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/**
* Check that the special $-prefixed field names $ref, $id and $db all work in expressions, $group,
* and $lookup.
*
* Uses $lookup, which doesn't support sharded foreign collection.
* DBRef fields aren't supported in agg pre 4.4.
* @tags: [assumes_unsharded_collection, requires_fcv_44]
*/
(function() {
const coll = db.dbref_in_expression;
const otherColl = db.dbref_in_expression_2;
coll.drop();
otherColl.drop();
assert.commandWorked(otherColl.insert({_id: "id0", x: 1}));
assert.commandWorked(otherColl.insert({_id: "id1", x: 2}));
assert.commandWorked(coll.insert({
_id: 0,
link: new DBRef(otherColl.getName(), "id0", db.getName()),
linkArray: [
new DBRef(otherColl.getName(), "id0", db.getName()),
new DBRef(otherColl.getName(), "id1", db.getName())
]
}));
function projectOnlyPipeline(projection) {
const aggRes = coll.aggregate({$project: projection}).toArray();
const findRes = coll.find({}, projection).toArray();
assert.sameMembers(findRes, aggRes);
return aggRes;
}
// Refer to a DBRef sub-field in a projection.
assert.eq(projectOnlyPipeline({refVal: "$link.$ref"}), [{_id: 0, refVal: otherColl.getName()}]);
assert.eq(projectOnlyPipeline({refVal: "$linkArray.$ref"}),
[{_id: 0, refVal: [otherColl.getName(), otherColl.getName()]}]);
assert.eq(projectOnlyPipeline({idVal: "$link.$id"}), [{_id: 0, idVal: "id0"}]);
assert.eq(projectOnlyPipeline({idVal: "$linkArray.$id"}), [{_id: 0, idVal: ["id0", "id1"]}]);
assert.eq(projectOnlyPipeline({idVal: "$link.$db"}), [{_id: 0, idVal: db.getName()}]);
assert.eq(projectOnlyPipeline({idVal: "$linkArray.$db"}),
[{_id: 0, idVal: [db.getName(), db.getName()]}]);
// Use a DBRef sub-field in an expression.
assert.eq(projectOnlyPipeline({idLen: {$strLenCP: "$link.$id"}}), [{_id: 0, idLen: "id0".length}]);
// Project away DBRef values.
assert.eq(projectOnlyPipeline({link: {$ref: 0}, linkArray: 0}),
[{_id: 0, link: {$id: "id0", $db: db.getName()}}]);
assert.eq(projectOnlyPipeline({link: 0, linkArray: {$id: 0}}), [{
_id: 0,
linkArray: [
{$ref: otherColl.getName(), $db: db.getName()},
{$ref: otherColl.getName(), $db: db.getName()}
]
}]);
// Assigning to a DBRef field.
assert.eq(projectOnlyPipeline({link: {$ref: 1, $id: 1, $db: "someOtherDB"}}),
[{_id: 0, link: new DBRef(otherColl.getName(), "id0", "someOtherDB")}]);
// While not a 'feature' we advertise, it is allowed to assign to top-level DBRef fields.
assert.eq(projectOnlyPipeline({$ref: "$link.$ref"}), [{_id: 0, $ref: otherColl.getName()}]);
// One cannot refer to a top-level DBRef field, however, as it will be interpreted as a variable
// dereference.
const err = assert.throws(() => coll.aggregate({$project: {x: "$$ref"}}).toArray());
assert.eq(err.code, 17276);
// It can be accessed through $$ROOT, however.
assert.eq(coll.aggregate([
// Rather than go through the trouble of inserting a document with a top-level
// $-prefixed field, create one in an intermediate $project stage.
{$project: {"$ref": "hello world"}},
// Make sure that no optimization coalesces the above projection stage with the
// below one.
{$_internalInhibitOptimization: {}},
{$project: {x: "$$ROOT.$ref"}}
])
.toArray(),
[{_id: 0, x: "hello world"}]);
// Do a count (using $group) on a DBRef field.
assert.eq(coll.aggregate({$group: {_id: "$link.$db", count: {$sum: 1}}}).toArray(),
[{_id: db.getName(), count: 1}]);
// Refer to a DBRef field in an accumulator.
assert.eq(coll.aggregate({$group: {_id: "$link.$db", count: {$sum: {$size: "$linkArray.$ref"}}}})
.toArray(),
[{_id: db.getName(), count: 2}]);
// Use $lookup with a DBRef.
