Add new MongoSchemaCollection class that manages schemas for all collections.

src/Adapters/Storage/Mongo/MongoSchemaCollection.js

@@ -0,0 +1,58 @@
+
+import MongoCollection from './MongoCollection';
+
+function _mongoSchemaQueryFromNameQuery(name: string, query) {
+  return _mongoSchemaObjectFromNameFields(name, query);
+}
+
+function _mongoSchemaObjectFromNameFields(name: string, fields) {
+  let object = { _id: name };
+  if (fields) {
+    Object.keys(fields).forEach(key => {
+      object[key] = fields[key];
+    });
+  }
+  return object;
+}
+
+export default class MongoSchemaCollection {
+  _collection: MongoCollection;
+
+  constructor(collection: MongoCollection) {
+    this._collection = collection;
+  }
+
+  getAllSchemas() {
+    return this._collection._rawFind({});
+  }
+
+  findSchema(name: string) {
+    return this._collection._rawFind(_mongoSchemaQueryFromNameQuery(name), { limit: 1 }).then(results => {
+      return results[0];
+    });
+  }
+
+  // Atomically find and delete an object based on query.
+  // The result is the promise with an object that was in the database before deleting.
+  // Postgres Note: Translates directly to `DELETE * FROM ... RETURNING *`, which will return data after delete is done.
+  findAndDeleteSchema(name: string) {
+    // arguments: query, sort
+    return this._collection._mongoCollection.findAndRemove(_mongoSchemaQueryFromNameQuery(name), []).then(document => {
+      // Value is the object where mongo returns multiple fields.
+      return document.value;
+    });
+  }
+
+  addSchema(name: string, fields) {
+    let mongoObject = _mongoSchemaObjectFromNameFields(name, fields);
+    return this._collection.insertOne(mongoObject);
+  }
+
+  updateSchema(name: string, update) {
+    return this._collection.updateOne(_mongoSchemaQueryFromNameQuery(name), update);
+  }
+
+  upsertSchema(name: string, query: string, update) {
+    return this._collection.upsertOne(_mongoSchemaQueryFromNameQuery(name, query), update);
+  }
+}

src/Adapters/Storage/Mongo/MongoStorageAdapter.js

@@ -1,9 +1,12 @@
 
 import MongoCollection from './MongoCollection';
+import MongoSchemaCollection from './MongoSchemaCollection';
 
 let mongodb = require('mongodb');
 let MongoClient = mongodb.MongoClient;
 
+const MongoSchemaCollectionName = '_SCHEMA';
+
 export class MongoStorageAdapter {
   // Private
   _uri: string;
@@ -38,6 +41,12 @@ export class MongoStorageAdapter {
       .then(rawCollection => new MongoCollection(rawCollection));
   }
 
+  schemaCollection(collectionPrefix: string) {
+    return this.connect()
+      .then(() => this.adaptiveCollection(collectionPrefix + MongoSchemaCollectionName))
+      .then(collection => new MongoSchemaCollection(collection));
+  }
+
   collectionExists(name: string) {
     return this.connect().then(() => {
       return this.database.listCollections({ name: name }).toArray();

src/Controllers/DatabaseController.js

@@ -33,6 +33,10 @@ DatabaseController.prototype.adaptiveCollection = function(className) {
   return this.adapter.adaptiveCollection(this.collectionPrefix + className);
 };
 
+DatabaseController.prototype.schemaCollection = function() {
+  return this.adapter.schemaCollection(this.collectionPrefix);
+};
+
 DatabaseController.prototype.collectionExists = function(className) {
   return this.adapter.collectionExists(this.collectionPrefix + className);
 };