feat(error): add modified paths to VersionError

backport #6464 to 4.x

Author: paglias

lib/error/version.js

@@ -13,11 +13,13 @@ var MongooseError = require('./');
  * @api private
  */
 
-function VersionError(doc, currentVersion) {
+function VersionError(doc, currentVersion, modifiedPaths) {
+  var modifiedPathsStr = modifiedPaths.join(', ');
   MongooseError.call(this, 'No matching document found for id "' + doc._id +
-    '" version ' + currentVersion);
+    '" version ' + currentVersion + 'modifiedPaths "' + modifiedPathsStr + '"');
   this.name = 'VersionError';
   this.version = currentVersion;
+  this.modifiedPaths = modifiedPaths;
 }
 
 /*!

lib/model.js

@@ -229,6 +229,9 @@ Model.prototype.$__save = function(options, callback) {
       });
     }
 
+    // store the modified paths before the document is reset
+    var modifiedPaths = _this.modifiedPaths();
+
     _this.$__reset();
 
     var numAffected = 0;
@@ -263,7 +266,7 @@ Model.prototype.$__save = function(options, callback) {
 
       if (numAffected <= 0) {
         // the update failed. pass an error back
-        var err = new VersionError(_this, version);
+        var err = new VersionError(_this, version, modifiedPaths);
         return callback(err);
       }
 

test/versioning.test.js

@@ -266,6 +266,7 @@ describe('versioning', function() {
       assert.ok(/No matching document/.test(err), err);
       assert.equal(a._doc.__v, 5);
       assert.equal(err.version, b._doc.__v - 1);
+      assert.deepEqual(err.modifiedPaths, ['numbers', 'numbers.2']);
       a.set('arr.0.0', 'updated');
       var d = a.$__delta();
       assert.equal(a._doc.__v, d[0].__v, 'version should be added to where clause');