Moved table instantiation from get_context_data to get_tables

[sdolemelipone]

Further to the recent changes to MultiTableMixin by @vCra in issue #538, I would like to suggest the following change: get_tables should create table instances by calling get_tables_data, in an analogous manner to SingleTableMixin, rather than leaving it to get_context_data.

The use case for this is that sometimes it is necessary for table classes to be defined after get_tables_data is called, due to variable columns in the data. In those cases it is preferable to override get_tables to deal with the class instantiation. In the current implementation it is also necessary to override get_context_data in this situation, as that function has a preference on how table classes and their data are instantiated. IMO get_context_data should be concerned with adding the tables to the context, and agnostic about the table construction.

I have attached a PR showing the suggested changes.

[sdolemelipone]

Apologies for all the noisy commits, I got tox working now. :-)

[jieter]

Makes sense, thanks for the pull. I'll squash the commits to remove the noise ;)

[sdolemelipone]

Thanks! My first accepted PR :-)

[jieter]

👍 well done!

[jieter]

released 1.21.2