Extend the {% for %} tag to work as a simple loop

[Chris Beaven]

It's come up several times in IRC that people wanted to be able to just do a simple loop (repeat this X times) in their template.

The attached patch extends the {% for %} tag so it can also work like this:

{% for 5 %}
repeat me
{% endfor %}

It also works with integer variables and the forloop variable is still available within the loop:

{% for my_integer %}
loop: {{ forloop.counter }}
{% endfor %}

[Chris Beaven]

Tests and docs included, just need a decision.

[Adrian Holovaty]

Hmm, this one merits some discussion. I like the general idea but need to mull over the syntax.

[Vincent Foley]

I added a patch of my own. It's more complex than SmileyChris' and needs documentation (and possibly more tests.) Let me know what you think of the general syntax. The patch is attached.

Example usage:

{% for i 1 to 5 %}
    {{ i }}
{% endfor %}

{% for i 1 to 5 by 2 exclusive %}
    {{ i }}
{% endfor %}

{% for i 5 to 1 by -2 %}
    {{ i }}
{% endfor %}

[anonymous]

Ugh, I don't like at all, sorry gnuvince. The aim isn't to make Django templates into python...

[durdinator]

Why a significant syntax change instead of a one-liner filter?

@register.filter
def times(count):
    return range(int(count))

{% for item in 5|times %}
  repeat me
{% endfor %}

[Chris Beaven]

Replying to durdinator:

Why a significant syntax change instead of a one-liner filter?

Because it looks simpler (and it's a syntax extension, really) and because then you're stuck with a pointless item context var.

Neither of which are convincing arguments. And talking about this at sprint, it seemed like the core would just prefer to have a new filter named something separate anyway so I don't hold much hope for my patch really :)

[Vincent Foley]

How about something like:

{% times 5 %}
    {{ times.iter0 }}
    {{ times.iter1 }}
    <br />
{% endtimes %}

# Output
0 1
1 2
2 3
3 4
4 5

[Vincent Foley]

P.S.: times is just a tentative name. I think repeat would be better.

[Chris Beaven]

And that's why I like it attached to {% for %} - then you get all of the forloop context variable goodness for free.

[Jacob]

I just can't come up with a use case that isn't something better done in a view or better done by just writing out the rows by hand. Besides, this is a pretty simple thing to add as a custom tag in your app.

[danielcristian]

I had this model:

class Mana(models.Model):
    name = models.CharField(u'Mana', max_length=200, unique=True)
    image = models.ImageField(u'Symbol', upload_to='manas/')

class Cost(models.Model):
    card = models.ForeignKey(Card)
    quantity = models.IntegerField('Quantity', max_length=2)
    mana = models.ForeignKey(Mana, related_name=u'mana', verbose_name=u'Mana')

(Yes, it's related to Magic Cards...)

Some cards had a cost with a quantity value (1 Forest, 3 Islands, 5 Mountains), and I need to loop quantity times to show n-times the image cost.

It could be done with this kind of loop.

[James Bennett]

Please do not reopen a ticket that's been marked "wontfix" by a core developer; if you strongly disagree, consider starting a discussion on the developers' mailing list.

[anonymous]

Replying to jacob:

I just can't come up with a use case that isn't something better done in a view or better done by just writing out the rows by hand. Besides, this is a pretty simple thing to add as a custom tag in your app.

This ticked is old, but to present you with a scenario that I'm into right now: I need to create a varying number of radiobuttons, depending of the number of choices allowed by the parents settings. The parent has a "number of objects allowed" field in the model. I therefore need to repeat a tag that can do the same thing {% for %}, but not iterating over an array or set, but just a variable number.