refactor collapse_wheres method so that string based where clauses are h...

[jorgevaldivia]

...andled

Fixes #361

[valscion]

👍 Is there anything that I can do to get this merged? We stumbled upon the same issue

[vellotis]

👍 Actually it started to bother me as well. Would be great if it could get merged.

[jlhonora]

@jorgevaldivia are you using this in prod? Any problems so far? Thanks for the PR btw.

[mckinnsb]

Is there anything that we are waiting for with this? @bigxiang

[kbaum]

I am using rails 4.2 and I noticed that just commenting out the collapse_where method solves the issue for me. I also noticed that only a few squeel tests fail when I comment out collapse_where and they seem like they may even be false alarms. See my comments here:

#416 (comment)

Full disclosure, I am not completely sure why collapse_where was added to begin with so i may be way off base.

Also, if we want to include a spec that reproduces the issue, I added one here:

https://github.com/viewthespace/squeel/commit/5571d4a96eb9d52f9427172acff6685b1692873f

thx!