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  • Django ORM and multiprocessing

    - by Ankur Gupta
    Hi, I am using Django ORM in my python script in a decoupled fashion i.e. it's not running in context of a normal Django Project. I am also using the multi processing module. And different process in turn are making queries. The process ran successfully for an hr and exited with this message "IOError: [Errno 32] Broken pipe" Upon futhur diagnosis and debugging this error pops up when I call save() on the model instance. I am wondering Is Django ORM Process save ? Why would this error arise else ? Cheers Ankur

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  • How do you handle the deletion of your model working with ViewModels and keeping them in sync ?

    - by Lisa
    Hello, these could be my entity relations: 1 Pupil has 1 Chair 1 Pupil has N Documents 1 Pupil has N Marks 1 Pupil has N IncidentReports etc... So with that sample I get 4 IEnumerable from my database put each into an ObservableCollection. Now I have 4 different Views each bound to one of those 4 collections. Lets assume I delete a single PupilViewModel in the AdministrationController which is the only View where I can delete a PupilViewModel. Now I have to inform 3 other Controller and their ObservableCollections about the one deleted PupilViewModel to keep the whole application synchronized... thats stupid somehow. Do you have any good advice on that scenario? AND it gets even worse. If I delete a schoolclass I have to sync the pupils everywhere AND the documents or incidentreports or marks... gush... o_O

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  • How to determine the maximum integer the model can handle?

    - by John Mee
    "What is the biggest integer the model field that this application instance can handle?" We have sys.maxint, but I'm looking for the database+model instance. We have the IntegerField, the SmallIntegerField, the PositiveSmallIntegerField, and a couple of others beside. They could all vary between each other and each database type. I found the "IntegerRangeField" custom field example here on stackoverflow. Might have to use that, and guess the lowest common denominator? Or rethink the design I suppose. Is there an easy way to work out the biggest integer an IntegerField, or its variants, can cope with?

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  • How to setup default attributes in a ruby model

    - by webdestroya
    I have a model User and when I create one, I want to pragmatically setup some API keys and what not, specifically: @user.apikey = Digest::MD5.hexdigest(BCrypt::Password.create("jibberish").to_s) I want to be able to run User.create!(:email=>"[email protected]") and have it create a user with a randomly generated API key, and secret. I currently am doing this in the controller, but when I tried to add a default user to the seeds.rb file, I am getting an SQL error (saying my apikey is null). I tried overriding the save definition, but that seemed to cause problems when I updated the model, because it would override the values. I tried overriding the initialize definition, but that is returning a nil:NilClass and breaking things. Is there a better way to do this?

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  • Django App for Image heavy Magazine Publishing?

    - by stapler
    I'm about to begin work on a Django project for an image heavy non-profit "community arts" magazine. The magazine is published monthly with about 6-8 articles that include with 4-10 images. I've been looking around for other projects that people have started specifically for publishing in Django... Are there any publishing specific Django apps you'd recommend? At the moment the only thing I can find is django-newsroom which looks interesting. Currently I'm just Image Kit / Photologue to attach galleries to an Article Model... but I'd love to figure out a way to more fully integrate images into the article content. Thanks in advance

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  • Best way to change Satchmo checkout page fields?

    - by konrad
    For a Satchmo project we have to change the fields a customer has to fill out during checkout. Specifically, we have to: Add a 'middle name' field Replace the bill and delivery addressee with separate first, middle and last name fields Replace the two address lines with street, number and number extension These fields are expected by an upstream web service, so we need to store this data separately. What's the best way to achieve this with minimal changes in the rest of Satchmo? We prefer a solution in which we do not have to change the Satchmo code itself, but if required we can fork it.

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  • How to make a model instance read-only after saving it once?

