Custom tag to set a variable in Django template. Emptying the value out of context?

Question

In my Django Template I want to set a variable, to use in a html tag. But, when I'm out the for loop, the variable is empty :(

{% load custom_template_tag %}

<select>
    <option value=""></option>
    {% for a_status in status %}
        {% for r in all_status_ressources %}
            {% if a_ressource.id == r.0 and a_status.name == r.1 %}
                {% setvar "selected" as selected_status %}
                id ressource : {{ r.0 }}, name status : {{ r.1 }} -> [{{ selected_status }}]<br>
            {% endif %}
                selected_status : "{{ selected_status }}"
        {% endfor %}
        end loop ---------> selected_status : "{{ selected_status }}"
        <option value="{{ a_status.id }}" selected="{{ selected_status }}">{{ a_status.name }}</option>
    {% endfor %}
</select>

The custom tag itself :

from django import template

register = template.Library()


@register.simple_tag
def setvar(val=None):
    return val

And, now the debug trace :

selected_status : ""

id ressource : 2, name status : "my personnal status" -> [selected]

selected_status : "selected"
selected_status : "selected"
selected_status : "selected"
selected_status : "selected"
selected_status : "selected"
selected_status : "selected"
selected_status : "selected"
selected_status : "selected"
selected_status : "selected"
selected_status : "selected"
selected_status : "selected"
selected_status : "selected"
selected_status : "selected"
selected_status : "selected"

end loop ---------> selected_status : ""

So, when I'm out of the for loop, the varible is not set to be used in the html tag.

Why are you writing your own tag to do this, why not use `{% with = %}`? — Daniel, Sep 22 '21 at 13:44
How can I do with "with" ?. It's in a block, and in my code, there's aleardy blocks like "loop", "if", etc. — fabrice, Sep 22 '21 at 14:30
You face this problem because you don't pass data in a proper format to your template from your view. Your view should provide your data in such a manner that the template can render it easily. — Abdul Aziz Barkat, Sep 22 '21 at 14:46

Daniel · Answer 1 · 2021-09-23T13:13:31.377

0

You can use the built in {% with <var>=<val> %} tag:

Something like:

template.html

<select>
  <option value=""></option>
  {% for a_status in status %}
    {% for r in all_status_ressources %}
      {% if a_ressource.id == r.0 and a_status.name == r.1 %}
        {% with selected_status="selected" %}
          id ressource : {{ r.0 }}, name status : {{ r.1 }} -> [{{selected_status }}]<br>
        {% endwith %}
      {% endif %}
      selected_status : "{{ selected_status }}"
    {% endfor %}
    end loop ---------> selected_status : "{{ selected_status }}"
    <option value="{{ a_status.id }}" selected="{{ selected_status }}">{{a_status.name }}</option>
  {% endfor %}
</select>

edited Sep 23 '21 at 13:13

answered Sep 22 '21 at 14:40

Daniel

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So, after the {% endwith %} tag, the variable is not set. In my example, I can't retreive the value :( – fabrice Sep 23 '21 at 07:24
But, for now, in my first message, I don't understand why the value, after the loop, is empty. Any idea please ?. Thanks – fabrice Sep 23 '21 at 07:25
This is likely not a coding error but a logic error. What should the value of `selected_status` be outside of the if statement? – Daniel Sep 23 '21 at 13:15

Custom tag to set a variable in Django template. Emptying the value out of context?

1 Answers1