Added toParam() for use with e.g. node-postgres' parameterized queries

[mtsr]

I've done some initial work on adding a toParam() function that produces a { text: '', values: [] } object for use with for example node-postgres' parameterized queries.

I've included tests for my changes, although I'm not familiar enough with the project to ensure complete coverage. I also changed the WhereBlock tests slightly because neither parameterized where's nor IN was being tested.

Documentation still needs to be done, but I didn't feel that was useful before discussing the functionality itself.

I still have to actually test this with node-postgres, but I'd love some feedback on this, that's why the pull-request already.

I haven't programmed CoffeeScript before, so there might be some javascript-isms in there, please feel free to point those out as well.

[mtsr]

What this pull request allows you to do is instead of

var query = squel.update()
  .table("students")
  .set("name", "$1")
  .set("gender", "$2")
  .toString();
// 'UPDATE students SET name = $1, gender = $2

// node-postgres client
client.query({ text: query, values: ['Thomas', 'M'] });

you can do

var query = squel.update()
  .table("students")
  .set("name", "Thomas")
  .set("gender", "M")
  .toParam();
// { text: 'UPDATE students SET name = $1, gender = $2', values: ['Thomas', 'M'] }

// node-postgres client
client.query(query);

which is much easier to read and maintain.

[hiddentao]

Very nice. Perhaps I ought to deprecate the the old way of doing parameterised queries.

[mtsr]

Hey, I made a minor mistake in the changes. I fixed it in my fork and could merge it into the pull request if you're considering implementing it.

[mtsr]

There. That should fix my mistake (and the one I made while fixing it).

[hiddentao]

Thank. I'm going to push out version 1.2 now with some other changes, including the ability to load in db engine-specific blocks and builders (Postgres already supported). I'm wondering whether this work should go into that or into the main Squel code.