Question

I am using a Django Paginator and I want to have multiple available get parameters, such as:
page=1
sort_by=price

However, in my template tags I have:

Showing items sorted by {{ SORT_PARAM }}.
Showing {{ ITEMS_PER_PAGE }} items per page.

{% if has_prev %}
<a href="?page={{ prev_page }}">Previous</a> |
{% endif %}

However, this does not preserve the other GET variables. What I mean is, if I’m viewing

page/?page=1&sort_by=price

and I click the link in the template fragment above, I will go to

page=2

instead of

page=2&sort_by=price

What I mean is, the a href does not preserve the other GET parameters.

One solution is I could type all the possible GET parameters in the a href, such as

<a href="?page={{ prev_page }}&items_per_page={{ ITEMS_PER_PAGE }}&sort_param={{ SORT_PARAM }}">Previous</a>

but this will become less scalable the more arguments I want to add to my browsing. I’m guessing there should be an automated way to obtain all GET parameters, and then pass those and one more?

Answer 1

You can create a ‘parameter-string’. Let’s supose that in your code you have:

my_view( request, page, options):
    sort_choices = {P:'price',N:'name', ...}
    n_item_choices = {'S':5, 'L':50, 'XL':100)
    ascending_descending_choices = {'A':'', 'D':'-'}
    ...

then you can concatenat options as:

options='P-S-D'  #order by price, 5 items per page, descending order

encode opions as:

<a href="?page={{ prev_page }}&options={{ options }}">Previous</a>

then, in urls.py capture options and in view:

my_view( request, page, options):
   ... #choides ....
   try:
      optionsArray = options.split('-')
      sort_by = sort_choices[ optionsArray[0]  ]
      n_ites_page = n_item_choices[ optionsArray[1]  ]
      asc_or_desc = ascending_descending_choices[ optionsArray[2]  ]
      ...
   except:
      somebody is playing ....

with this method you are free to add more paginations options without modify urls.py, all you need is to append options at the end of string options . This has advantages but also some dangers: I hope you can identify risks.