avoid empty object/array creation

Hi, I find in my documents some fields like:

   ...
   my_array_of_obj_field: [{}],
   my_obj_field: {},
   my_str_field: "",

    ...

(the cause is angularjs in frontend that initializes the empty model)

what’s the best way to avoid storing of those fields?

[vkarpov15]

• If you have an array in your schema, mongoose will create an empty array [] for you by default so you can do .push() and such without explicitly creating the array. To shut this off, overwrite the default array default (requires mongoose 4.4.15 or higher)

var schema = new Schema({
  myArr: { type: [String], default: undefined }
});

• Empty objects shouldn’t happen because of the minimize property, unless you explicitly set minimize: false.
• For strings, set required: true and empty strings will no longer be allowed.

[vkarpov15]

The undefined to null is expected behavior unfortunately, see comments here. Will fix the lowercase issue.