django if condition not working when using variable, but when using number it's working

Question

why this code not working, i get variable "data" from views.py

when i change data.numrooms with number like '1', it's working well, but is use data.numrooms that's not working

<select class="form-control" name="numadults">
      <option value=''>No. of Adult</option>
          {% for i in range %}
             {% if data.numadults == i %}
                <option value="{{ i }}" selected>{{ i }}</option>
             {% else %}
                <option value="{{ i }}">{{ i }}</option>
             {% endif %}
          {% endfor %}
</select>

Where do You use data.numrooms? I see only data.numadults. — Fejs
– Fejs, Commented Apr 10, 2019 at 10:52

ruddra · Accepted Answer · 2019-04-10 11:07:49Z

1

Why not put that logic in the view and pass it to template like this:

# view

adult_range = list(map(lambda x: (x, True) if x == data.numadults else (x, False), range(1,10))

# Template
  <option value=''>No. of Adult</option>
      {% for i, selected in adult_range %}
         {% if selected %}
            <option value="{{ i }}" selected>{{ i }}</option>
         {% else %}
            <option value="{{ i }}">{{ i }}</option>
         {% endif %}
      {% endfor %}

edited Apr 10, 2019 at 11:07

answered Apr 10, 2019 at 10:57

ruddra

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Comments

subpleiades · Accepted Answer · 2019-04-10 14:41:37Z

Similarly to ruddra's solution, the easiest way to achieve this is probably to do the bulk of the logic in the view:

adults = [(element, element.number == data.numadults) for element in adult_list]

This will give you a list of two-tuples of (<adult object>, <boolean>) where the boolean represents the conditional you're trying to use in the template to decide whether to use selected attribute.

In the template, you can then base your conditional solely on that boolean:

<option value=''>No. of Adult</option>
{% for i, selected in adult_range %}
    {% if selected %}
        <option value="{{ i }}" selected>{{ i }}</option>
    {% else %}
        <option value="{{ i }}">{{ i }}</option>
    {% endif %}
{% endfor %}

Note though that you can also evaluate the condition inline, in the html tag, like so:

<option value="{{ i }}" {% if selected %} selected {% endif %}>

This might make for more readable code.

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