My database is setup something like.
class comments(models.Model):
min = models.FloatField()
max = models.FloatField()
comment = models.CharField(max_length=255)
In my view, I grab a float value from the user. I want to take that value use the Min/Max as parameters and if that float value is between the Min/Max, display the comment that's associated to it. At times there might be more then 1 match, however for now I cant even figure out how to do the first step.
Use the filter() method of a model manager with a combination of __lte/__gte lookups:
def comments(request):
value = float(request.GET['value'])
return render(request, 'comments.html',
{'comments': comments.objects.filter(min__lte=value,
max__gte=value)})
And then in the comments.html:
{% for comment in comments %}
<div>{{ comment.comment }}</div>
{% endfor %}
Related
I'm trying to get a list of latest 100 posts and also the aggregated count of approved, pending, and rejected posts for the user of that post.
models.py
class BlogPost(models.Model):
POST_STATUSES = (
('A', 'Approved'),
('P', 'Pending'),
('R', 'Rejected')
)
author = models.ForeignKey(User)
title = models.CharField(max_length=50)
description = models.TextField()
status = models.ChoiceField(max_length=1, choices=POST_STATUSES)
views.py
Now I'm getting the the aggregated count like so, but I'm confused on how to merge the count with the title of the posts
top_post_users = list(BlogPost.objects.values_list('user_id', flat=True))[:100]
users = User.objects.filter(pk__in=top_post_users).annotate(approved_count=Count(Case(When(user_posts__status="A", then=1),output_field=IntegerField()))).annotate(pending_count=Count(Case(When(user_posts__status="P", then=1),output_field=IntegerField()))).annotate(reject_count=Count(Case(When(user_posts__status="R", then=1),output_field=IntegerField())))
users.values('approved_count', 'pending_count', 'reject_count')
This is the result I want:
Title Of Post, Author1, 10, 5, 1
Title Of Post2, Author2, 7, 3, 1
Title Of Post3, Author1, 10, 5, 1
How can I merge the returned counts with the titles?
I know I could use a for loop and append each one, but efficiency wise I don't think this is the right way to do it. Is there a more efficient way using django database ORM?
I've tried this
users.values('title', approved_count', 'pending_count', 'reject_count')
...and that works, but it returns more than the latest 100 posts, so I think it's getting all the posts for those users and the aggregated count.
Ultimately, you want a list of BlogPosts:
main_qs = BlogPost.objects
# add filters, ordering etc. of the posts
and you want to display not only the authors next to the title of the post but also enrich the author information with the annotated counts.
from django.db.models import OuterRef, Subquery, Count
# you need subqueries to annotate the blog posts
base_sub_qs = BlogPost.objects.filter(author__pk=OuterRef('author__pk'))
# add subqueries for each count
main_qs = main_qs.annotate(
user_approved_count=Subquery(base_sub_qs.filter(status="A").annotate(
c=Count('*')).values('c'), output_field=IntegerField()),
user_pending_count=Subquery(base_sub_qs.filter(status="P").annotate(
c=Count('*')).values('c'), output_field=IntegerField()),
user_rejected_count=Subquery(base_sub_qs.filter(status="R").annotate(
c=Count('*')).values('c'), output_field=IntegerField()),
)
You can then access these in your template:
{% for post in posts %}
{{ post.title }}
{{ post.author.get_full_name }}
approved: {{ post.user_approved_count }}
pending: {{ post.user_pending_count }}
rejected: {{ post.user_rejected_count }}
{% endfor %}
Documentation: https://docs.djangoproject.com/en/2.1/ref/models/expressions/#subquery-expressions
I would like to automatically retrieve the name of the column with a for loop.
If I know the name of the columns I can write the template in this way:
<ul>
{% for co in team %}
<li>{{ co.name }}</li>
<li>{{ co.team}}</li>
<li>{{ co.sport}}</li>
{% endfor %}
</ul>
But in my present case, I do not know the names of the columns of my table. How can I display them?
Thank you
You can obtain the fields of a model with:
fields = Model._meta.get_fields()
This is a tuple of Field [GitHub] objects. These Field objects have a name attribute, so we can obtain the field names with:
from operator import attrgetter
field_names = map(attrgetter('name'), Model._meta.get_fields())
In case we do not know what the model is, we can obtain a reference to the model of a model instance with type(..):
fields = type(some_instance)._meta.get_fields()
All this logic however does not really belong in the Django template, but in the view (by design, Django templates are a bit restrictive to prevent writing business logic in the template). We can thus pass a list of field names to the template:
def some_view(request):
teams = Team.objects.all()
field_names = [f.name for f in Team._meta.get_fields()]
return render(request, 'some_template.html',
{'teams': teams, 'field_names': field_names}
)
If you however want to print the values of these teams, then this will still not work, since we can not easily get an arbitrary attribute in a template. Then we can again shift some processing to the view:
from operator import attregetter
def some_view(request):
teams = Team.objects.all()
field_names = [f.name for f in Team._meta.get_fields()]
atgetters = [attrgetter(fn) for fn in field_names]
rows = [[ag(team) for ag in atgetters] for team in teams]
return render(request, 'some_template.html',
{'teams': teams, 'field_names': field_names, 'data': data}
)
So here data is a list containing lists, such that data[i][j] contains the value for a field with name field_name[j] for teams[i].
I have created a checkbox for content filtering of products based on category.So when the user clicks on any checkbox only the books with that category should be shown.In the view I am passing the value of checkbox field(category name) obtained from the template but upon filtering, the foreign key is expecting pk(id) instead of field value.I am getting error like this,invalid literal for int() with base 10: '<category name>'.So is it possible to make foreign key accept value instead of id?
