I need to have a nested loop in my Django template, where the outer loop goes through a list of objects, and the inner loop goes through a list of those object id's, and I want to only do something for the id's on the inner list, it never executes however. I think it has something to do with the condition for the if statement, because if I replace it with a true statement it works but it doesn't work as it is now
(I have checked to see that the id's overlap)
{% for outer in outer_obj_list %}
{% for inner_id in inner_id_list %}
{% if outer.id == inner_id %}
// do something
console.log({{inner_id}});
console.log({{outer.id}});
{% endif %}
{% endfor %}
{% endfor %}
Syntax seems correct. I would just verbosely output everything.
Perhaps it should be something like this:
{% for main_obj in main_obj_list %}
main_obj: {{ main_obj }}
{% for obj_id in obj_id_list %}
obj_id: {{ obj_id}}
main_obj: {{ main_obj.id}}
{% if main_obj.id == obj_id %}
// do something
match: {{main_obj.id}} == {{obj_id}} ;
{% endif %}
{% endfor %}
{% endfor %}
Brother I am also face this problem so my clever mind get some clever solution about this problem we can do that with JavaScript easily so we need to run it in JavaScript and then.
{% for outer in outer_obj_list %}
{% for inner_id in inner_id_list %}
if(outer.id == inner_id.id ){
console.log({{inner_id.id}});
console.log({{outer.id}});
//And also if we reserve place in DOM then we can
//change the inner Html of them easily like.
//demo = document.getElementById("demo");
//demo.innerHTML = inner_Id.id or outer.id
}
{% endfor %}
{% endfor %}
Related
I have a for loop in Django template. After that, I check for coincidences. But in some cases, there are might be 3 coincidences. I need to show only the first coincidence. Now, my code returns the name for 3 times, because, there are 3 coincidences
{% for ip in ips %}
{% if d.name == ip.name %}
<strong>{{ d.name}} </strong>
{% endif %}
{% endfor %}
SOLUTION
It is impossible to break forloop in django template, so I decided to change in views.py through queryset distinction of similar names
ips = Point.objects.defer('point').order_by('name').distinct('name')
I don't recommend doing this in Django Template , but in views itself. But if you can't then you can use {{ forloop|break }}.
Something like this :
{% for ip in ips %}
{% if d.name == ip.name %}
{{ forloop|break }}
<strong>{{ d.name}} </strong>
{% endif %}
{% endfor %}
Check the small snippet example here...
I wonder how I can get a specific number of items when i put an if statement inside a for loop
i know we can do {% for i in items|slice ":5"%} to get a number of items but when i do
{% for post in posts %}
{% for img in post_imgs %}
{% if img.link == post.link %}
<img class="class" src="{{img.img.url}}" style="width:100%">
{% endif %}
{% endfor %}
{% endfor %}
there's no way of doing that inside the if tag .. any solution
From this answer:
Changing the state of an object in a Django template is discouraged.
You should probably bite the bullet, calculate the condition
beforehand and pass extra state to the template so you can simplify
the template logic.
So just do your comparisons in python in your view, something like:
post_imgs_filtered = [img for img in post_imgs if img.link == post.link]
And then in your template:
{% for img in post_imgs_filtered|slice ":5" %}
<img class="class" src="{{img.img.url}}" style="width:100%">
{% endfor %}
I have something like the following:
{% for i in "xxxxxxxxx" %}
...
{% if passedInList.*forloop.counter0|add:"1"* %} Do Something {% endif %}
...
{% endfor %}
Obviously the if statement is incorrect. I have been using this method to create index names in forms for quite some time, but have never had to use the for loop counter index in an if statement.
Is this possible? If so, how would I go about doing so?
Thanks!
Try to use a with statement to save the forloop counter in a context variable, like so:
{% with index=forloop.counter %}
{% if passedInList.index %} do something {% endif %}
{% endwith %}
(Also, seems like you can use forloop.counter instead of forloop.counter0|add:"1")
It is able to write {{ myval.add:5 }}, {{ myval|add:value }} and even {{ myval|add:-5 }}.
However, I can't find out what I should type to add value * -1 like {{ myval|add:-value }}. This doesn't work, sadly.
You need to use double quotes:
{{ myval|add:"-5" }}
This subtracts five from myval.
The built-in Django template tags/filters aren't all-encompassing, but it's super easy to write your own custom template tags: https://docs.djangoproject.com/en/dev/howto/custom-template-tags/
You could make your own subtract template tag pretty easily:
#register.filter
def subtract(value, arg):
return value - arg
Use django-mathfilters from PyPI: https://pypi.python.org/pypi/django-mathfilters
To install :
$ pip install django-mathfilters
Then add mathfilters in your INSTALLED_APPS.
In template:
{% load mathfilters %}
<ul>
<li>8 + 3 = {{ 8|add:3 }}</li>
<li>13 - 17 = {{ 13|sub:17 }}</li>
{% with answer=42 %}
<li>42 * 0.5 = {{ answer|mul:0.5 }}</li>
{% endwith %}
{% with numerator=12 denominator=3 %}
<li>12 / 3 = {{ numerator|div:denominator }}</li>
{% endwith %}
<li>|-13| = {{ -13|abs }}</li>
</ul>
I recently started working with Django and stumbled upon this one as well: I needed a very simple template loop that stops printing after n times and shows a "more" link to toggle the rest of the items.
With great interest I read the struggle of people trying to understand why this is not being added to the Django default filters (since before 2013). I didn't feel like creating a custom template tag and I kind of found a way to subtract 2 variables using strings and add in combination with with and stringformat
Let's say I have a list of items where I want to print the first 2 and hide the rest, showing how many hidden items are there, eg.
