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/**
* Tests that using a $graphLookup stage inside of a $facet stage will yield the same results as
* using the $graphLookup stage outside of the $facet stage.
*/
(function() {
"use strict";
load("jstests/aggregation/extras/utils.js"); // For documentEq.
// We will only use one collection, the $graphLookup will look up from the same collection.
var graphColl = db.facetGraphLookup;
// The graph in ASCII form: 0 --- 1 --- 2 3
graphColl.drop();
assert.commandWorked(graphColl.insert({_id: 0, edges: [1]}));
assert.commandWorked(graphColl.insert({_id: 1, edges: [0, 2]}));
assert.commandWorked(graphColl.insert({_id: 2, edges: [1]}));
assert.commandWorked(graphColl.insert({_id: 3}));
// For each document in the collection, this will compute all the other documents that are
// reachable from this one.
const graphLookupStage = {
$graphLookup: {
from: graphColl.getName(),
startWith: "$_id",
connectFromField: "edges",
connectToField: "_id",
as: "connected"
}
};
const projectStage = {
$project: {_id: 1, edges: 1, connected_length: {$size: "$connected"}}
};
const normalResults = graphColl.aggregate([graphLookupStage, projectStage]).toArray();
const facetedResults =
graphColl.aggregate([{$facet: {nested: [graphLookupStage, projectStage]}}]).toArray();
arrayEq(facetedResults, [{nested: normalResults}]);
const sortStage = {
$sort: {_id: 1, "connected._id": 1}
};
const normalResultsUnwound =
graphColl.aggregate([graphLookupStage, {$unwind: "$connected"}, sortStage]).toArray();
const facetedResultsUnwound =
graphColl
.aggregate([{$facet: {nested: [graphLookupStage, {$unwind: "$connected"}, sortStage]}}])
.toArray();
arrayEq(facetedResultsUnwound, [{nested: normalResultsUnwound}]);
}());
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