passing default values when creating new record

Question

the following URL is called on our application to add a new subscription record.

http://example.com/Subscriptions/create?defaultValues={"login_id":1234}

Part of the creationView code is the following:

subscription.creationView()
.title('<h4>Subscriptions <i class="fa fa-angle-right" aria-hidden="true"></i>Create: Subscription</h4>')
.fields([
          nga.field('login_id', 'reference')
         .targetEntity(admin.getEntity('LoginData'))
         .targetField(nga.field('username'))
         .attributes({ placeholder: 'Select Account' })
         .validation({ required: true })
         .singleApiCall(function (login_id) {
            return { 'login_id[]': login_id };
         })
         .label('Username'),

The API call to the LoginData entity is bringing back all the records; what we want is to pass to the API call the login_id value coming from the initial URL.

Something like: http://example.com/api/LoginData?login_id=1234

How do we do that ?