Table.page handle incorrect page number

[andir]

Hi,
Are there any thoughts yet on changing the handling of invalid page numbers to provide a default behaviour (empty table/first page/HttpRedirect/..)?

In the django documentation (https://docs.djangoproject.com/en/dev/topics/pagination/?from=olddocs#using-paginator-in-a-view) is a reference implementatoin which handels the EmptyPage and PageNotAnInteger exceptions accordingly.

In my current straight forward use case (example code below) I'd have to catch the Http404 Exception raised by the Paginator during the render() call, call table.page() and handle the 2 exceptions accordingly which doesn't feel very good. I could also implement an own Paginator (derived from django.core.Paginator) which does the handling but still feels like a bit too much "work".

It would also be alot more uglier with multiple tables on the same page..

My proposal would be some sort of Meta options flag on how to handle invalid page numbers.

---

 table = Table(queryset)
 table.RequestConfig(request).configure(table)
 return render(request,'xyz.html',{'table':table}, context_instance=request_context)

[bradleyayers]

I hadn't thought about this before, but I totally agree. I think Table.page should be rewritten to not handle the exception, that code should be moved to SingleTableMixin. However as the code should be customisable.

I feel like perhaps pagination.page(number) should actually be executed in Table.paginate, so that EmptyPage and PageNotAnInteger are raised those that call, rather than being delayed until Table.page.

One possible pattern would be to just require get_table to be implemented in subclasses:

class Example(tables.Table):
    # ...

    def get_table(self):
        try:
            return super(Example, self).get_table()
        except PageNotAnInteger:
            # ...
        except EmptyPage:
            # ...

I'm not sure how the Meta flag you option would allow arbitrary handling of pagination exceptions (and really the general case here is table configuration errors)

[andir]

Yes, I agree moving pagination.page(n) to Table.paginate would actually work quiet well. The pattern you mentioned would be even better (one place to implement the handling vs. dozens of (nearly) equal code parts).

With the Meta flag I just thought about a way to switch between the current and possible new behavior for compatibility reasons. So the "new" behavior would be opt-in for a while. There might be people checking for the Http404-Exception atm.

[bradleyayers]

Any thoughts on the Meta variable name? Alternatively it could be passed to Table.paginate(), and set as a default in SimpleTableMixin.

[andir]

Something along the lines of "page_out_of_bounds_action"(=404/page1/...) ? But thats terribly long....
I'm also thinking about a way to do things like an HttpRedirect in that case.. so maybe re-raising should be also possible?

[bradleyayers]

RequestConfig now handles pagination errors silently. This happens when silent=True is included in its paginate argument, e.g. RequestConfig(..., paginate={"silent": True}) (or when it's not specified). It handles exceptions as follows:

• EmptyPage -> render last page
• PageNotAnInteger -> render first page