title: Long loading data in flask-admin relationship dropdown input
body: <p>How to reduce the amount of data in the related table when editing and inserting item form in Flask-admin.</p>
  
  <p>In my related tables more than 500,000 records ...
  And the flask-admin uploads all the data in the associated drop-down input (example <code>film</code>).... and can not do it.</p>
  
  <p>I created my model mysql innodb through SQLAlchemy.</p>
  
  <p>I can load the data in the parts table? or disable the loading of related data</p>
  
  <pre><code>class LfMailerQueue(db.Model):
      __tablename__ = 'lf_mailer_queue'
  
      mail_id = db.Column(db.Integer, primary_key=True)
      template_id = db.Column(db.ForeignKey(u'lf_mailer.id'))
      user_id = db.Column(db.ForeignKey(u'modx_user_attributes.internalKey'), index=True)
      film_id = db.Column(db.ForeignKey(u'modx_lfvideo_items.id'), index=True)
      email = db.Column(db.String(255))
      fullname = db.Column(db.String(255))
      status = db.Column(db.Integer, nullable=False, server_default=db.FetchedValue())
  
      film = db.relationship(u'ModxLfvideoItem', primaryjoin='LfMailerQueue.film_id == ModxLfvideoItem.id', backref=u'lf_mailer_queues')
      template = db.relationship(u'LfMailer', primaryjoin='LfMailerQueue.template_id == LfMailer.id', backref=u'lf_mailer_queues')
      user = db.relationship(u'ModxUserAttribute', primaryjoin='LfMailerQueue.user_id == ModxUserAttribute.internalKey', backref=u'lf_mailer_queues')
  
  
  class ModxLfvideoItem(db.Model):
      __tablename__ = 'modx_lfvideo_items'
  
      id = db.Column(db.Integer, primary_key=True)
      group = db.Column(db.String(255), nullable=False, unique=True)
  
      def __str__(self):
           return self.group
      ....
  
  
  class ModxUserAttribute(db.Model): 
  
  ....
  </code></pre>