I'm a beginner in Django. When developing an app, I want to fulfill the following functionality: There is some pictures in one webpage. A user can 'like' a picture by clicking a button bellow it. But one user can only like a specific picture once.
Now there seem two methods to do this.
1) Set an attribute in the session. So I when a user click a button, I can check if he has already 'liked' this picutre according to this session.
2) Add a new field in my user's model to record which pictures he has 'liked'.
Then I don't know which one to use. My questions are as follows:
For method (1), session can expire after some time (e.g. 2 weeks).
So for a user who revisits my website after 2 weeks, is it true that
I can not prevent him from re-liking the picture he's already 'liked'
before?
If I want to have access to the info about which pictures a user
has 'liked', is it true that I can only use method (2) to store this
information?
Thanks a lot!
If you want the "favorites" to persist across multiple sessions, then yes, you need to store the data somewhere that isn't volatile. A simple solution is to use a separate model, a LikedPicture for example:
class LikedPicture(models.Model):
user = models.ForeignKey(User, db_index=True)
picture = models.ForeignKey(Picture)
Session expired? No problem, just get the ones they've liked from the model. You could take it a step further and make the related model generic, so you don't have to make a separate model to hold each association, if you have several different models you're going to associate similarly.
Want to make sure the user only favorites something once? Django makes this ridiculously easy with get_or_create():
favorited_picture, created = FavoritedPicture.objects.get_or_create(user=user,
picture=picture, defaults={'user': user, 'picture': picture})
I find this method to be much more straightforward than trying to maintain a comma-separated-field on a model to store the ids of the favorited things.
Related
IS it possible to save the Form data from a Guest / Visitor in the DB?
MY Idea is to display a form where a User is presented with the questions. The answers are unique for each user to I want to map the answers to the Users using a Foreign Key. Problem is that when I want to map it using ForeignKey it says that the answers come from a Null User. I ant my visiting users to access the website also.
I have saved the Data in sessions and then used it
I Do not want to use that approach
Is there any way so that my users can access the website without saving the data in the website. Anyways, the flow of code deletes the answers data from DB once the work is done.
It is not about getting the work done but exploring and getting knowledge.
I can not do
class AnsModel(model.Model):
user=models.ForeignKey(User, on_delete=models.CASCADE)
ans=models.CharField(max_length=1024)
What would be the Model and View for this?
I have been working around this problem. I have a user submitting a HTML form lets say to list their hotel on my website. I need to review this form before i add it into my hotels model to be published.
One approach i have worked on is to use a requests model where this form can be stored and later using django admin action write a custom action to add/remove the request. In case of acceptance i copy the details to my hotels model else it sends an email or a notification back to user.
Second approach is simply using django action on hotels model where the request is sent to approve it or reject it. In this case i want to know if thats possible where a data point doesn't get written to database until it's been accepted by admin. If yes how can i do that?
Finally, these details are displayed on my main page and search page for users to book these places.
If there is a better and effective way to do it. Please share that.
Thanks in advance. If something isn't clear i can answer your specific questions in the comments below 😊.
Have a nice day.
You can have is_published Boolean field in your hotel model and you can default it to false initially. After you inspect the hotel details you can set the is_published field to True from django admin.
So now whenever you are querying for hotels to show on your website. You can query
Hotel.objects.filter(is_published=True)
Django has an authentication and authorization scheme baked in ('django.contrib.auth') as well as modelforms to generate forms for easy input of data into the database.
I'd like to be able to record who created a record, leveraging django.contrib.auth, with the explicit purpose of limiting editing of that same record to just that user and/or people with an "edit" permission. I know that I could use the #user_passes_test decorator to restrict access to editing my record in some fashion, but I don't know what I would compare the request.user.name to in order to determine if the current user originally created that record.
How much of this do I need to roll on my own? Do I need to capture the name author, save it to the model, and then read it - or is there something already in the framework that would do this for me?
And, if I was to attempt to save the author in a field, how would I go about doing that in such a way as to not let the user edit their own credentials?
There are a couple of apps to do something similar, please check https://www.djangopackages.com/grids/g/model-audit/
About the last questions, to prevent the user not to edit its own credentials, you can mark the field with editable=False so it wont appear in the admin or ModelForms.
I have several notifications that can be sent out from my Django application for users. These users are managed with the django.contrib.auth app.
I need to keep track for each whether the user has specified he/she wants to get that notification.
Where should I save this information?
I was going to create my own custom table but I've seen perhaps I can save that information somewhere in the auth module?
User Profiles are a good way to go.
https://docs.djangoproject.com/en/dev/topics/auth/#storing-additional-information-about-users
Set up a model with a OneToOneField to your User object as described and you have easy access to an arbitrary table of extra information.
PS: Heed the note about the fact that profiles are not automatically created. There is an example about how to use a Signal to automatically create one whenever a User is created.
I'm wondering what people's thoughts are on joining models directly to the auth.User object vs to the user's profile model.
I'm storing some different types of models which my user are adding in my app. App users will search for other users via criteria on these models.
On the one hand, I'm thinking that if I join straight to User then I won't need to do request.user.get_profile() each time I need to grab the User's records, and it doesn't presuppose that a User always has a profile (they do in my app at the mo, but still). This leaves the profile model as just containing the user's contact details.
On the other hand, I imagine I'll most likely need values from the Profile (eg name, location) when I'm looking up these other models.
No doubt either will work, so maybe it doesn't matter, but I just wondered what other people's thoughts were.
Thanks!
Ludo.
I would also recommend creating foreign-keys to the User model. It just makes your life simpler when working with the user object in the view, for one. So, you can do things like request.user.foo_set, etc. without having to go through the profile model.
In general: If you want to make your apps reusable, always create foreign keys to User model.
As you already said, in most cases you will need User as well as Profile instance, so to prevent multiple database queries, use cache.
If reusability isn't relevant, create foreign key to Profile and use select_related() to get User instance with single query.