwise correct).
Then it's a matter of adjusting your template to show either the uploaded file name or an file upload field depending on whether they've already uploaded one or not. Actually, it would probably be better to give them both fields in the first case. That's what the automatic admin does (the upload field is labeled "Change").
Well, after figuring out how to use the python debugger (pdb) and the fact that within emacs it kind of 'just works' (wow!?) I was able to find that my (empty) form was not bound. Googling bound forms pointed me to this page:
http://docs.djangoproject.com/en/dev/ref/forms/api/
RTFM'ing I find that I can pass an empty dictionary to my form and then everything starts to behave as I would expect. So, to summarize, there is a big difference between:
test_form = UserProfileForm()
and
test_form = UserProfileForm( {} )
The second version causes the rendering of the form to show all the errors (and to call 'clean()').
With risk of having this deleted by the moderator ;) Thank you to all those who commented and for your patience with a new django developer.
I'd like to create/update a "sub-object" within an admin edit dialog.
I have a "CmsObject" model, which contains several "CmsPageItem" objects (currently there will be just one fixed CmsPageItem, but that will change in the future). Rather then letting a StackedInline widget control the layout, I would like to display one additional textarea field somewhere in the change_form.html page.
What would the recommended approach to extend the ModelAdmin dialog be?
I expect I need to push a formfield somewhere, or introduce new values in the template context?
Have you looked at TabularInlines? There is an example here: http://docs.djangoproject.com/en/dev/intro/tutorial02/
I've eventually settled to implement the whole view myself. For most simple objects, implementing the inlines (either with a custom template, or without) is good enough. In this situation I require more control, so I've overwritten the entire add_view and change_view completely.
FeinCMS also does this for it's editor window.