How can I use a variable as index in django template?

Question

Right now I get this error:

Exception Type:
TemplateSyntaxError

Exception Value:    
Could not parse the remainder: '[year]' from 'bikesProfit.[year]'

I also tried {{ bikesProfit.year }} but this gives an empty result.

 {%  for year in years_list %}

        <tr>
            <th>Total profit {{ year }}:</th>
        </tr>
        <tr>
            <th></th>
            <th> {{ bikesProfit[year] }} </th>

...

If bikesProfit is an dict passed to the context with the format `{2012:10.0, 2011:13.0}` then `bikesProfit.year` should work. Are you perhaps mixing `str` and `int` keys for year? — RickyA, Nov 14 '12 at 10:16
Also usable: http://stackoverflow.com/questions/1700661/access-array-elements-in-a-django-template — RickyA, Nov 14 '12 at 10:17
What do `bikesProfit` and `years_list` look like when you pass them to the context? — RickyA, Nov 14 '12 at 10:22
Have you tried that RickyA? It seems to me that it shouldn't work since the key is not `year`, but the actual year (2000). — Martin Maillard, Nov 14 '12 at 10:23
Trying now and indeed not working. It does bikesProfit["year"]. Bah. — RickyA, Nov 14 '12 at 10:53

Serhii Holinei · Accepted Answer · 2014-04-28T09:09:37.443

22

It's a very common question, there are a lot of answers on SO.

You can make custom template filter:

@register.filter
def return_item(l, i):
    try:
        return l[i]
    except:
        return None

Usage:

{{ bikesProfit|return_item:year }}

edited Apr 28 '14 at 09:09

answered Nov 14 '12 at 10:12

Serhii Holinei

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@goliney as this is the first answer on google, you might consider placing the `:` behind the function header! Aaaand I`m out... – enpenax Apr 28 '14 at 02:06
@user2033511 thank you, on my way to editing the answer – Serhii Holinei Apr 28 '14 at 09:09

score 3 · Answer 2 · edited May 23 '17 at 12:16

I don't think this is directly possible (edit: you can manually implement it with filters, as shown in goliney's answer). The documentation says:

Because Django intentionally limits the amount of logic processing available in the template language, it is not possible to pass arguments to method calls accessed from within templates. Data should be calculated in views, then passed to templates for display.

If your case is not more complicated than what you're showing, the best solution in my opinion would be to loop over bikeProfit instead.

{% for year, profit in bikeProfit.items %}
    ...
    <th>Total profit {{ year }}:</th>
    ...
    <th> {{ profit }} </th>
    ...

score 2 · Answer 3 · answered Nov 14 '12 at 10:25

It's possible, but goes against the grain of the Django model...

If you have items of interest, then ideally your view should return an object just containing those items, (OTTOMH something like):

Something.objects.filter(something__typename='Bike', year__range=(1998, 2001))

How can I use a variable as index in django template?

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