In model:
class Example
text
class Share
example (foreign_key)
user (foreign_key)
In view:
def page:
items = Example.objects.get(user=user)
user_shares = Example.objects.get(user=user)
return render(page.html, {'items': items, 'user_shares': user_shares})
In the template I can show items in rows. But for the shared ones I want to put for example additional buttons.
How can I use something like {% if item in shares %} in for loop? Or do you have better ideas?
in the template:
{% for item in items %}
<td>{{item.text}}</td>
{%if item.shares.count > 0 %}
<td><!-- additional buttons here --></td>
{% endif %}
{% endfor %}
you need to modify the ForeignKey in the Example model:
class Share(models.Model):
example = models.ForeignKey(Example, related_name='shares')
...
Hope this helps.
Related
I am using Django 2.0.1, and I have the following code:
Models.py:
class Category(models.Model):
category_name = models.CharField(max_length=50)
class CategoryItems(models.Model):
category_name = = models.ForeignKey(Categories, related_name='categoriesfk', on_delete=models.PROTECT)
item_name = models.CharField(max_length=50)
item_description = models.CharField(max_length=100)
Thereafter my views.py:
def data(request):
categories_query = Categories.objects.all()
category_items_query = CategoriesItems.objects.all()
return render_to_response("data.html",
{'categories_query': categories_query,'category_items_query': category_items_query}
In the template I'm trying to display all items for each category, for example, suppose there are 4 categorizes, e.g. Bicycle, then it display all items belonging to that category only. For example, as follows:
Category 1:
Category_Item 1,
Category_Item 2,
Category_Item 3,
and so on ...
Category 2:
Category_Item 1,
Category_Item 2,
Category_Item 3,
and so on ...
I have tried to write so many different for-loops, but they just display all items, I need it to show items only for that category, then for loop to next category and show items for that.
You don't need your category_items_query variable, just category_query:
{% for category in category_query %}
<b>{{ category.category_name }}</b><br />
{% for item in category.categoriesfk.all %}
{{ item.item_name }}<br />
{% endfor %}
{% endfor %}
Your related_name of categoriesfk is weird, it'd make more sense to be something like items.
What you need is two for loops with an if to check if the second loop should belong to the first.
Try this:
{% for category in categories_query %}
{% for category_item in category_items_query %}
{% if category_item.category_name == category %}
{# do something with category_item #}
{% endif %}
{% endfor %}
{% endfor %}
I believe it would be more clear if you named the ForeignKey in CategoryItems to just "category", instead of "category_name", since this field will have the category itself, not just it's name. Your "if" would then be more readable and make more sense:
{% if category_item.category == category %}
Hope it helps.
A few things,
Since your model name is already Category, your field names should be like name instead of category_name.
Model names must be singular, so it should beCategoryItem instead of CategoryItems
When you do a model_name.objects.all(), you do not get a query but a Queryset, make your variable names such that they describe what they do. Currently, categories_query is wrong. You could instead use category_qs.
Now, coming to your question, you require two for loops. One to loop through the categories and then one to loop through items in a particular category.
Something like,
for category in category_qs:
for item in category:
# Do something with item
You have the basic idea here, now you can convert it to real working code. Good luck!
Grouping data in template is not best idea as template should be logic free,
also good idea would be to use database capabilities and use select_related to query out related set
category_data = Category.objects.select_related('item').all()
afterwards you could do following in template
{% for category in category_data %}
{# print category #}
{% for item in category.items %}
{# print item #}
{% endfor %}
{% endfor %}
Django has a built-in regroup template tag for this functionality.
{% regroup category_items_query by category_name as categoryname_list %}
{% for category in categoryname_list %}
<strong>{{ category.grouper }}</strong><br>
{% for item in category.list %}
{{ item.item_name }}: {{ item.item_description }}<br>
{% endfor %}
{% endfor %}
You have to order your CategoryItems for this functionality to work.
category_items_query = CategoriesItems.objects.all().order_by('category_name')
In a Django queryset how can I tell if the list item I'm on (when iterating) is the list item that has a certain attribute.
Example: I order a queryset by:
MyModel.objects.all().order_by('-featured', '-created_at')
So, all objects which are featured first by their appropriate time and then all non-featured items sorted by time properly as well.
When iterating in the template I want to be able to tell if I've hit the last "featured" item in the dual-ordering (such that featured = True).
Example usage: If last item -> display banner separating featured / non-featured -> continue iterating displaying non-featured after banner.
{% for object in object_list %}
# display object
{% if last item with attribute %}
# display banner
{% endif %}
{% endfor %}
I know I can do another queryset to get the count, but that's an extra query I'd like to avoid.
