Using embedded documents in spring data aggregation - mongodb

Question

I have a MongoDB document like this example doc:
{
"_id" : "A",
"articleNumber" : "0123456",
"shopDependentProperties" :
{
"shop" : "DE",
"foo" : "foo",
"bar" : "bar"
}
}
and want to pull out the properties of shopDependentProperties, to have the following result
{
"_id" : "A",
"articleNumber" : "0123456",
"foo" : "foo",
"bar" : "bar"
}
In MongoDB Shell i can solve it this way:
db.test.aggregate(
[
{
$project:
{
_id : "$_id",
articleNumber : "$articleNumber",
foo:"$shopDependentProperties.foo",
bar:"$shopDependentProperties.bar"
}
}
]
)
But: In Spring Data MongoDB i can't extract the embedded document contents.
I tried many combinations, nothing worked. For example:
ProjectionOperation projection = Aggregation.project("_id");
projection.andExpression("shopDependentProperties.foo").as("foo");
projection.andExpression("shopDependentProperties.bar").as("bar");
System.out.println(projection.toDBObject(Aggregation.DEFAULT_CONTEXT));
will ignore the shopDependentProperties.shop stuff and just print out
{ "$project" : { "_id" : 1}}
Any suggestions?
Thx

Answer 1

Haven't tested this, but as of
http://docs.mongodb.org/manual/reference/operator/aggregation/project/
you specify included / excluded fields like this:
db.test.aggregate(
[
{
$project:
{
_id : "$_id",
articleNumber : 1,
"shopDependentProperties.foo": 1,
"shopDependentProperties.bar": 1
}
}
]
)
Further down they explain, how to include embedded documents in the projection result.

Answer 2

I know how to do it in MongoDB, the problem was about doing the same thing in Spring Data.
But it works the same way, why didn't I try that before?
Solution:
ProjectionOperation projection = Aggregation.project(
"brandName",
"$shopDependentProperties.foo",
"$shopDependentProperties.bar" );