From 735aa6fbd35cdd8528c89db85f4495411da4a569 Mon Sep 17 00:00:00 2001
From: Wyatt Johnson <wyattjoh@gmail.com>
Date: Fri, 7 Apr 2017 16:40:30 -0600
Subject: [PATCH 1/2] Added new Metadata Service and models

---
 models/asset.js      |  6 ++++
 models/comment.js    |  8 ++++-
 services/metadata.js | 80 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 93 insertions(+), 1 deletion(-)
 create mode 100644 services/metadata.js

diff --git a/models/asset.js b/models/asset.js
index f0046aef0..51ff42705 100644
--- a/models/asset.js
+++ b/models/asset.js
@@ -46,6 +46,12 @@ const AssetSchema = new Schema({
     type: Schema.Types.Mixed,
     default: null
   },
+
+  // Additional metadata stored on the field.
+  metadata: {
+    default: {},
+    type: Object
+  }
 }, {
   versionKey: false,
   timestamps: {
diff --git a/models/comment.js b/models/comment.js
index e6523e45f..0984a0832 100644
--- a/models/comment.js
+++ b/models/comment.js
@@ -75,7 +75,13 @@ const CommentSchema = new Schema({
     default: 'NONE'
   },
   tags: [TagSchema],
-  parent_id: String
+  parent_id: String,
+
+  // Additional metadata stored on the field.
+  metadata: {
+    default: {},
+    type: Object
+  }
 }, {
   timestamps: {
     createdAt: 'created_at',
diff --git a/services/metadata.js b/services/metadata.js
new file mode 100644
index 000000000..a0c433f8b
--- /dev/null
+++ b/services/metadata.js
@@ -0,0 +1,80 @@
+/**
+ * The key must be composed of alpha characters with periods seperating them.
+ */
+const KEY_REGEX = /^(?:[A-Za-z][A-Za-z\.]*[A-Za-z])?(?:[A-Za-z]*)$/;
+
+/**
+ * Allows metadata properties to be set/unset from specific models. It is the
+ * expecatation of this API that the metadata field is either accessed later
+ * directly, or accessed as a result of another database load rather than
+ * this service providing an interface to do so.
+ *
+ * @class MetadataService
+ */
+class MetadataService {
+
+  /**
+   * Parses a key by ensuring that if it is either a string, or an array with
+   * only characters defined in the `KEY_REGEX`
+   *
+   * @static
+   * @param {String|Array} key
+   * @returns {String} string form of the key
+   *
+   * @memberOf Metadata
+   */
+  static parseKey(key) {
+    if (Array.isArray(key)) {
+      key = key.join('.');
+    }
+
+    if ((typeof key !== 'string') || !KEY_REGEX.test(key) || key.length === 0) {
+      throw new Error(`${key} is not valid, only a-zA-Z. allowed`);
+    }
+
+    return ['metadata', key].join('.');
+  }
+
+  /**
+   * Sets an object on the metadata field of an object.
+   *
+   * @static
+   * @param {mongoose.Model} model the mongoose model for the object
+   * @param {String} id the value for the field `id` of the model
+   * @param {String|Array} key key for the metadata field
+   * @param {any} value javascript object to set the value of the metadata to
+   * @returns {Promise} resolves when the update is complete
+   *
+   * @memberOf Metadata
+   */
+  static async set(model, id, key, value) {
+    key = MetadataService.parseKey(key);
+
+    return model.update({id}, {
+      $set: {
+        [key]: value
+      }
+    });
+  }
+
+  /**
+   * Removes the value for the metadata field as the specific key.
+   *
+   * @static
+   * @param {mongoose.Model} model the mongoose model for the object
+   * @param {String} id the value for the field `id` of the model
+   * @param {String|Array} key key for the metadata field
+   * @returns
+   *
+   * @memberOf Metadata
+   */
+  static async unset(model, id, key) {
+    key = MetadataService.parseKey(key);
+
+    return model.update({id}, {
+      $unset: key
+    });
+  }
+}
+
+module.exports = MetadataService;

From 8e33d25a2801c9c0816ccaaa398f9ff4a1261f86 Mon Sep 17 00:00:00 2001
From: Wyatt Johnson <wyattjoh@gmail.com>
Date: Mon, 10 Apr 2017 12:12:07 -0600
Subject: [PATCH 2/2] Some bug fixes + validation updates

---
 graph/hooks.js       | 8 ++++++++
 services/metadata.js | 2 +-
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/graph/hooks.js b/graph/hooks.js
index 499eb60b1..c5b7541b3 100644
--- a/graph/hooks.js
+++ b/graph/hooks.js
@@ -3,6 +3,7 @@ const {
   GraphQLInterfaceType
 } = require('graphql');
 const debug = require('debug')('talk:graph:schema');
+const Joi = require('joi');
 
 /**
  * XXX taken from graphql-js: src/execution/execute.js, because that function
@@ -82,6 +83,8 @@ const decorateWithHooks = (schema, hooks) => forEachField(schema, (field, typeNa
       Object.keys(hooks).forEach((hook) => {
         switch (hook) {
         case 'pre':
+          Joi.assert(hooks.pre, Joi.func().maxArity(4));
+
           debug(`adding pre hook to resolver ${typeName}.${fieldName} from plugin '${plugin.name}'`);
 
           if (typeof hooks.pre !== 'function') {
@@ -91,6 +94,8 @@ const decorateWithHooks = (schema, hooks) => forEachField(schema, (field, typeNa
           acc.pre.push(hooks.pre);
           break;
         case 'post':
+          Joi.assert(hooks.pre, Joi.func().maxArity(5));
+
           debug(`adding post hook to resolver ${typeName}.${fieldName} from plugin '${plugin.name}'`);
 
           if (typeof hooks.post !== 'function') {
@@ -129,6 +134,9 @@ const decorateWithHooks = (schema, hooks) => forEachField(schema, (field, typeNa
       return;
     }
 
+    // Ensure it matches the format we expect.
+    Joi.assert(post, Joi.array().items(Joi.func().maxArity(3)), `invalid post hooks were found for ${typeName}.${fieldName}`);
+
     // Cache the original resolverType function.
     let resolveType = field.resolveType;
 
diff --git a/services/metadata.js b/services/metadata.js
index a0c433f8b..2cabed8b8 100644
--- a/services/metadata.js
+++ b/services/metadata.js
@@ -72,7 +72,7 @@ class MetadataService {
     key = MetadataService.parseKey(key);
 
     return model.update({id}, {
-      $unset: key
+      $unset: {[key]: ''}
     });
   }
 }