You can group the items in the queryset using itertools.groupby before passing it to the template. Then you'll show the banner when the group key changes from True to False:
from itertools import groupby
qs = MyModel.objects.all().order_by('-featured', '-created_at')
grouped_qs = groupby(qs, lambda x: x.featured)
And then in your template:
{% for k, g in grouped_qs %}
{% if not k %}
<!- show banner -->
{% endif %}
{% for model_obj in g %}
<!- do something with model_obj -->
{% endfor %}
{% endfor %}
I am trying to create a dynamic form, with a varying number of CharFields. I want to be able to display them at will in semi-arbitrary places in my form. My approach was to create an iterable function that fielded the right self.fields[INDEX]. However, when I do this, I literally see this:
<django.forms.fields.CharField object at 0x80bae6be0>
<django.forms.fields.CharField object at 0x80bae6f98>
<django.forms.fields.CharField object at 0x80bae6da0>
How do I make a CharField() render as expected?
My code is below:
class ImplementationForm(forms.ModelForm):
"""
Specifies the implementation of a given control.
"""
class Meta:
model = Implementation
fields = ['implemented', 'scope', 'separate']
def __init__(self, *args, **kwargs):
control = kwargs.pop('control')
super(ImplementationForm, self).__init__(*args, **kwargs)
self.fields['separate'].widget.attrs.update({'class': 'separate'})
self.fields['scope'].widget.attrs.update({'class': 'scope'})
for substatement in control.substatement.all():
self.fields['statement_%s'%substatement.pk] = forms.CharField()
def subfield(self):
print("Comes herE")
for index in self.fields:
if index[:10] == 'statement_':
yield self.fields[index]
The template basically does this:
{% for x in myform.subfield %} {{ x }} {% endfor %}
What you are looking for is the form's BoundFields. e.g. {{ form.email }}
You are iterating over the Field instances (not the form's BoundField instances that wraps the Field Instances) e.g. {{ form.field.email }}.
This is why you are getting the
<django.forms.fields.CharField object at 0x80bae6da0>
result from your template. See: https://stackoverflow.com/a/671305/3035260
Also see django's documentation: https://docs.djangoproject.com/en/1.10/ref/forms/api/#django.forms.BoundField
Try this dirty way (See my edit below for a much better solution):
{# Iterate over your list of field instances #}
{% for x in myform.subfield %}
{# Find the matching BoundField instance #}
{% for field in myform %}
{% if field.field == x %}
{# Matching BoudField instance found, display it. #}
{{ field }}
{% endif %}
{% endfor %}
{% endfor %}
Edit:
Just came across a better (less dirty) approach:
A Field has a
get_bound_field(self, form, field_name)
method according to the docs: https://docs.djangoproject.com/en/1.10/_modules/django/forms/fields/#Field.get_bound_field
So, in your subfield method in the last line (The 'yield' line), try this:
yield self.fields[index].get_bound_field(self, index)
Then, your template will remain the same:
{% for x in myform.subfield %} {{ x }} {% endfor %}
and everything should work as you intended.
OK, so again there is likely a "simple" solution to this, but I am a beginner and nothing seems simple to me.
I have a view and a template that shows the attributes of an instance of a Car class that I have modeled. This Car class has a ManyToMany relationship with my custom User class. The template that show the attributes of a given instance of Car has many variables. The view for each Car works fine. Here is what I can't get to work:
I have a user profile page for each instance of User. From that page, I want to show the attributes of each Car that a particular User has "favorited." I am unable to figure out how to do this.
I have tried the {% include %} tag to include a snippet of the Car template and then use a for statement to iterate through the favorite set of the User. In theory, this would populate the User page with each Car that they have "favorited" and show its attributes. However, I do not know how to pass the {% include %} tag the proper context so the attributes are populated correctly for each instance of Car. Is this possible?
Is there a simpler way to do it that I am just overlooking?
Any help is appreciated. Thanks!
Use the {% include ... with ... %} syntax:
{% for car in user.favorite_cars.all %}
{% include "car.html" with name=car.name year=car.year %}
{% endfor %}
Another alternative is the {% with %} tag:
{% for car in user.favorite_cars.all %}
{% with name=car.name year=car.year %}
{% with color=car.color %}
{% include "car.html" %}
{% endwith %}
{% endwith %}
{% endfor %}
UPDATE: If data for the template can't be obtained from the Car model then you have to use the custom inclusion tag:
from django import template
register = template.Library()
#register.inclusion_tag('car.html')
def show_car(car):
history = get_history_for_car(car)
return {'name': car.name, 'history': history}
And the in the template:
{% load my_car_tags %}
{% for car in user.favorite_cars.all %}
{% show_car car %}
{% endfor %}
I am new to Django and I've been impressed so far by its capabilities. I am playing with more complex models and I am have problem to use them properly. Using Django 1.3, I am trying to write a summary page which would present the three models below with the following structure. In other words, a list of trips with their destinations and activities.
