Opened 16 years ago
Last modified 6 years ago
#9173 new New feature
Conditional content of template blocks
Reported by: | while0pass | Owned by: | nobody |
---|---|---|---|
Component: | Template system | Version: | dev |
Severity: | Normal | Keywords: | |
Cc: | masterjakul@…, FunkyBob | Triage Stage: | Someday/Maybe |
Has patch: | yes | Needs documentation: | no |
Needs tests: | no | Patch needs improvement: | yes |
Easy pickings: | no | UI/UX: | no |
Description
It will be very good if there is some possibility to mark sort of "conditional content" of the template blocks ({% block .. %}), that is the content that is displayed only if in a child template the block has some content. For instance, we have 2 templates:
parent.html <table> <tr> <td>{% block firstcol %}{% endblock %}</td> <td>{% block secondcol %}{% endblock %}</td> {% block thirdcol %}<td>{% blockcontent %}</td>{% endblock %} </tr> </table>
child.html {% extends 'parent.html' %} {% block firstcol %} 1 {% endblock %} {% block firstcol %} 2 {% endblock %}
We should have such an output text:
<table> <tr> <td> 1 </td> <td> 2 </td> </tr> </table>
but not the following:
<table> <tr> <td> 1 </td> <td> 2 </td> <td></td> </tr> </table>
Attachments (1)
Change History (11)
comment:1 by , 16 years ago
comment:2 by , 16 years ago
Triage Stage: | Unreviewed → Design decision needed |
---|
comment:3 by , 14 years ago
Severity: | → Normal |
---|---|
Type: | → New feature |
comment:4 by , 14 years ago
Easy pickings: | unset |
---|---|
Has patch: | set |
Version: | 1.0 → SVN |
This scratches an itch for me too, so I thought I’d implement it.
My patch in ticket9173.diff
(against r16253) implements a new tag, ifnotempty, with the following behaviour:
Renders only if at least one variable or template tag within also renders. This allows a variable or template tag to be surrounded by markup, with the markup omitted if the variable or template tag does not render. An `{% else %}` block may also be used. In the following example, the section will not be rendered unless another template extends this one and overrides the `more_information` block:: {% ifnotempty %} <section> <h1>More information</h1> {% block more_information %}{% endblock %} </section> {% endifnotempty %}
comment:6 by , 13 years ago
Cc: | added |
---|
comment:7 by , 12 years ago
Triage Stage: | Design decision needed → Someday/Maybe |
---|
I'm wholly unconvinced by the syntax proposed so far; it seems quite complicated and non-intuitive. However, I'm not opposed to the idea in general. So marking "someday" -- if someone comes up with syntax that makes sense and is easy to explain, then we might consider this.
comment:8 by , 11 years ago
Cc: | added |
---|
I ended up implementing a {% wrapif %} tag, which will render the [optional] head and tail blocks if the body renders as a non-blank [not all whitespace] string.
{% wrapif %} <td> {% body %} {% block whatever %}{% endblock %} {% tail %} </td> {% endwrapif %}
If body is omitted, the first block is assumed to be the body, and the head empty.
If tail is omitted, it is considered empty.
I mostly did this to help move container tags out of for loops, where they'd be inside a {% if forloop.first %} and thus cause a test every iteration.
comment:9 by , 10 years ago
I was thinking about this the other day. How about something like:
parent.html <table> <tr> <td>{% block firstcol %}{% endblock %}</td> <td>{% block secondcol %}{% endblock %}</td> {% block thirdcol if block.child %}<td>{{ block.child }}</td>{% endblock %} </tr> </table>
Which would introduce a {{ block.child }}
thing similar to {{ block.super }}
And also conditional blocks in general, in which you can specify:
{% block title if post.title %}My title{% endif%}
Which is the equivalent of, but shorter than:
{% block title %} {% if post.title %} {{ post.title }} {% else %} {{ block.super }} {% endif %} {% endblock %}
What do you think of all the above?
comment:10 by , 6 years ago
Patch needs improvement: | set |
---|
typo: second "firstcol" should be "secondcol", like this: