spring data mongodb group by

Question

I am using spring data Mongodb in my project and refer the below classes for my query on grouping the results:

Student class:

@Docum         


        

Answer 1

Change your TypedAggregation part to below and add students field to StudentResults

 TypedAggregation<Student> studentAggregation = Aggregation.newAggregation(Student.class,
               Aggregation.group("firstName").
               push("$$ROOT").as("students"));

$$ROOT will push the whole document.

Update:

TypedAggregation<Student> studentAggregation = Aggregation.newAggregation(Student.class,
              Aggregation.group("firstName").
                 push(new BasicDBObject
                       ("_id", "$_id").append
                       ("firstName", "$firstName").append
                       ("lastName", "$lastName")).as("students"));