Incorporating "Like Post" feature

Question

Hey so I am making a color scheme posting site where people can register and post color schemes they come up with. So far everything is working great, the only thing I have left to do is add a "Like Post" feature. I'm wondering what the best way to implement this would be.

I have two ideas on how this could be done, the first is add an additional field to both the ColorSet (posts) and the User models (for the user model I would set up a new model with a OneToOne relationship to add onto the User model) which would record users that have each single post, and which posts each user has liked to keep track of everything.

So this could look something like this:

from django.db import models
from django.core.urlresolvers import reverse
from django.conf import settings

from django.contrib.auth import get_user_model
User = get_user_model()

# Create your models here.
class ColorSet(models.Model):
    user = models.ForeignKey(User,related_name='colorset')
    published_date = models.DateTimeField(auto_now_add=True)
    name = models.CharField(max_length=50,blank=False)
    color_one = models.CharField(max_length=6,blank=False,default='cccccc')
    color_two = models.CharField(max_length=6,blank=False,default='ffffff')
    color_three = models.CharField(max_length=6,blank=False,default='e5e5e5')
    color_four = models.CharField(max_length=6,blank=False,default='f0f0f0')
    color_five = models.CharField(max_length=6,blank=False,default='bababa')
    liked_by = models.IntegerField(blank=True)

    def publish(self):
        self.save()

    def get_absolute_url(self):
        return reverse('index')

    def __str__(self):
        return self.name

user model:

from django.db import models
from django.contrib.auth.models import User

# Create your models here.
class UserStats(models.Model):
    user = models.OneToOneField(User)

    liked_sets = models.IntegerField(blank=True)

    def __str__(self):
        return self.user.username

In this first option I would have the new model fields (liked_sets and liked_by) be equal to lists containing the ok's of all the Color Sets each user has liked and all the users who have liked each post respectively.

The other way that I'm thinking about would be to just create an entirely new model that tracks the likes for each color set post (not totally sure how this model would look yet exactly).

Aside from which is easier, I wondering which makes more sense from a technical standpoint? Will one of these two options take up more space or create heavier server load?

Thanks for the help.

Answer 1

As far as I understand your problem, it can be broken in two parts.

1. Maintaining the total number of likes on a model ColorSet.

2. Keeping the track of all those users who liked a single instance of ColorSet.

Now if I understand your problem correctly(correct me if I'm wrong), when you say:

new model fields (liked_sets and liked_by) be equal to lists containing the ok's of all the Color Sets each user has liked and all the users who have liked each post respectively.

you intend to create a field in your database which would simply store a list of pks of all the people who've liked a ColorSet model instance. Even if you don't intend to do that, still an IntegerField to store such information is(in my humble opinion) somewhat wrong.

Now why you wouldn't want to do that? It's because relational databases are made to recognize the relations between tuples of information and enhance the processing by creating relations. That is why we use relations like OneToOneField and ForeignKey. They make the processing way faster. If we were to simply store the pk values in a Field, further search them in our database to retrieve information, that would be something really slow.

Now I suppose what you are looking for is ManyToManyField.

In your problem, you will simply map the ManyToManyField it to the User model.

It would look something like:

class ColorSet(models.Model):
    user = models.ForeignKey(User,related_name='colorset')
    published_date = models.DateTimeField(auto_now_add=True)
    name = models.CharField(max_length=50,blank=False)
    color_one = models.CharField(max_length=6,blank=False,default='cccccc')
    color_two = models.CharField(max_length=6,blank=False,default='ffffff')
    color_three = models.CharField(max_length=6,blank=False,default='e5e5e5')
    color_four = models.CharField(max_length=6,blank=False,default='f0f0f0')
    color_five = models.CharField(max_length=6,blank=False,default='bababa')
    liked_by = models.IntegerField(blank=True)
    #add a simple ManyToManyField which will hold all the users who liked this colorset
    likers = models.ManyToManyField(User , related_name = 'liked_colorsets') 

    def publish(self):
        self.save()

    def get_absolute_url(self):
        return reverse('index')

    def __str__(self):
        return self.name

and remove your UserStats model to

Now use the following code outline structure to access the information from the database.

1) To get the ColorSets liked by a User:

#obtain any user model object; for example: user_object = User.objects.get(...)
user_object.liked_colorsets.all()
#a queryset with all the liked colorsets is returned.

2) To get the Users who liked a ColorSet:

#obtain any colorset model object; for example: colorset_object = ColorSet.objects.get(...)
colorset_object.likers.all()
#a queryset with all the Users who liked this colorset is returned.

One more thing that I would like to add here. After a User likes a ColorSet, you would obviously want to add this User to the likers field in your ColorSet model(and increment the liked_by field; I assume you'll manage that). To add a User in the likers field:

#obtain any colorset model object; for example: colorset_object = ColorSet.objects.get(...)
#obtain the user model object of the user who liked this colorset in user_object
#and do 
colorset_object.likers.add(user_object)

Read more about adding the models in ManyToManyField here in docs.

Hope this helps. Thanks.