TypeBasedAggregationOperationContext.getReferenceFor(…) exposes fields with their leaf property name [DATAMONGO-1586]

[spring-projects-issues]

Romuald Coeffier opened DATAMONGO-1586 and commented

Try to use project operation to rename fields and it does not work on root fields.

Document before project operation:

{
  "foo": "v1",
  "fooSub": {
    "sub": "v2"  
  } 
}

Expected result after project:

{
  "bar": "v1",
  "sub": "v2"
}

But get result:

{
  "bar": "null,
  "sub": "v2"
}

Test:

        Foo foo = new Foo("v1", new FooSub("v2"));
        ops.save(foo);

        Aggregation aggregation = Aggregation.newAggregation(
            project()
                .and("foo").as("bar")
                .and("fooSub.sub").as("sub"));
        List<Bar> mappedResults = ops.aggregate(aggregation, Foo.class, Bar.class).getMappedResults();

        assertThat(mappedResults.size()).isEqualTo(1);
        assertThat(mappedResults.get(0).getSub()).isEqualTo("v2"); // ok
        assertThat(mappedResults.get(0).getBar()).isEqualTo("v1"); // failed getBar() returns null instead of "v1"

In debug, Aggregation object is ok:

{ "aggregate" : "__collection__" , "pipeline" : [ { "$project" : { "bar" : "$foo" , "sub" : "$fooSub.sub"}}]}

but after convert to DBObject, $project part contains:

• "bar" -> "1"
• "sub" -> "$fooSub.sub"

---

Affects: 1.7.3 (Fowler SR3), 1.8.6 (Gosling SR6), 1.9.6 (Hopper SR6)

Referenced from: pull request #434, and commits c2bfe42, 174f7f0, 6c6ac6d, 76d6c14, 8df9d30

Backported to: 1.10 GA (Ingalls), 1.9.7 (Hopper SR7)

[spring-projects-issues]

Romuald Coeffier commented

Debug:

TypeBasedAggregationOperationContext#getReferenceFor(Field):
when mapped field is built, name param is not good.

For example

• when field = AggregationField - name: bar, target: foo
• then mappedField = AggregationField - name: foo, target: foo
  And
• when field = AggregationField - name: sub, target: fooSub.sub
• then mappedField = AggregationField - name: sub, target: fooSub.sub

Perhaps field.getName() should be used as first parameter in field(String, String) call ?

[spring-projects-issues]

Mark Paluch commented

This behavior is caused by the TypeBasedAggregationOperationContext, getReferenceFor in particular. The field name (alias) is not considered when building DirectFieldReference.