Allows for other auto increment scenarios other than numeric

[gstreetmedia]

Currently the id for a model requires that it be either "required" or "autoIncrement". However, when setting autoIncrement the value in columnType is ignored. The assumption seems to be that autoIncrement can only be done numerically. This small change allows the developer to determine how the autoincrement should work.

[mikermcneil]

@gstreetmedia thanks!

[mikermcneil]

@gstreetmedia for future reference, worth noting that this approach actually breaks normal usage (because we don't have access to the attributes logical type in the adapter's define() method). I went ahead and adjusted for that -- thankfully it was relatively straightforward to do (if no explicit columnType is set in userland, we make an inference and set e.g. columnType: '_number', etc.)

[gstreetmedia]

I'm glad you revisited this. Almost as soon as I sent of the PR, I realized this should be handled based on columnType. Your solution looks great.

For what its worth, the mysql adapter seems to make this same assumption that autoIncrement is numeric.

From the documentation:

The columnType value is used verbatim in the statement that creates the database column, so you can use it to specify additional options, e.g. varchar(255) CHARACTER SET utf8mb4

Strictly speaking, that isn't currently the case, as both mysql and postgres adapters may still modify the columnType if you set "autoIncrement", "unique", "notNull" to true.

If a complex columnType is present, perhaps there is an easy way to bypass the logic that modifies the columnType (e.g. the addition of UNIQUE, NOT NULL, AUTO_INCREMENT)?

As a side note, i'd love to see a "beforeValidate" callback in Waterline, along with global lifecycle callbacks in /config/models.js. This would allow for the creation of all kinds handy things in a more global manner. In our specific case, we could have inserted a code generated uuid during beforeValidate and left the columnType set to string. I know it's possible to just sub in and "id" during create, but if you have 100's of Model.create({id:uuid.v4()}) instances it becomes challenging to maintain.

[mikermcneil]

Strictly speaking, that isn't currently the case, as both mysql and postgres adapters may still modify the columnType if you set "autoIncrement", "unique", "notNull" to true.

good point, headed out atm, but if you happen to think of this, would welcome a PR to the docs in this area