Aggregate and paginate over inner array with SpringData MongoDB

I need to paginate over documents contained in arrays of the root documents. For example, to view the first 10 orders with an open status across customers.

Customer structure

{
    "_id": ObjectId("cust-1"),
    "name": "John Doe",
    "orders": [
        {
            "_id": ObjectId("order-1"),
            "status": "open"        
        },
        {
            "_id": ObjectId("order-2"),
            "status": "closed"      
        }
    ]
},
{
    "_id": ObjectId("cust-2"),
    "name": "Jane Doe",
    "orders": [
        {
            "_id": ObjectId("order-3"),
            "status": "open"        
        },
        {
            "_id": ObjectId("order-4"),
            "status": "open"        
        },
        {
            "_id": ObjectId("order-5"),
            "status": "open"        
        },
    ]
}

A page request for page 0, limit 3 should result in John Doe's customer record containing order-1 and Jane Doe's record containing order-3 and order-4. For example

[{
    "_id": ObjectId("cust-1"),
    "name": "John Doe",
    "orders": [
        {
            "_id": ObjectId("order-1"),
            "status": "open"        
        }
    ]
},
{
    "_id": ObjectId("cust-2"),
    "name": "Jane Doe",
    "orders": [
        {
            "_id": ObjectId("order-3"),
            "status": "open"        
        },
        {
            "_id": ObjectId("order-4"),
            "status": "open"        
        },
    ]
}]

To do this, I unwind orders and count, apply page request, group results by _id and project orders and name.

My code

// Operations
UnwindOperation unwindOperation = Aggregation.unwind("orders");
CountOperation countOperation = Aggregation.count().as("total");
SkipOperation skipOperation = Aggregation.skip(pageable.getOffset());
LimitOperation limitOperation = Aggregation.limit(pageable.getPageSize());
GroupOperation groupOperation = Aggregation.group("_id")
    .push("orders").as("orders")
    .push("name").as("name");
ProjectionOperation projectionOperation = Aggregation.project()
        .andInclude("orders")
        .andInclude("name");

// Facet
FacetOperation facetOperation = Aggregation
        .facet(
            unwindOperation,
            countOperation)
        .as("metadata")
        .and(
                unwindOperation,
                skipOperation, 
                limitOperation,
                groupOperation,
                projectionOperation)
        .as("data");

// Aggregation
Aggregation aggregation = Aggregation.newAggregation(
        Aggregation.match(criteria),
        facetOperation
);
AggregationResults<CaseReportFacetResult> result = mongoTemplate.aggregate(aggregation, Customer.class, CustomerFacetResult.class);
CustomerFacetResult fetchResult = result.getUniqueMappedResult();

Problem This works, but in the result set, the name field of the customer is duplicated for each open order. For example Jane Doe's name is returned as "name": "Jane Doe, Jane Doe".

I have removed name from the grouping, but then it is not able to be projected. If removed from both, then the data is not returned at all.

Instead of push("name") ({ $push: "$name" }) which adding the name value into an array, you should use first("name") to get the first/single name value only.

GroupOperation groupOperation = Aggregation.group("_id")
    .push("orders").as("orders")
    .first("name").as("name");