Question

what does django do, when i do something like that in template

{{ object.parameter }}

I ask this because in case of arrayfields (postgresql array fields) it will print out either

{'value', 'value', 'value'}

(because thats how postgresql stores arrays in arrayfields)

or

['value','value','value']

if i use fields post_init method to convert postgresql array to python list.

Desired output would of course be value, value, value. I would rather not use some kind of filters for that, because then i would have to resort using IFs in templates or use some kind of template tag filter for every value i print out and that does not feel like a smart thing to do.

By the way, i know i can do something like that in template :

{% for choice in field.choices %}
    {{ choice }}
    {% if forloop.last %}
    {% else %}, 
    {% endif%}
{% endfor %}

and that gives me exactly what i want, but i thought there would be some other way doing it – with some modelfield method or something.

Alan

Answer 1

what does django do, when i do something like that in template

{{ object.parameter }}

See variables and lookups.

Desired output would of course be value, value, value. I would rather not use some kind of filters for that, because then i would have to resort using IFs in templates or use some kind of template tag filter for every value i print out and that does not feel like a smart thing to do.

You can make a really trivial filter:

@register.filter
def comma_join(values):
    return u', '.join(values)

So simple:

{{ object.parameter|comma_join }}

Why would you want to avoid such a simple solution ?

and that gives me exactly what i want, but i thought there would be some other way doing it – with some modelfield method or something.

Of course you could also add such a method:

class YourModel(models.Model):
    # ....
    def comma_join_parameter(self):
        return u', '.join(self.parameter)

And use it in your template as such:

{{ object.comma_join_parameter }}