    - by Ryszard Szopa
    One of the functionalities in a Django project I am writing is sending a newsletter. I have a model, Newsletter and a function, send_newsletter, which I have registered to listen to Newsletter's post_save signal. When the newsletter object is saved via the admin interface, send_newsletter checks if created is True, and if yes it actually sends the mail. However, it doesn't make much sense to edit a newsletter that has already been sent, for the obvious reasons. Is there a way of making the Newsletter object read-only once it has been saved? Edit: I know I can override the save method of the object to raise an error or do nothin if the object existed. However, I don't see the point of doing that. As for the former, I don't know where to catch that error and how to communicate the user the fact that the object wasn't saved. As for the latter, giving the user false feedback (the admin interface saying that the save succeded) doesn't seem like a Good Thing. What I really want is allow the user to use the Admin interface to write the newsletter and send it, and then browse the newsletters that have already been sent. I would like the admin interface to show the data for sent newsletters in an non-editable input box, without the "Save" button. Alternatively I would like the "Save" button to be inactive.

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  • Invalidating Memcached Keys on save() in Django

    - by Zack
    I've got a view in Django that uses memcached to cache data for the more highly trafficked views that rely on a relatively static set of data. The key word is relatively: I need invalidate the memcached key for that particular URL's data when it's changed in the database. To be as clear as possible, here's the meat an' potatoes of the view (Person is a model, cache is django.core.cache.cache): def person_detail(request, slug): if request.is_ajax(): cache_key = "%s_ABOUT_%s" % settings.SITE_PREFIX, slug # Check the cache to see if we've already got this result made. json_dict = cache.get(cache_key) # Was it a cache hit? if json_dict is None: # That's a negative Ghost Rider person = get_object_or_404(Person, display = True, slug = slug) json_dict = { 'name' : person.name, 'bio' : person.bio_html, 'image' : person.image.extra_thumbnails['large'].absolute_url, } cache.set(cache_key) # json_dict will now exist, whether it's from the cache or not response = HttpResponse() response['Content-Type'] = 'text/javascript' response.write(simpljson.dumps(json_dict)) # Make sure it's all properly formatted for JS by using simplejson return response else: # This is where the fully templated response is generated What I want to do is get at that cache_key variable in it's "unformatted" form, but I'm not sure how to do this--if it can be done at all. Just in case there's already something to do this, here's what I want to do with it (this is from the Person model's hypothetical save method) def save(self): # If this is an update, the key will be cached, otherwise it won't, let's see if we can't find me try: old_self = Person.objects.get(pk=self.id) cache_key = # Voodoo magic to get that variable old_key = cache_key.format(settings.SITE_PREFIX, old_self.slug) # Generate the key currently cached cache.delete(old_key) # Hit it with both barrels of rock salt # Turns out this doesn't already exist, let's make that first request even faster by making this cache right now except DoesNotExist: # I haven't gotten to this yet. super(Person, self).save() I'm thinking about making a view class for this sorta stuff, and having functions in it like remove_cache or generate_cache since I do this sorta stuff a lot. Would that be a better idea? If so, how would I call the views in the URLconf if they're in a class?

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  • Manually listing objects in Django (problem with field ordering)

    - by Chris
    I'm having some trouble figuring out the best/Djangoic way to do this. I'm creating something like an interactive textbook. It has modules, which are more or less like chapters. Each module page needs to list the topics in that module, grouped into sections. My question is how I can ensure that they list in the correct order in the template? Specifically: 1) How to ensure the sections appear in the correct order? 2) How to ensure the topics appear in the correct order in the section? I imagine I could add a field to each model purely for the sake of ordering, but the problem with that is that a topic might appear in different modules, and in whatever section they are in there they would again have to be ordered somehow. I would probably give up and do it all manually were it not for the fact that I need to have the Topic as object in the template (or view) so I can mark it up according to how the user has labeled it. So I suppose my question is really to do with whether I should create the contents pages manually, or whether there is a way of ordering the query results in a way I haven't thought of. Thanks for your help!

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  • Where to delete model image?

