Issue/10 - Adds support to fetch all fields in get_results.

[alexstandiford]

Fixes #10

This makes it possible to pass an asterisk in the $cols argument, and fetch all fields for the current table.

This isn't a true 1:1 representation of SELECT *, instead, there's a tiny bit of logic that tells get_results to transform * into the column names via get_column_names(). I believe this will ensure compatibility with other facets of this class.

[szepeviktor]

@alexstandiford If you add Fixes #10 to the top comment GitHub will close that issue automatically on merge.

[JJJ]

I've spent a few days on & off thinking about this, and have concluded that there is something I do not love about it to merge it outright.

I do think the * makes sense, especially given what BerlinDB is and does.

I do not like that it's a hardcoded string used as a shortcut to mean "all columns."

It makes me think we should legitimize the idea of "all columns" further, throughout the project, rather than insert a single unique intercept point via a symbol that is widely understood – but not universally understood – to mean "everything".

'all_columns' => true or something, seems better, but I don't love that either.

Thoughts?

[alexstandiford]

@JJJ Seems like a good thought to me. I'll ponder a little more.

[JJJ]

Just dropping a note that I've been looking into this again. 👀

My opinion about * specifically has not changed, but I don't like my all_columns idea either. 🤪

I'd like to benchmark how * performs against actually including all columns in the query. 📈

Perhaps empty columns should just default to all columns instead? I'm not sure if that's counterintuitive or not, but it also seems unlikely anyone would intentionally call get_results() and expect it to return no results simply because columns were omitted, given that the calling class is fully aware of all of the columns in the Table/Query.

[alexstandiford]

I think this makes a lot of sense. It is consistent with what generally happens with the Query constructor. I think the consistency would be nice.

[JJJ]

Since get_results() calls $this->query(), I think a refreshed PR will need to change parse_fields() instead, and get_item_ids() inside of get_items() would end up being get_item_fields(), which ends up with a naming conflict, so will need to keep noodling on this still...