Develop Reference

How can I print a list with jinja2?

I'm trying to generate an HTML table with Jinja2. The data for the table is in an collections.OrderedDict where the keys are strings and the values are lists of strings.
I've tried to implement it using the following loops:
{% for key in table.keys() %}
{% for a_list in table[key] %}
{% for a_value in a_list %}
{{ a_value }}
{% endfor %}
{% endfor %}
{% endfor %}
Except in the Python console this works but in Jinja2 it dies with the error TypeError: 'int' object is not iterable
How do I iterate through a list in Jinja2?

You have one loop too many. table[key] is a list object, so looping over that gives you the values in the list:
{% for key in table.keys() %}
{% for a_value in table[key] %}
{{ a_value }}
{% endfor %}
{% endfor %}
Your extraneous loop tried to loop over the integer objects in your lists. Note that you don't need to loop over the keys() result; you can loop directly over the dictionary:
{% for key in table %}
{% for a_value in table[key] %}
{{ a_value }}
{% endfor %}
{% endfor %}
If you are not using the key in the loop, just loop directly over the values:
{% for list_value in table.values() %}
{% for a_value in list_value %}
{{ a_value }}
{% endfor %}
{% endfor %}

How to get the current index of for loop with jijna2?

Let's say that I have a code like:
{% for x in posts %}
<p>We are in item: {{ x }}</>
{% else %}
And I want to get the current index of the for loop to run an if loop, something like(logically):
{% for x in posts %}
{% if x.index = 0 %}
<p>We are in the first item!</p>
{% else %}
<p>We are in item: {{ x }}</>
{% endif %}
{% endfor %}
How to do it inside jijna2? (I use Python with Flask).

You can use loop.index inside the loop.
{% for x in posts %}
<p>We are in item number: {{ loop.index }}</>
{% else %}
Flask Template docs

You can use several loop related variables for that
http://jinja.pocoo.org/docs/dev/templates/#list-of-control-structures

Jinja: loop to create form fields with same name but the last character

I am using Flask and I have a WTF form with 12 input fields named like sold_1, sold_2,..., sold_12.
I would like to generate these fields in Jinja using a loop like:
{% for r in range(1, 13) %}
{{ form.sold_ }}{{ r }}
{% endfor %}
or a similar syntax, but it doesn't work.
I solved it in a quite convoluted way as follows:
{% set tmp = "sold_x" %}
{% for r in range(1, 13) %}
{{ form[tmp | replace('x', r)] }}
{% endfor %}
but I wonder whether there is a cleaner way.
Thanks

You could use this:
{% for r in range(1, 13) %}
{{ form.sold_ ~ r }}
{% endfor %}
or, if you want your input fields names to be sold_nr:
{% for r in range(1, 13) %}
{{ 'sold_' ~ r }}
{% endfor %}
See this answer for more detail.
EDIT
Using the #dirn and #Libra sugestions the correct answer is:
{% for r in range(1, 13) %}
{{ form['sold_' ~ r] }}
{% endfor %}

django template - for loop over 2 querysets

I am getting 2 querysets from db:
all_locations = Locations.objects.all()[:5]
rating = Rating.objects.all()[:5]
return render_to_response('index.html',{'all':all_locations,'rating':rating},context_instance=RequestContext(request))
But I am stuck here, not knowing how to loop over these 2 querysets in one loop. this is being wrong:
{% if all and rating %}
{% for every in all and rating %}
{{every.locationname}}, {{every.rating_score}}
{% endfor %}
{% endif %}

You can try zip(all_locations, rating). It will produce a list of tuples. Then you can iterate over them in pairs. Here is an example: (demo)
all_locations = ['ca','ny','fl']
ratings = ['best','great','good']
for (l,r) in zip(all_locations,ratings):
print l+':'+r
Outputs
ca:best
ny:great
fl:good

I have also come across this problem. Now I've fixed it.
what I do is using
new=tuple(zip(queryset1,queryset2))
return render(request, 'template.html', {"n": new}).
in view.py.
In template.html, I use three for sentences which are list below.
{% for i in n %}
{% for j in i|slice:"0:1" %}
......operate queryset1
{% endfor %}
{% for z in i|slice:"1:2" %}
.....operate queryset2
{% endfor %}
{% endfor %}
It seems this method will fulfill your needs.

this might work:
{% with rating|length as range %}
{% for _ in range %}
{{ rating[forloop.counter] }}
{{ location[forloop.counter] }}
{% endfor %}
{% endwith %}
i'm not sure if rating|length will to the job... you might need to add rating|length|times' withtimes` filter defined as:
#register.filter(name='times')
def times(number):
return range(number)

How to increment a variable on a for loop in jinja template?