    - by WesDec
    I have a Model with an image field and I want to be able to change the image using a ModelForm. When changing the image, the old image should be deleted and replaced by the new image. I have tried to do this in the clean method of the ModelForm like this: def clean(self): cleaned_data = super(ModelForm, self).clean() old_profile_image = self.instance.image if old_profile_image: old_profile_image.delete(save=False) return cleaned_data This works fine unless the file indicated by the user is not correct (for example if its not an image), which result in the image being deleted without any new images being saved. I would like to know where is the best place to delete the old image? By this I mean where can I be sure that the new image is correct before deleting the old one?

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  • Accessing updated M2M fields in overriden save() in django's admin

    - by Jonathan
    I'd like to use the user updated values of a ManyToManyField in a model's overriden save() method when I save an instance in admin. It turns out that by design, django does not update the M2M field before calling save(), but only after the save() is complete as part of the form save... How can I access the new values of this field in the override save() ?

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  • Django comparing model instances for equality

    - by orokusaki
    I understand that, with a singleton situation, you can perform such an operation as: spam == eggs and if spam and eggs are instances of the same class with all the same attribute values, it will return True. In a Django model, this is natural because two separate instances of a model won't ever be the same unless they have the same .pk value. The problem with this is that if a reference to an instance has attributes that have been updated by middleware somewhere along the way and it hasn't been saved, and you're trying to it to another variable holding a reference to an instance of the same model, it will return False of course because they have different values for some of the attributes. Obviously I don't need something like a singleton , but I'm wondering if there some official Djangonic (ha, a new word) method for checking this, or if I should simply check that the .pk value is the same with: spam.pk == eggs.pk I'm sorry if this was a huge waste of time, but it just seems like there might be a method for doing this, and something I'm missing that I'll regret down the road if I don't find it.

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  • Alternate datasource for django model?

    - by slypete
    I'm trying to seamlessly integrate some legacy data into a django application. I would like to know if it's possible to use an alternate datasource for a django model. For example, can I contact a server to populate a list of a model? The server would not be SQL based at all. Instead it uses some proprietary tcp based protocol. Copying the data is not an option, as the legacy application will continue to be used for some time. Would a custom manager allow me to do this? This model should behave just like any other django model. It should even pluggable to the admin interface. What do you think? Thanks, Pete

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  • Django database caching

    - by hekevintran
    The object user has a foreign key relationship to address. Is there a difference between samples 1 and 2? Does sample 1 run the query multiple times? Or is the address object cached? # Sample 1 country = user.address.country city = user.address.city state = user.address.state # Sample 2 address = user.address country = address.country city = address.city state = address.state

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  • Django - Threading in views without hanging the server

    - by bobthabuilda
    One of my applications in my Django project require each request/visitor to that instance to have their own thread. This might sound confusing, so I'll describe what I'm looking to accomplish in a case based scenario, with steps: User visits application Thread starts Until the thread finishes, that user's server instance hangs Once the thread completes, a response is delivered to the user Other visitors to the site should not be affected by any other users using the application How can I accomplish something like this? If possible, I'd like to find a lightweight solution.

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  • raw_id_fields for modelforms

    - by nbv4
    I have a modelform which has one field that is a ForeignKey value to a model which as 40,000 rows. The default modelform tries to create a select box with 40,000 options, which, to say the least is not ideal. Even more so when this modelform is used in a formset factory! In the admin, this is easiely avoidable by using "raw_id_fields", but there doesn't seem to be a modelform equivalent. How can I do this? Here is my modelform: class OpBaseForm(ModelForm): base = forms.CharField() class Meta: model = OpBase exclude = ['operation', 'routes'] extra = 0 raw_id_fields = ('base', ) #does nothing The first bolded line works by not creating the huge unwieldy selectbox, but when I try to save a fieldset of this form, I get the error: "OpBase.base" must be a "Base" instance. In order for the modelform to be saved, 'base' needs to be a Base instance. Apparently, a string representation of a Base primary key isn't enough (at least not automatically). I need some kind of mechanism to change the string that is given my the form, to a Base instance. And this mechanism has to work in a formset. Any ideas? If only raw_id_fields would work, this would be easy as cake. But as far as I can tell, it only is available in the admin.

