title: What happens to MongoDB fields which have no corresponding definition in Morphia?
body: <p>I have a project which combines Python's MongoEngine and Java's Morphia.</p>
  
  <p>The Python part is used for the frontend and it uses MongoEngine for document modeling. It stores a lot of information and the frontend is often changing so I will have to add or subtract new fields frequently.</p>
  
  <p>The Java part does some computation task and it relies only on a few fields in the model. To map each field from MongoEngine to Java's Morphia models can be tedious since I won't be using them anyways in the Java part.</p>
  
  <p><em>In the Morphia model, I only want to declare variables/fields which I am going to use.</em>
  So what happens if I don't declare the corresponding variables for the mongo document fields in morphia? 
  Will the original document written by the python part with much more fields be overwritten by Morphia?</p>