Spring Data Mongodb Repositories don't implement inheritance correctly

Question

Having two types of entities, that are mapped to two Java classes in the single MongoDB collection:

@Document
public class Superclass { ... }

@Document(coll         


        

Answer 1

I encounter the same issue.

Take a look at the source code and at my surprise it is kind of not implemented. It adds the Collection name and the entity class but not inserted in the final query the _class property. And after taking a look at it I realized that how Mongo would know that SubClass1 or Subclass2 derived from SuperClass. So I just override the SimpleMongoRepository Class and create my own Factory that put that class instead of the default SimpleMongoRepository

Here what i added:

public MySimpleMongoRepository(MongoEntityInformation<T, ID> metadata, MongoOperations mongoOperations) {

    Assert.notNull(mongoOperations);
    Assert.notNull(metadata);

    this.entityInformation = metadata;
    this.mongoOperations = mongoOperations;
    Reflections reflections = new Reflections("com.cre8techlabs.entity");
    Set<String> subTypes = reflections.getSubTypesOf(entityInformation.getJavaType()).stream().map(Class::getName).collect(Collectors.toSet());
    subTypes.add(entityInformation.getJavaType().getName());
    this.baseClassQuery = Criteria.where("_class").in(subTypes.toArray());
}

And here an example of implementation of a find

public T findOne(ID id) {
    Assert.notNull(id, "The given id must not be null!");
    Query q = getIdQuery(id).addCriteria(baseClassQuery);

    return mongoOperations.findOne(q, entityInformation.getJavaType(), entityInformation.getCollectionName());
}

It works for me, I am just afraid that it take a little longer