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  • Can I filter a django model with a python list?

    - by Rhubarb
    Say I have a model object 'Person' defined, which has a field called 'Name'. And I have a list of people: l = ['Bob','Dave','Jane'] I would like to return a list of all Person records where the first name is not in the list of names defined in l. What is the most pythonic way of doing this?

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  • IntegrityError: foreign key violation upon delete

    - by Lukasz Korzybski
    I have Order and Shipment model. Shipment has a foreign key to Order. class Order(...): ... class Shipment() order = m.ForeignKey('Order') ... Now in one of my views I want do delete order object along with all related objects. So I invoke order.delete(). I have Django 1.0.4, PostgreSQL 8.4 and I use transaction middleware, so whole request is enclosed in single transaction. The problem is that upon order.delete() I get: ... File "/usr/local/lib/python2.6/dist-packages/django/db/backends/__init__.py", line 28, in _commit return self.connection.commit() IntegrityError: update or delete on table "main_order" violates foreign key constraint "main_shipment_order_id_fkey" on table "main_shipment" DETAIL: Key (id)=(45) is still referenced from table "main_shipment". I checked in connection.queries that proper queries are executed in proper order. First shipment is deleted, after that django executes delete on order row: {'time': '0.000', 'sql': 'DELETE FROM "main_shipment" WHERE "id" IN (17)'}, {'time': '0.000', 'sql': 'DELETE FROM "main_order" WHERE "id" IN (45)'} Foreign key have ON DELETE NO ACTION (default) and is initially deferred. I don't know why I get foreign key constraint violation. I also tried to register pre_delete signal and manually delete shipment objects before delete on order is called, but it resulted in the same error. I can change ON DELETE behaviour for this key in Postgres but it would be just a hack, I wonder if anyone has a better idea what's going on here. There is also a small detail, my Order model inherits from Cart model, so it actually doesn't have id field but cart_ptr_id and after DELETE on order is executed there is also DELETE on cart, but it seems unrelated? to the shipment-order problem so I simplified it in the example.

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  • In Rails, how should I implement a Status field for a Tasks app - integer or enum?

    - by Doug
    For a Rails 3.0 Todo app, I have a Tasks model with a Status field. What's the best way to store the Status field data (field type) and still display a human-readable version in a view (HTML table)? Status can be: 0 = Normal 1 = Active 2 = Completed Right now I have this: Rails Schema Here: create_table "tasks", :force = true do |t| t.integer "status", :limit = 1, :default = 0, :null = false Rails Model Here: class Task < ActiveRecord::Base validates_inclusion_of :status, :in => 0..2, :message => "{{value}} must be 0, 1, or 2" Rails View Here: <h1>Listing tasks</h1> <table> <tr> <th>Status</th> <th>Name</th> <th></th> <th></th> <th></th> </tr> <% @tasks.each do |task| %> <tr> <td><%= task.status %></td> <td><%= task.name %></td> <td><%= link_to 'Show', task %></td> <td><%= link_to 'Edit', edit_task_path(task) %></td> <td><%= link_to 'Delete', task, :confirm => 'Are you sure?', :method => :delete %></td> </tr> <% end %> </table> Requirements Store a Task's status in the db such that the values are easily localizable, i.e. I'm not sure I want to store "normal", "active", "completed" as a string field. Solution must work with Rails 3.0. Questions: Should I store the field as an integer (see above)? If so, how do I display the correct human readable status in an HTML table in my Rails view, e.g. show "Active" instead of "1" in the HTML table. Should I use an enum? If so, is this easy to localize later? Should I use straight strings, e.g. "Normal", "Active", "Completed" Can you provide a quick code sample of the view helper, controller or view code to make this work?

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