Flexible attribute properties patch

[gstreetmedia]

This small change allows a developer to define model attribute properties in anyway they wish. I believe this implementation provides better flexibility in model attribute definitions while maintaining backwards compatibility for those who rely upon the attribute whitelist (likely unknowingly).

attributeWhitelist : "flexible"

can be defined on a per model basis or with config/model.js to make this change globally.

[mikermcneil]

@gstreetmedia hey there! Totally understand where you're coming from- luckily we provide a way to do this now (#95). The conversation in that PR also covers a bit about the reasoning

[gstreetmedia]

meta seems like a good solution for some things. I could also see offering up additional items that would merged into the "whitelist" Sort of saying, yes I know you have your whitelist, but I have my own too. So validate that.

So maybe instead of

attributeWhitelist : flexible

something like

attributeWhitelist : ['isMobilePhone', 'isDivisibleBy',.....]

This would address the issue you outlined, where there were a lot of errors by not validating attribute properties, while still allowing developers to provide an additional whitelist of things they know to be good.

Sudo coded to something like

var validProperties = require('../../accessible/valid-attribute-properties');
....
var validPropertiesToCheck = _.merge(validProperties, schemaCollection.attributeWhitelist)
...
if (_.indexOf(validPropertiesToCheck, propertyName) < 0) {

There are also a lot of validations in the chriso/validator library not covered in waterline. I'd be happy to add some of those and submit a PR. isMoblePhone, isFloat, isCurrency, isBase64...lots of good stuff that would make waterline better.

[danielsharvey]

Further to @mikermcneil's comments above, the solution is probably to use meta property?

To aide others, I've added this to the documentation here balderdashy/sails-docs#1308.

Can probably close this PR?