Add bookshelf-relations (#9252)

no issue

- added https://github.com/TryGhost/bookshelf-relations as dependency
- remove existing tag handling

--- 

* Important: Ensure we trigger parent initialize function

- otherwise the plugin is unable to listen on model events
- important: event order for listeners is Ghost -> Plugin
- Ghost should be able to listen on the events as first instance
- e.g. be able to modify/validate relationships

* Fix tag validation

- we detect lower/update case slugs for tags manually
- this can't be taken over from the plugin obviously
- ensure we update the target model e.g. this.set('tags', ...)

* override base fn: `permittedAttributes`

- ensure we call the base
- put relations on top
- each relation is allowed to be passed
- the plugin will auto-unset any relations to it does not reach the database

* Ensure we run add/edit/delete within a transaction

- updating nested relationships requires sql queries
- all sql statements have to run in a single transaction to ensure we rollback everything if an error occurs
- use es6

core/server/models/base/index.js

@@ -45,6 +45,27 @@ ghostBookshelf.plugin(plugins.pagination);
 // Update collision plugin
 ghostBookshelf.plugin(plugins.collision);
 
+// Manages nested updates (relationships)
+ghostBookshelf.plugin('bookshelf-relations', {
+    allowedOptions: ['context'],
+    unsetRelations: true,
+    hooks: {
+        belongsToMany: {
+            after: function (existing, targets, options) {
+                // reorder tags
+                return Promise.each(targets.models, function (target, index) {
+                    return existing.updatePivot({
+                        sort_order: index
+                    }, _.extend({}, options, {query: {where: {tag_id: target.id}}}));
+                });
+            },
+            beforeRelationCreation: function onCreatingRelation(model, data) {
+                data.id = ObjectId.generate();
+            }
+        }
+    }
+});
+
 // Cache an instance of the base model prototype
 proto = ghostBookshelf.Model.prototype;
 
@@ -119,6 +140,9 @@ ghostBookshelf.Model = ghostBookshelf.Model.extend({
                     return Promise.resolve(self.onValidate.apply(self, args));
                 });
         });
+
+        // NOTE: Please keep here. If we don't initialize the parent, bookshelf-relations won't work.
+        proto.initialize.call(this);
     },
 
     onValidate: function onValidate() {

core/server/models/base/utils.js

@@ -6,7 +6,7 @@ var _ = require('lodash'),
     Promise = require('bluebird'),
     ObjectId = require('bson-objectid'),
     errors = require('../../errors'),
-    tagUpdate, attach;
+    attach;
 
 /**
  * Attach wrapper (please never call attach manual!)
@@ -63,69 +63,4 @@ attach = function attach(Model, effectedModelId, relation, modelsToAttach, optio
         });
 };
 
-tagUpdate = {
-    fetchCurrentPost: function fetchCurrentPost(PostModel, id, options) {
-        return PostModel.forge({id: id}).fetch(_.extend({}, options, {withRelated: ['tags']}));
-    },
-
-    fetchMatchingTags: function fetchMatchingTags(TagModel, tagsToMatch, options) {
-        if (_.isEmpty(tagsToMatch)) {
-            return false;
-        }
-        return TagModel.forge()
-            .query('whereIn', 'name', _.map(tagsToMatch, 'name')).fetchAll(options);
-    },
-
-    detachTagFromPost: function detachTagFromPost(post, tag, options) {
-        return function () {
-            // See tgriesser/bookshelf#294 for an explanation of _.omit(options, 'query')
-            return post.tags().detach(tag.id, _.omit(options, 'query'));
-        };
-    },
-
-    attachTagToPost: function attachTagToPost(Post, postId, tag, index, options) {
-        return function () {
-            // See tgriesser/bookshelf#294 for an explanation of _.omit(options, 'query')
-            return attach(Post, postId, 'tags', [{tag_id: tag.id, sort_order: index}], _.omit(options, 'query'));
-        };
-    },
-
-    createTagThenAttachTagToPost: function createTagThenAttachTagToPost(PostModel, TagModel, post, tag, index, options) {
-        var fields = ['name', 'slug', 'description', 'feature_image', 'visibility', 'parent_id', 'meta_title', 'meta_description'];
-        return function () {
-            return TagModel.add(_.pick(tag, fields), options).then(function then(createdTag) {
-                return tagUpdate.attachTagToPost(PostModel, post.id, createdTag, index, options)();
-            });
-        };
-    },
-
-    updateTagOrderForPost: function updateTagOrderForPost(post, tag, index, options) {
-        return function () {
-            return post.tags().updatePivot(
-                {sort_order: index}, _.extend({}, options, {query: {where: {tag_id: tag.id}}})
-            );
-        };
-    },
-
-    // Test if two tags are the same, checking ID first, and falling back to name
-    tagsAreEqual: function tagsAreEqual(tag1, tag2) {
-        if (tag1.hasOwnProperty('id') && tag2.hasOwnProperty('id')) {
-            return tag1.id === tag2.id;
-        }
-        return tag1.name.toString() === tag2.name.toString();
-    },
-
-    tagSetsAreEqual: function tagSetsAreEqual(tags1, tags2) {
-        // If the lengths are different, they cannot be the same
-        if (tags1.length !== tags2.length) {
-            return false;
-        }
-        // Return if no item is not the same (double negative is horrible)
-        return !_.some(tags1, function (tag1, index) {
-            return !tagUpdate.tagsAreEqual(tag1, tags2[index]);
-        });
-    }
-};
-
 module.exports.attach = attach;
-module.exports.tagUpdate = tagUpdate;