Trip 1
Destination 1
Destination 2
Activity 1
Trip 2
Destination 1
Activity 2
Models
Trip <-> TripDestination <-> Destination (a trip can have multiple destinations)
Activity -> Trip, Activity -> Destination (an activity is defined for a trip at a specific location/destination)
class Destination(models.Model):
city_name=models.CharField()
class Trip(models.Model):
departing_on=models.DateField()
returning_on=models.DateField()
destinations=models.ManyToManyField(Destination)
class Activity(models.Model):
destination=models.ForeignKey(Destination, null=False)
trip=models.ForeignKey(Trip, null=False)
I am trying to write a view which would generate a page with the structure presented above. The main problem I am having right now is to display the activities for a specific trip and destination. As you can see in the code below, I am building a dictionary and I doubt it is the right thing to do. In addition, the view becomes
View
def list_trip(request, template_name = 'trip-list.html'):
trips = Trip.objects.all()
# Build a dictionary for activities -- Is this the right thing to do?
activities = Activity.objects.filter(trip__in=trips)
activities_by_trips = dict()
for activity in activities:
if activity.trip_id not in activities_by_trips:
activities_by_trips[activity.trip_id] = dict()
if activity.destination_id not in activities_by_trips[activity.trip_id]:
activities_by_trips[activity.trip_id][activity.destination_id] = []
activities_by_trips[activity.trip_id][activity.destination_id].append(activity)
return render_to_response(template_name, {
'page_title': 'List of trips',
'trips': trips,
'activities_by_trips': activities_by_trips,
})
Template
{% block content %}
{% for trip in trips %}
{{ trip.id }} - {{ trip.name }}
{% for destination in trip.destinations.all %}
{{ destination.city_name }}
** This is terrible code -- How to fix that **
{% for key, value in activities_by_trips|dict_lookup:trip.id %}
{% if value %}
{% for key_prime, value_prime in value|dict_lookup:destination.id %}
{{ value_prime.description }}
{% endfor %}
{% endif %}
{% endfor %}
{% endfor %}
{% endfor %}
{% endblock %}
In brief, can someone please help me to get a summary of all the trips and activities? What's the best way to accomplish that? Is the model correct?
Thanks!
There is plenty of room for improvement. By using through on ManyToManyField you can explicitly define the join table, which we can conveniently consider as a single visit to a city during a particular trip. During that visit we had activities, so activity should have a foreignkey to a visit.
For each foreignkey in a table, Django will add API convenience manager for sets of objects on the opposite side of the relationship. Destination will have a visit_set, but so will Trip. Similarly, because of visit foreignkey in Activity each visit will have an activity_set.
First start with the models:
from django.db import models
# Create your models here.
class Destination(models.Model):
city_name=models.CharField(max_length=50)
class Trip(models.Model):
departing_on=models.DateField()
returning_on=models.DateField()
destinations=models.ManyToManyField(Destination, through='Visit')
class Visit(models.Model):
destination=models.ForeignKey(Destination)
trip=models.ForeignKey(Trip)
class Activity(models.Model):
name=models.CharField(max_length=50)
visit=models.ForeignKey(Visit)
Then lets change list_trip a bit, added print_trip for clarity of what is going on in template:
def list_trip(request, template_name = 'trip-list.html'):
return render_to_response(template_name, {
'page_title': 'List of trips',
'trips': Trip.objects.all(),
})
def print_trips():
for trip in Trip.objects.all():
for visit in trip.visit_set.select_related().all():
print trip.id, '-', visit.destination.city_name
for act in visit.activity_set.all():
print act.name
And finally the improved template:
{% block content %}
{% for trip in trips %}
{{ trip.id }} - {{ trip.name }}
{% for visit in trip.visit_set.select_related.all %}
{{ visit.destination.city_name }}
{% for act in visit.activity_set.all %}
{{ act.name }}
{% endfor %}
{% endfor %}
{% endfor %}
{% endblock %}
There is still some more room for improvement performance wise. Notice I used select_related. That will prefetch all destinations at the time visits are fetched, so that visit.destination.city_name will not incur another db call. However this doesn't work for reverse ManyToMany relationships (in our case all members of activity_set). Django 1.4 will come out with new method called prefetch_related which will resolve that as well.
In the mean time, read up on Efficient reverse lookups for an idea how to even further reduce the number of DB hits. In the comments few readily available solutions are mentioned as well.