John, Anna and 5 others like this (when given a list of 7 items)
As long as the number of visible items is harcoded in the template (eg. 2), it's possible to add the negative 2 |add:"-2", but I wanted the number of visible items to be a variable as well. The Math-filter library as suggested above doesn't seem up to date (I haven't tested it with Django 2.x).
The trick seems to be to use the add helper to concat the strings "-" with the integer as string, so it can be coerced back to a negative integer in a any consecutive calls to the add helper. This doesn't work however if the value is not a string, so that's where the stringformat helper comes in.
With string value
template posts.html (note how visible is explicitely passed as string - alternative below)
{% for post in posts %}
<h4>{{ post.title }}</h4>
...
{% include 'show_likes.html' with likes=post.likes visible="3" %}
{% endfor %}
template show_likes.html (note the add:0 to make the boolean operator work)
{% with show=visible|default:"2" %}
{% for like in likes %}
{% if forloop.counter <= show|add:0 %}
{% if not forloop.first %},{% endif %}
{{ like.username }}
{% endif %}
{% endfor %}
{% if likes|length > show|add:0 %}
{% with rest="-"|add:show %}
and {{ likes|length|add:rest }} more
{% endwith %}
{% endif %}
like this
{% endwith %}
Alternative with integer
You could just convert your integer to a string in the calling template using |stringformat:"d"
If however the number of visible items you want to show is an integer, you'll have to add a call to stringformat:"d" to have it converted to string
template posts.html
{% for post in posts %}
<h4>{{ post.title }}</h4>
...
{% include 'show_likes.html' with likes=post.likes visible=3 %}
{% endfor %}
template show_likes.html
{% with show=visible|default:2 %}
{% with show_str=show|stringformat:"d" %}
{% for like in likes %}
{% if forloop.counter <= show %}
{% if not forloop.first %},{% endif %}
{{ like.username }}
{% endif %}
{% endfor %}
{% if likes|length > show|add:0 %}
{% with rest="-"|add:show_str %}
and {{ likes|length|add:rest }} more
{% endwith %}
{% endif %}
{% endwith %}
{% endwith %}
Since I'm a very beginner with Django and Python, I'm pretty sure this approach is far worse than actually creating a custom helper! So I'm not suggesting anyone should be using this. This was just my attempt on trying to solve this with the available template helpers and without any custom stuff.
Hope this helps
Lo primero es multiplicar por -1 para convertirlo en una valor negativo y guardarlo en una variable y posterior a usar la suma
The first thing is to multiply by -1 to turn it into a negative value
and save it in a variable and then use the add
{% widthratio val2 1 -1 as result %}
{{result|add:val1}}
After search I found that I can make {% with var=value %} with filters to make the arithmetic operations "with other variables or not"
For example: I have x = 5 and y = 3 and need to add the y's value to x value, all what I need is these steps:
1- Create variable x : {% with x=5 %}
2- Create variable y : {% with y=3 %}
3- In my HTML tags, say <h1>, write that : <h1>{{ x|add:y }}</h1>
4- Close the y's with : {% endwith %}
5- Close the x's with : {% endwith %}
Hope it works with you, it worked with me.
{% with i=3 %}
{% with x=1 %}
<h1>{{i|add:x}}</h1> <!-- result is 4 -->
{% endwith %}
{% endwith %}
I want to create such loop:
{% for object in objects %}
{% if object.before != object %}
{{ object }} this is different
{% else %}
{{ object }} this is the same
{% endfor %}
Based on https://docs.djangoproject.com/en/dev/ref/templates/builtins/?from=olddocs#for I can't. Is there really no simple way to do this? Or I just need to use counter and check for objects[counter-1]?
P.S. .before is theoretical and objects is simple query list. I want to take and do something with the loop member that encountered before current loop member.
Check ifchanged template tag
There is a "simple way" to do this: write a custom template tag. They're really not hard. This would probably do the trick (untested):
#register.simple_tag
def compare_objects(object_list):
comparisons = []
for i in range(1, len(object_list)):
if object_list[i] > object_list[i-1]:
comparisons.append('bigger')
else:
comparisons.append('smaller')
return comparisons
The built-in template tags and filters don't make it easy (as of Django 1.4), but it is possible by using the with tag to cache variables and the add, slugify, and slice filters to generate a new list with only one member.
The following example creates a new list whose sole member is the previous member of the forloop:
{% for item in list %}
{% if not forloop.first %}
{% with forloop.counter0|add:"-1" as previous %}
{% with previous|slugify|add:":"|add:previous as subset %}
{% with list|slice:subset as sublist %}
<p>Current item: {{ item }}</p>
<p>Previous item: {{ sublist.0 }}</p>
{% endwith %}
{% endwith %}
{% endwith %}
{% endif %}
{% endfor %}
This isn't an elegant solution, but the django template system has two faults that make this hack unavoidable for those who don't what to write custom tags:
Django template syntax does not allow nested curly parenthesis. Otherwise, we could do this:
{{ list.{{ forloop.counter|add:-1 }} }}
The lookup operator does not accept values stored using with (and perhaps for good reason)
{% with forloop.counter|add:-1 as index %}
{{ list.index }}
{% endwith %}
This code should work just fine as a django template, as long as object has a property or no-argument method called before, and objects is iterable (and '<' is defined).
{% for object in objects %}
{% if object.before < object %}
this is bigger
{% else %}
this is smaller
{% endfor %}