Need to convert a string to int in a django template

Question

I am trying to pass in url parameters to a django template like this...

response = render_to_string('persistConTemplate.html', request.GET)

This the calling line from my views.py file. persistConTemplate.html is the name of my template and request.GET is the dictionary that contains the url parameters.

In the template I try to use one of the parameters like this...

{% for item in (numItems) %}

  item {{item}}

{% endfor %}

numItems is one of the url parameters that I am sending in my request like this...

http:/someDomain/persistentConTest.html/?numItems=12

When I try the for loop above, I get an output like this....

image 1 image 2

I am expecting and would like to see the word image printed 12 times...

image 1 image 2 image 3 image 4 image 5 image 6 image 7 image 8 image 9 image 10 image 11 image 12

Can anyone please tell me what I am going wrong?

Answer 1

you can coerce a str to an int using the add filter

{% for item in numItems|add:"0" %}

https://docs.djangoproject.com/en/dev/ref/templates/builtins/#add

to coerce int to str just use slugify

{{ some_int|slugify }}

EDIT: that said, I agree with the others that normally you should do this in the view - use these tricks only when the alternatives are much worse.

Answer 2

I like making a custom filter:

# templatetags/tag_library.py

from django import template

register = template.Library()

@register.filter()
def to_int(value):
    return int(value)

Usage:

{% load tag_library %}
{{ value|to_int }}

It is for cases where this cannot be easily done in view.

Answer 3

Yes, the place for this is in the view.

I feel like the above example won't work -- you can't iterate over an integer.

numItems = request.GET.get('numItems')

if numItems:
   numItems = range(1, int(numItems)+1)

return direct_to_template(request, "mytemplate.html", {'numItems': numItems})


{% for item in numItems %}
 {{ item }}
{% endfor %}

Answer 4

The easiest way to do this is using inbuilt floatformat filter.

For Integer

{{ value|floatformat:"0" }}

For float value with 2 precision

{{ value|floatformat:"2" }}

It will also round to nearest value. for more details, you can check https://docs.djangoproject.com/en/1.10/ref/templates/builtins/#floatformat.

Answer 5

You should add some code to your view to unpack the GET params and convert them to the values you want. Even if numItems were an integer, the syntax you're showing wouldn't give you the output you want.

Try this:

ctx = dict(request.GET)
ctx['numItems'] = int(ctx['numItems'])
response = render_to_string('persistConTemplate.html', ctx)

Answer 6

In my case one of the items was a string and you can not compare a string to an integer so I had to coerce the string into an integer see below

{% if questions.correct_answer|add:"0" == answers.id %}
    <span>Correct</span>
{% endif %}

Answer 7

You can do like that: if "select" tag used.

{% if i.0|stringformat:'s' == request.GET.status %} selected {% endif %}

Answer 8

My solution is kind of a hack and very specific..

In the template I want to compare a percentage with 0.9, and it never reaches 1, but all the values are considered string in the template, and no way to convert string to float.

So I did this:

{% if "0.9" in value %}
...
{% else %}
...
{% endif %}

If I want to detect some value is beyond 0.8, I must do:

{% if ("0.9" in value) or ("0.8" in value) %}
...
{% else %}
...
{% endif %}

This is a hack, but suffice in my case. I hope it could help others.