Models.py,
class Add_cat(models.Model):
category = models.CharField("Name",max_length=25,unique=True)
def __unicode__(self):
return u'{0}'.format(self.category)
class Add_prod(models.Model):
book = models.CharField("Book Name",max_length=40)
author = models.CharField("Author",max_length=30)
price = models.PositiveIntegerField("Price")
image = models.ImageField(upload_to='images',null=True)
cat = models.ForeignKey(Add_cat,on_delete=models.PROTECT)
Template file,
{% for i in products %}
<input type="checkbox" name="cat_name" value="{{i.cat}}">{{i.cat}}<br>
{% endfor %}
Views.py,
def welcome_user(request):
if 'cat_name' in request.GET:
filter_category = request.GET.get('cat_name')
my_products = Add_prod.objects.filter(cat__in = filter_category)
context = { "products":my_products}
else:
my_products = Add_prod.objects.all()
context = { "products":my_products}
return render(request,"welcome-user.html",context)
You can check in the category field itself:
my_products = Add_prod.objects.filter(cat__category__in=filter_category)
Have a look at the documentation on how this works.
Above, is only applicable if filter_category is a list. If it is a string you can filter like following:
my_products = Add_prod.objects.filter(cat__category=filter_category)
There are two things wrong with your code
You need to look up the field rather than the foreign key
By using __in you are looking the category is equal to any one of the characters in the filter_category.
Hence to fix, use the field lookup and remove the __in
Add_prod.objects.filter(cat__category=filter_category)
You can try this,it will help you:
Add_prod.objects.filter(cat__category = filter_category)
I am using django here is my model:
class Location(models.Model):
id = models.IntegerField(primary_key=True)
name = models.CharField(max_length=50)
altitude = models.IntegerField(max_length=10000)
area = models.ForeignKey('Area')
def __str__(self):
return str(self.area) + ':' + str(self.name)
#measurement.id value date location
class Measurement(models.Model):
id = models.IntegerField(primary_key=True)
value = models.FloatField(max_length=50)
data = models.DateTimeField()
location = models.ForeignKey('Location')
def __str__(self):
return "measurement#"+str(Location.objects.filter(id=self.id))
My HTML page is showing {'value__avg': 46.26524716693248} when it should just show 46.265.
Heres my function:
#property
def average_measurement(self):
locations = Location.objects.filter(area__name=self.name)
return Measurement.objects.filter(location__in=locations).aggregate(Avg('value'))
so how do I get the ugly part out?
aggregate() returns a dictionary where the key is combined from the grouping keys and grouping function name, you can just get the value by key:
return Measurement.objects.filter(location__in=locations).aggregate(Avg('value'))["value__avg"]
Or, if needed, you can also do that in the template using the dot-notation:
{{ obj.average_measurement.value__avg }}
You can also preset the key name with your own value:
return Measurement.objects.filter(location__in=locations).aggregate(my_average=Avg('value'))
Then, you would access it as:
{{ obj.average_measurement.my_average }}
That's not the ugly part, it's expected output and you need to understand what does the output mean. When you do django Aggregation, it returns a dictionary-like object with your aggregation criteria as keys and results as values.
What you need to do is to access it like a dictionary in template to extract the values:
{% for item in items %}
{{ item.value__avg|floatformat:3 }}
{% endfor %}
Check django doc about what is the lookup sequence for dot in template.
Also checkout django doc about aggreate function call.
Also checkout django doc about floatformat template filter.
I have a content that I'd like to rate on multiple criteria.
Imagine this kind of model:
class Content(models.Model):
name = models.CharField(max_length=50)
class Criterion(models.Model):
name = models.CharField(max_length=50)
content = models.ForeignKey(Content)
class ContRate(models.Model):
user = models.ForeignKey(User, help_text="Who rated ?")
crit = models.ForeignKey(Criterion)
rate = models.DecimalField()
The user has a page displaying the content.
From this page, he can also rate the content on the criteria set
The rating will be done with Ajax.
Now I'm trying to implement the view & the template
view.py
#...
def viewcont(request, content_id):
"""The user can view a content & rate it"""
content = get_object_or_404(Content, pk=content_id)
RateFormSet = modelformset_factory(ContRate)
formset = RateFormSet(queryset=ContRate.objects.filter(content=content, user=request.user))
objs = {
'content': content,
'forms': formset,
}
return render_to_response('content/content_detail.html', objs
, context_instance=RequestContext(request)
)
#...
content_detail.html
<!-- ... -->
<div id="rating">
<ul>
{% for crit in content.crit_set.all %}
<li>
{{ crit }}
<div class="rateit"
data-rateit-value="the_actual_rating_if_already_there"
data-rateit-ispreset="true"
crit-id="{{ crit.id }}"></div>
</li>
{% endfor %}
</ul>
</div>
<!-- ... -->
Now how can I use the forms formset to display the actual rates ?
And how can I draw an empty form to be posted by Ajax from any clicked star ?
(I know the javascript/jQuery part)
Not sure what the point of the formset is here. The rates are all available via the criteria object, using the reverse foreign key to ContRate in exactly the same way as you've done from Criteria to Content.
To make this as efficient as possible, you probably want to get the relevant ratings in the view and bring them together into a single datastructure:
content = get_object_or_404(Content, pk=content_id)
criteria = content.criteria_set.all()
user_ratings = ContRate.objects.filter(content=content, user=request.user)
ratings_dict = dict((c.crit_id, c.rate) for c in user_ratings)
for crit in criteria:
crit.user_rating = ratings_dict.get(crit.id)
Now you can pass criteria directly to your template, and there you can iterate through it to show the user_rating for each one.
(Final point: "criteria" is plural, the singular is "criterion". :-)