Model.update(conditions, doc, [options], [callback])

Examples:

MyModel.update({ age: { $gt: 18 } }, { oldEnough: true }, fn);
MyModel.update({ name: 'Tobi' }, { ferret: true }, { multi: true }, function (err, raw) {
  if (err) return handleError(err);
  console.log('The raw response from Mongo was ', raw);
});

Valid options:

• safe (boolean) safe mode (defaults to value set in schema (true))
• upsert (boolean) whether to create the doc if it doesn’t match (false)
• multi (boolean) whether multiple documents should be updated (false) runValidators: if true, runs update validators on this command. Update validators validate the update operation against the model’s schema.
• setDefaultsOnInsert: if this and upsert are true, mongoose will apply the defaults specified in the model’s schema if a new document is created. This option only works on MongoDB >= 2.4 because it relies on MongoDB’s $setOnInsert operator.
• strict (boolean) overrides the strict option for this update
• overwrite (boolean) disables update-only mode, allowing you to overwrite the doc (false)

文档是个好东西

http://mongoosejs.com/docs/api.html#model_Model.update