[5.2] Support composite column names like 'table.id' in chunkById

[mzur]

Example use case that didn't work before:

// both the annotations and images tables have an id column
DB::table('annotations')
   ->join('images', 'annotations.image_id', '=', 'images.id')
   ->where(/* something with images */)
   ->chunkById(500, $handleChunk, 'annotations.id');

As a workaround I used an alias for the ambiguous column:

DB::table('annotations')
   ->join('images', 'annotations.image_id', '=', 'images.id')
   ->where(/* something with images */)
   ->select('annotations.id as annotations_id', /* ... */)
   ->chunkById(500, $handleChunk, 'annotations_id');

But PostgreSQL for example doesn't allow the use of an alias in a where statement like it is built by chunkById.

[taylorotwell]

I worry this will create very unexpected behavior. For example if you select two columns with the same name and the last one specified is the one taken, then use this chunk method in this way to access the other tables ID, you will ACTUALLY be getting an entirely different table's ID, which would be very unexpected. I actually think it it is best to be specific about what you want using an alias in select then trying to be all fancy and actually open the door for unexpected behavior.

[GrahamCampbell]

Wouldn't PHP throw a warning about not providing a reference here?

[mzur]

Interesting point, one would certainly expect so. Apparently being wrapped in the helper function prevents the warning since this creates a new variable.

[mzur]

@taylorotwell Yes, you have a point. But it's not just trying to be fancy here, since my first example currently does not work (although one might expect it to) and my "workaround" with the alias only works with SQLite (as far as I know). Standard SQL doesn't allow a column alias in a where statement (e.g. Postgres, MySQL) but SQLite supports this in a non-standard way. The where statement is added by forPageAfterId.

What do you think of adding an optional fourth parameter to chunkById where the column alias can be defined? The alias will then be used instead of the $columnSuffix proposed by this PR which should not lead to unexpected behavior. Example:

DB::table('annotations')
   ->join('images', 'annotations.image_id', '=', 'images.id')
   ->where(/* something with images */)
   ->select('annotations.id as annotations_id', /* ... */)
   ->chunkById(500, $handleChunk, 'annotations.id', 'annotations_id');