Add before and after hooks

[eduardoboucas]

This is an addition to #27, with the implementation of before and after hooks, as discussed with @jimlambie. I've pushed this to a separate branch so it's easier to see all the changes and decide if there's anything that needs to be amended before merging back to the feature/hooks branch.

The current create, update and delete hooks, which are fired before the events take place, were renamed to beforeCreate, beforeUpdate and beforeDelete, respectively. The hooks afterCreate, afterUpdate and afterDelete are now introduced by this PR.

Before hooks are always fired, whereas after hooks only fire after and if an operation is successful.

Overview

The following data is passed to each type of hook:

• beforeCreate:
  • obj: Fields sent in the request
  • data:
    • options: Hook options
• afterCreate:
  • obj: Document created in the database
  • data:
    • options: Hook options
• beforeUpdate:
  • obj: Update query sent in the request
  • data:
    • options: Hook options
    • updatedDocs: Documents affected by the update
• afterUpdate:
  • obj: Updated documents
  • data:
    • options: Hook options
• beforeDelete:
  • obj: Delete query sent in the request
  • data:
    • options: Hook options
• afterDelete:
  • obj: Delete query sent in the request
  • data:
    • options: Hook options

Testing

The following hook may be useful to get a better idea of when exactly each hook type is fired and what data it receives, as it logs to the console its internals every time it gets called:

workspace/hooks/showInfo.js

module.exports = function (obj, type, data) {
  console.log('');
  console.log('**** HOOK ***');
  console.log('Type:', type);
  console.log('Payload:', obj);
  console.log('Additional data:', data);
  console.log('');

  return obj;
};

And then enable it in a model:

workspace/collections/vjoin/testdb/collection.users.json

"hooks": {
  "beforeCreate": ["showInfo"],
  "afterCreate": ["showInfo"],
  "beforeUpdate": ["showInfo"],
  "afterUpdate": ["showInfo"],
  "beforeDelete": ["showInfo"],
  "afterDelete": ["showInfo"]
}

Let me know your thoughts. (cc @josephdenne @jimlambie)

[jimlambie]

@eduardoboucas you can see I've had to duplicate the hook apply method here, when we have been passed an array of documents.

The same has been done for the afterCreate hooks.

If you can make this look actually tidy, we'll be all set to merge 👍

Thanks!