Develop Reference

How to count authors in Pelican Blogs?

I was trying to make my blog show "Authors" instead of "Author" when there are more than 1 authors for the same article.
The solution (thanks to #Avaris) is to set i = article.authors|count and that can be used as follows
<div align="right">
{% set i = article.authors|count %}
{% if i != 1 %}
Authors:<br>
{% endif %}
{% if i == 1 %}
Author:<br>
{% endif %}
{% if article.authors %}
{% for author in article.authors %}
{{ author }}<br>
{% endfor %}
{% endif %}
</div>
This is different to Set variable in jinja because in Pelican I cannot find a command like lenght(authors) to obtain a number to define a condition.

Declare variable and if statement in Django template

I am developing an application with python Django
what I need to do is to assign a class to a div based on the counter variable value in templates
{% with 1 as counters %}
{% for importance in all_importance %}
{% if counters == 1 %}
<div class="item active" >
{% else %}
<div class="item" >
{% endif %}
{% for image in importance.subtypemodelimage_set.all %}
<img src="{{ image.image.url }}" />
{% endfor %}
</div>
{% counters += 1 %}
{% endfor %}
{% endwith %}
But I face this issue
Invalid block tag: 'counters', expected 'empty' or 'endfor'
where am I making mistake, thanks in advance for your helps

The for loop sets a number of variables available within the loop (full list in django docs here):
...
forloop.first True if this is the first time through the loop
forloop.last True if this is the last time through the loop
...
you can use forloop.first to check for first loop iteration:
{% for importance in all_importance %}
{% if forloop.first %}
<div class="item active" >
{% else %}
<div class="item" >
{% endif %}
{% for image in importance.subtypemodelimage_set.all %}
<img src="{{ image.image.url }}" />
{% endfor %}
</div>
{% endfor %}

Problem is with
{% counters += 1 %}
There is not tag counters. You are interpreting variable as tag.
More over you can't implement that kind of for loop in django template.

Django {% blocktrans %}: How to handle pluralization inside a for loop?

I have the following loop in my Django template:
{% for item in state.list %}
<div> HTML (CUSTOMERS BY STATE) </div>
<!-- print sum of customers at bottom of list -->
{% if forloop.last %}
<h4>{{ forloop.counter }} Valued Customers</h4>
{% endif %}
{% endfor %}
Obviously, if I end up with only one customer, I'd like to print singular "Valued Customer"
According to Django's docs, one should use blocktrans. Tried the following, a few flavors of nesting:
{% blocktrans count %}
{% if forloop.last %}
<h4>
{{ forloop.counter }}
Valued Customer
{% plural %}
Valued Customers
</h4>
{% endif %}
{% endblocktrans %}
Keep getting TemplateSyntaxError: Invalid block tag: 'blocktrans', expected 'empty' or 'endfor'
Is there no way to combine with another loop? Any ideas how to solve? Thanks!

Here is the working code, thanks to alko:
{% load i18n %}
<!-- ... -->
{% if forloop.last %}
<h4>
{{ forloop.counter }}
{% blocktrans count count=forloop.counter %}
Valued Customer
{% plural %}
Valued Customers
{% endblocktrans %}
</h4>
{% endif %}

Probably, you forgot to load translation tags. Add following line at the top of your template:
{% load i18n %}
After you fix that, note that for a blocktrans tag after count a variable, whose value will serve for plural detection, should be specified, so you probably need something like
{% blocktrans count count=forloop.counter %}

To pluralize use this:
Customer{{ forloop.counter|pluralize }}

Does Jinja2 support nested if statements?

I read the docs and I am not clear on this is right at all. I know you can use nested for loops, but if statements seem to be different.
Can i do the following?
{% if thing=true %}
<div> something here</div>
{% if diffthing=true %}
<div> something else</div>
{% else %}
<div> third thing</div>
{% endif %}
{% else %}
<div> nothing here </div>
{% endif %}
Or should the format be different somehow?

Jinja2 supports nested blocks, including if statements and other control structures.
See the documentation on Block Nesting and Scope: "Blocks can be nested for more complex layouts."
A good use case for this is writing macros that conditionally output HTML:
{# A macro that generates a list of errors coming back from wtforms's validate function #}
{% macro form_error_summary(form, li_class='bg-danger') %}
{# only do the following on error... #}
{% if form.errors %}
<ul class="errors">
{# you can do layers of nesting as needed to render your content #}
{% for _field in form %}
{% if _field.errors %}
{% for error in _field.errors %}
<li class={{li_class}}>{{_field.label}}: {{ error|e }}</li>
{% endfor %}
{% endif %}
{% endfor %}
</ul>
{% endif %}
{% endmacro %}

The answer is yes.
I'm using logic very similar to yours in a live application and the nested if blocks work as expected. It can get a little confusing if you don't keep your code clean, but it works fine.

It seem possible. Refer to the documentation here: http://jinja.pocoo.org/docs/templates/#if

Just a quick add, if you're unpacking data to populate your fields, Jinja will only unpack it once. I had a similar problem with MongoDB and found if you change the item to a list item you iterate through it more than once without nesting
#app.route("/")
#app.route("/get_shrink")
def get_shrink():
# find and sort shrink top 5
shrink = list(mongo.db.shrinkDB.find().limit(5).sort(
"amount_lost_value", -1,))
return render_template(
"shrink.html", shrinkDB=shrink)
{% for shrink in shrinkDB %}
{% if shrink.resolved == true %}
<li>{{ shrink.product_name }} ||£ {{ shrink.amount_lost_value }} || {{ shrink.date }}</li>
{% endif %}
{% endfor %}
</span>
</div>
</div>
<div class="col s12 m5 offset-m2">
<h4>Top 5 Resolved Threats</h4>
<div class="card-panel light-blue">
<span class="white-text">
<!-- Shrink For loop top 5 resolves-->
{% for shrink in shrinkDB %}
{% if shrink.resolved != true %}
<li>{{ shrink.product_name }} ||£ {{shrink.amount_lost_value }} || {{ shrink.date }}</li>
{% endif %}
{% endfor %}

Django if statement not working

{% extends "base.html" %}
{% block content %}
<h1>{{ page }}</h1>
{% for category in categories %}
{% if category.page == page %}
<h2>{{ category.title }}!</h2>
{% for item in categoryitems %}
{{ category.title }} {{ item.category }}
{% if item.category == category.title %}
<h3>{{ item.title }}</h3>
{% endif %}
{% endfor %}
{% endif %}
{% endfor %}
{% endblock %}
The first statement if category.page == page is working fine, but the other one - if item.category == category.title - doesn't, for the sake of checking if everything is fine I've also added those {{category.title}} and {{item.category}} outputs and they are identical, so why doesn't the loop show me my item.title ? Without the if, it works, but, of course, shows every element in the list, which is smthn I don't need.

Do not depend on the page output to tell you what is correct, since the output is dependent on the code. Instead, do it correctly in the first place.
{% if item.category == category %}