Determine empty template variable in Django

Question

I'm not able to determine whether a variable is empty when used in the template. I've iterated through the whole collection and in each I'm looking for a variable narrative_text.

I tested the empty variable by

{% ifnotequal narratives.narrative_text '' %}

I notice the control enters this block, but prints nothing/blank when the

{{  narratives.narrative_text }} 

is encountered.

So, how do I precisely check if the variable is empty?

I read the docs and found out that invalid/empty template variables are replaced by ''.

The doc says that

the template system inserts the value of the TEMPLATE_STRING_IF_INVALID setting.

Do we have to explicitly enter that into the settings.py? I tried doing so but still I haven't been able to make it work.

c=Context({ 
    "narratives_list":all_narratives,
    "patient_name":care_seeker_name
})

all_narratives is returned by a pymongo database call.

{%  for narratives in narratives_list  %}
<tr>
<td class = "date_col">
    7 Aug, 2012
</td>
{%  ifnotequal narratives.narrative_text '' %}
<td>
<div class = "narrative">
    ( text narrative )
<b> 
    {{ narratives.about }}
</b>
<br><br>
{{ narratives.narrative_text }}
</div>  
</td>   
{%  else %}
<td>
<div class="scans">
<div class="gallery">
<b> {{ narratives.about }}</b>
<br><br>
<a href="https://udhc1-nodejstest.rhcloud.com/my_image/{{ narratives.file_id }}">
<img src="https://udhc1-nodejstest.rhcloud.com/my_image/{{ narratives.file_id }}" width="72" height="72" alt="" />
</a>
</div>
</div>
</td>
{%  endifnotequal %}

Answer 1

Pipe through length and do your test against that value.

{% if narratives.narrative_text|length > 0 %}
    {{ narratives.narrative_text }}
{% else %}
    None
{% endif %}

Answer 2

Just confirmed via my own code using django 2.1.3 and python 3.5 and 3.7 that the following works:

{% if narratives.narrative_text %}
    # do something
    {{ narratives.narrative_text }}
{% else %}
    # do something else
    None  # displays "None" 
{% endif %}