I would like to do something like:
variable p is from test.py which is a list ['a','b','c','d']
{% for i in p %}
{{variable++}}
{{variable}}
result output is:
1 2 3 4

You could use loop.index:
{% for i in p %}
{{ loop.index }}
{% endfor %}
Check the template designer documentation.
In more recent versions, due to scoping rules, the following would not work:
{% set count = 1 %}
{% for i in p %}
{{ count }}
{% set count = count + 1 %}
{% endfor %}

After 2.10, to solve the scope problem, you can do something like this:
{% set count = namespace(value=0) %}
{% for i in p %}
{{ count.value }}
{% set count.value = count.value + 1 %}
{% endfor %}

As Jeroen says there are scoping issues: if you set 'count' outside the loop, you can't modify it inside the loop.
You can defeat this behavior by using an object rather than a scalar for 'count':
{% set count = [1] %}
You can now manipulate count inside a forloop or even an %include%. Here's how I increment count (yes, it's kludgy but oh well):
{% if count.append(count.pop() + 1) %}{% endif %} {# increment count by 1 #}
Or...
{% set count = [] %}
{% for something-that-loops %}
{% set __ = count.append(1) %}
<div> Lorem ipsum meepzip dolor...
{{ count|length }}
</div>
{% endfor %}
(From comments by #eyettea and #PYB)

Here's my solution:
Put all the counters in a dictionary:
{% set counter = {
'counter1': 0,
'counter2': 0,
'etc': 0,
} %}
Define a macro to increment them easily:
{% macro increment(dct, key, inc=1)%}
{% if dct.update({key: dct[key] + inc}) %} {% endif %}
{% endmacro %}
Now, whenever you want to increment the 'counter1' counter, just do:
{{ increment(counter, 'counter1') }}

if anyone want to add a value inside loop then you can use this its working 100%
{% set ftotal= {'total': 0} %}
{%- for pe in payment_entry -%}
{% if ftotal.update({'total': ftotal.total + 5}) %}{% endif %}
{%- endfor -%}
{{ftotal.total}}
output = 5

Came searching for Django's way of doing this and found this post. Maybe someone else need the django solution who come here.
{% for item in item_list %}
{{ forloop.counter }} {# starting index 1 #}
{{ forloop.counter0 }} {# starting index 0 #}
{# do your stuff #}
{% endfor %}
Read more here:
https://docs.djangoproject.com/en/1.11/ref/templates/builtins/

I was struggle with this behavior too. I wanted to change div class in jinja based on counter. I was surprised that pythonic way did not work. Following code was reseting my counter on each iteration, so I had only red class.
{% if sloupec3: %}
{% set counter = 1 %}
{% for row in sloupec3: %}
{% if counter == 3 %}
{% set counter = 1 %}
{% endif %}
{% if counter == 1: %}
<div class="red"> some red div </div>
{% endif %}
{% if counter == 2: %}
<div class="gray"> some gray div </div>
{% endif %}
{% set counter = counter + 1 %}
{% endfor %}
{% endif %}
I used loop.index like this and it works:
{% if sloupec3: %}
{% for row in sloupec3: %}
{% if loop.index % 2 == 1: %}
<div class="red"> some red div </div>
{% endif %}
{% if loop.index % 2 == 0: %}
<div class="gray"> some gray div </div>
{% endif %}
{% endfor %}
{% endif %}

Just to shed more light into this problem.
Jinja2 variables behaves differently from that of conventional scripting languages, you can't modify the variable in a for loop.Hence to bypass this behaviour you can use a dictionary, since you can change the value of the dictionary.
**{% set margin={"margin_value":0} %}**
{% for lang in language %}
<ul>
<li style="margin-right: {{ margin.margin_value}}px">{{ lang }}</li>
</ul>
**{% if margin.update({"margin_value":margin.margin_value + 2}) %}
{% endif %}**
{% endfor %}
In the above code the value of the dictionary is being modified.