First stab at promises

lib/findorcreate.js

@@ -1,5 +1,39 @@
 'use strict'
 
+// I know about the deprecation of defer as outlined here:
+// https://developer.mozilla.org/en-US/docs/Mozilla/JavaScript_code_modules/Promise.jsm/Deferred#backwards_forwards_compatible
+// but the proper way as done in https://github.com/Automattic/mongoose/blob/67c465aac5c864c3004d11d49934605037c8f520/lib/query.js#L2226
+// would involve more changes to the code. As a first attempt, less changes is better I think. The proper way would
+// yield the same results, so it's safe to refactor later.
+function Deferred() {
+  /* A method to resolve the associated Promise with the value passed.
+   * If the promise is already settled it does nothing.
+   *
+   * @param {anything} value : This value is used to resolve the promise
+   * If the value is a Promise then the associated promise assumes the state
+   * of Promise passed as value.
+   */
+  this.resolve = null;
+
+  /* A method to reject the associated Promise with the value passed.
+   * If the promise is already settled it does nothing.
+   *
+   * @param {anything} reason: The reason for the rejection of the Promise.
+   * Generally its an Error object. If however a Promise is passed, then the Promise
+   * itself will be the reason for rejection no matter the state of the Promise.
+   */
+  this.reject = null;
+
+  /* A newly created Promise object.
+   * Initially in pending state.
+   */
+  this.promise = new Promise(function(resolve, reject) {
+    this.resolve = resolve;
+    this.reject = reject;
+  }.bind(this));
+  Object.freeze(this);
+}
+
 const defaultOptions = {
 
   /*
@@ -56,6 +90,25 @@ module.exports = function(schema, modelOptions) {
 
     const options = Object.assign({}, defaultOptions, modelOptions, contextOptions)
 
+    var deferred;
+    if (!callback) {
+      deferred = new Deferred()
+      callback = function(err, result, wasUpdated, isNew) {
+        if (err) {
+          deferred.reject(err)
+        } else {
+          if (options.status) {
+            result = {
+              result: result,
+              wasUpdated: wasUpdated,
+              isNew: isNew
+            }
+          }
+          deferred.resolve(result)
+        }
+      }
+    }
+
     this.findOne(query).exec((err, result) => {
       if (err) return callback(err, result, false, false)
       if (result && !additionalFields) return callback(err, result, false, false)
@@ -78,5 +131,7 @@ module.exports = function(schema, modelOptions) {
 
       doc.save(options.saveOptions, err => callback(err, doc, true, !creating))
     })
+
+    return deferred ? deferred.promise : undefined
   }
 }

test/test.js

@@ -73,6 +73,20 @@ describe('#findOrCreate()', () => {
 
   })
 
+  it('creates a new record when just the query is provided, using promises', done => {
+
+    Fruit.findOrCreate({ name: 'Pear', color: 'green' }, null, { status: true }).then((result) => {
+      expect(result.result.name).to.equal('Pear')
+      expect(result.result.color).to.equal('green')
+
+      expect(result.isNew).to.be.true
+      expect(result.wasUpdated).to.be.true
+
+      done()
+    })
+
+  })
+
   it('avoids trying to set mongo query keywords as fields', done => {
 
     Fruit.findOrCreate({ name: 'Watermelon', color: { $exists: true } }, (err, result) => {