I made this project to extract the schema from a MongoDB collection(s).

• Set your DB properties in application.properties
• Set the collection you wish to condense in the main class Condensation.
• Optionally create a filter query to match on a subset of documents in the collection.
• Run the app and get the output Json schema for your collection.

Currently the app will output a JSON object representing all the keys in the documents in your collection. Future versions may support an actualy schema format.

Mongo is flexible and it allows you to do things you can't do in a relational database or a strongly typed language like Java. The app will perform validation on your data and by default will output WARN level messages about incongruencies. These situations will be marked with MERGE_CONFLICT and are nothing more than placeholders for you to resolve as you see fit.

• [ "a", 1, {} ] // different types in the same list
• { "a": 1 }, { "a" : {} }// different values for the same key

• DBRefs are not yet supported, they throw an exception:
  • Caused by: org.bson.codecs.configuration.CodecConfigurationException: Can't find a codec for class com.mongodb.DBRef.