// Equality match version.
const lookupEqualityPipeline = [{$lookup: {from: otherColl.getName(),
localField: "link.$id",
foreignField: "_id",
as: "joinedField"}},
{$project: {link: 0, linkArray: 0}}];
assert.eq(coll.aggregate(lookupEqualityPipeline).toArray(),
[{_id: 0, joinedField: [{_id: "id0", x: 1}]}]);
// Foreign pipeline.
const lookupSubPipePipeline = [{$lookup: {from: otherColl.getName(),
let: {idsWanted: "$linkArray.$id"},
pipeline: [{$match: {$expr: {$in: ["$_id", "$$idsWanted"]}}}],
as: "joinedField"}},
{$project: {link: 0, linkArray: 0}}];
assert.eq(coll.aggregate(lookupSubPipePipeline).toArray(),
[{_id: 0, joinedField: [{_id: "id0", x: 1}, {_id: "id1", x: 2}]}]);
(function testGraphLookup() {
// $graphLookup using DBRef.
const graphLookupColl = db.dbref_graph_lookup;
graphLookupColl.drop();
// id0 -> id1 -> id2 -> id0
assert.commandWorked(graphLookupColl.insert(
{_id: "id0", link: new DBRef(graphLookupColl.getName(), "id1", db.getName())}));
assert.commandWorked(graphLookupColl.insert(
{_id: "id1", link: new DBRef(graphLookupColl.getName(), "id2", db.getName())}));
assert.commandWorked(graphLookupColl.insert(
{_id: "id2", link: new DBRef(graphLookupColl.getName(), "id0", db.getName())}));
// id3 -> id4
assert.commandWorked(graphLookupColl.insert(
{_id: "id3", link: new DBRef(graphLookupColl.getName(), "id4", db.getName())}));
assert.commandWorked(graphLookupColl.insert({_id: "id4", link: null}));
const graphLookupPipeline = [{
$graphLookup: {
from: graphLookupColl.getName(),
startWith: "$link.$id",
connectFromField: "link.$id",
connectToField: "_id",
as: "connectedDocuments"
}
},
{$sort: {_id: 1}}];
const res = graphLookupColl.aggregate(graphLookupPipeline).toArray();
// id0, id1, and id2 are all connected.
assert.eq(res[0].connectedDocuments.length, 3);
assert.eq(res[1].connectedDocuments.length, 3);
assert.eq(res[2].connectedDocuments.length, 3);
// id3 is connected to id4.
assert.eq(res[3].connectedDocuments.length, 1);
// id4 is connected to nothing.
assert.eq(res[4].connectedDocuments.length, 0);
assert.eq(res.length, 5);
})();
// Distinct command for a dbref field.
assert.eq(coll.distinct("link.$ref"), [otherColl.getName()]);
assert.eq(coll.distinct("link.$id"), ["id0"]);
assert.eq(coll.distinct("link.$db"), [db.getName()]);
// $merge pipeline.
const thirdColl = db.dbref_in_expression_3;
thirdColl.drop();
assert.commandWorked(thirdColl.insert({_id: 0, a: 1}));
assert.commandWorked(coll.createIndex({"link.$ref": 1}, {unique: true}));
// Merge a document with a 'sentinel' field into the original collection using 'link.$ref' as the
// "on" field.
thirdColl
.aggregate([
{$project: {"link.$ref": otherColl.getName(), "link.$id": "id0", sentinel: "foo"}},
{$merge: {into: coll.getName(), on: "link.$ref", whenMatched: "replace"}}
])
.itcount();
// Check that the merge worked.
assert.eq(coll.find({sentinel: "foo"}).itcount(), 1);
// Merge using an update pipeline.
thirdColl
.aggregate([
{$project: {"link.$ref": otherColl.getName(), "link.$id": "id0", sentinel: "foo"}},
{
$merge: {
into: coll.getName(),
on: "link.$ref",
whenMatched: [{
$project:
{"link.$ref": "otherRef", "link.$id": "otherId", "link.$db": "otherDB"}
}],
whenNotMatched: "discard"
}
}
])
.itcount();
assert.eq(coll.find().toArray()[0], {_id: 0, link: new DBRef("otherRef", "otherId", "otherDB")});
})();
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