Added support for custom _id-s

As per issue #154, if the document to be inserted
already has an _id property, that _id will be used
instead of an automatically generated one.

I updated tests, browser builds and the README.

README.md

@@ -112,7 +112,7 @@ The native types are `String`, `Number`, `Boolean`, `Date` and `null`. You can a
 arrays and subdocuments (objects). If a field is `undefined`, it will not be saved (this is different from 
 MongoDB which transforms `undefined` in `null`, something I find counter-intuitive).  
 
-An `_id` field will be automatically generated by NeDB. It's a 16-characters alphanumerical string that cannot be modified once it has been generated. Unlike with MongoDB, you cannot specify it (that shouldn't be a problem anyway).
+If the document does not contain an `_id` field, NeDB will automatically generated one for you (a 16-characters alphanumerical string). The `_id` of a document, once set, cannot be modified.
 
 Field names cannot begin by '$' or contain a '.'.
 

browser-version/out/nedb.js

@@ -561,7 +561,8 @@ process.nextTick = (function () {
     if (canPost) {
         var queue = [];
         window.addEventListener('message', function (ev) {
-            if (ev.source === window && ev.data === 'process-tick') {
+            var source = ev.source;
+            if ((source === window || source === null) && ev.data === 'process-tick') {
                 ev.stopPropagation();
                 if (queue.length > 0) {
                     var fn = queue.shift();
@@ -683,13 +684,23 @@ Cursor.prototype._exec = function(callback) {
   if (this._sort) {
     keys = Object.keys(this._sort);
     
-    // Going backwards so that the first sort is the last that gets applied
-    for (i = keys.length - 1; i >= 0; i -= 1) {
+    // Sorting
+    var criteria = [];
+    for (i = 0; i < keys.length; i++) {
       key = keys[i];
+      criteria.push({ key: key, direction: self._sort[key] });
+    }
     res.sort(function(a, b) {
-        return self._sort[key] * model.compareThings(model.getDotValue(a, key), model.getDotValue(b, key));
-      });    
+      var criterion, compare, i;
+      for (i = 0; i < criteria.length; i++) {
+        criterion = criteria[i];
+        compare = criterion.direction * model.compareThings(model.getDotValue(a, criterion.key), model.getDotValue(b, criterion.key));
+        if (compare !== 0) {
+          return compare;
+        }
       }
+      return 0;
+    });
     
     // Applying limit and skip
     var limit = this._limit || res.length
@@ -1096,7 +1107,7 @@ Datastore.prototype.prepareDocumentForInsertion = function (newDoc) {
     preparedDoc = [];
     newDoc.forEach(function (doc) { preparedDoc.push(self.prepareDocumentForInsertion(doc)); });
   } else {
-    newDoc._id = customUtils.uid(16);
+    newDoc._id = newDoc._id || customUtils.uid(16);
     preparedDoc = model.deepCopy(newDoc);
     model.checkObject(preparedDoc);
   }

lib/datastore.js

@@ -300,7 +300,7 @@ Datastore.prototype.prepareDocumentForInsertion = function (newDoc) {
     preparedDoc = [];
     newDoc.forEach(function (doc) { preparedDoc.push(self.prepareDocumentForInsertion(doc)); });
   } else {
-    newDoc._id = customUtils.uid(16);
+    newDoc._id = newDoc._id || customUtils.uid(16);
     preparedDoc = model.deepCopy(newDoc);
     model.checkObject(preparedDoc);
   }

test/db.test.js

@@ -198,12 +198,12 @@ describe('Database', function () {
       });
     });
 
-    it('If an _id is already given when we insert a document, dont use it but use an automatic one', function (done) {
+    it('If an _id is already given when we insert a document, use that instead of generating a random one', function (done) {
       d.insert({ _id: 'test', stuff: true }, function (err, newDoc) {
         if (err) { return done(err); }
 
         newDoc.stuff.should.equal(true);
-        newDoc._id.should.not.equal('test');
+        newDoc._id.should.equal('test');
 
         done();
       });