Question

I’m trying to display an HTML table of values with about 20 columns where say staff users see one subset of columns, and non-staff users see another subset of columns. I may want to define further types of users later. Now right now I have three static header rows so the template looks like

<table>
<tr>
  <th>Col A</th>
  {% if user.is_staff %}<th>Col B</th>{% endif %}
  ...
  {% if not user.is_staff %}<th>Col K</th>{% endif %}
</tr>
<tr>
  <td>Col A second header</td>
  {% if user.is_staff %}<td>Col B second header</td>{% endif %}
  ...
  {% if not user.is_staff %}<td>Col K second header</td>{% endif %}</tr>
<tr><td>Col A third header</td>  ...  </tr>

{% for obj in object_list %}
<tr>
  <td>{{ obj.col_a }}</td>
  {% if user.is_staff %}<td>{{ obj.col_b }}</td>{% endif %}
  ...
  {% if not user.is_staff %}<td>{{ obj.col_k }}</td>{% endif %}
</tr>
{% endfor %}</table>

However, I find non-DRY as every time, if I want to change if a user-type can see a column, I have to change it in 4 places. Or if I want to define multiple different classes of users, I’d have to have complicated if statements. I’d prefer something like

 {% if show_col_a %}<td>{{obj.col_a }}</td>{{% endif %}

Where I can define at the top of the template (or possibly in the view) that user.is_staff can see show_col_a. Is something like this possible? I’m using a generic view (object_list). Maybe modify all users to have attributes user.show_col_a somehow and do {% if user.show_col_a %}? I’m not sure how to add boolean attributes to users.

EDIT: May want multiple users with custom views (e.g., staff_view; admin_view, unprivileged, etc.), so if statements would get unwieldy. A cell’s contents is typically more complicated than {{ obj.col_b }}; tried simplifying problem to get to the point. E.g.:

<td>{% if obj.custom_address %}
  {{ obj.custom_address.webprint|safe }}
{% else %}
  {{ obj.business.address.webprint|safe }}
{% endif %}</td>

Also while multiple templates would work with a simple switch like:

{% if user.is_staff %}
   {% include "template_staff.html" %}
{% else %}{% if user.is_admin %}
   {% include "template_admin.html" %}
{% else %}
   {% include "template_other.html" %}
{% endif %}
{% endif %}

I find its not DRY at all; e.g., every edit to a template has to be replicated in three template. I guess I could make a script that read generates the three templates from some super_template outside of django but its getting very inelegant.

Answer 1

This depends a lot on what view you have and templates.

Ways to do:

• make a public template and staff template and add a simple method to change the templates on the fly for the views.

• make a template tag:

  {% is_staff myvar %}

tag code:

class IsStaffNode(Node):
    def __init__(self, var):
        self.var = var

    def render(self, context):
        if context['user'].is_staff():
            return var.resolve(context)
        return ""


@register.tag
def is_staff(parser, token):
    var = parser.compile_filter(token.split_contents()[1])
    return IsStaffNode(var)

Homework: make it a block tag to include the td’s so that it’s shown either all or none.

{% isstaff myvar %}<td>{{ myvar }}</td>{% endisstaff %}

This way is more labor intensive than 2 different templates, but if you want to try, manipulating the context (or creating a separate context for the block only) might be useful.

• Make a context processor that would fill the context with some variables if the user is staff, or not if not.
• Make a tag that would include the template (inherit from IncludeNode) and manipulate the context.