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// Cannot implicitly shard accessed collections because unsupported use of sharded collection
// for target collection of $lookup and $graphLookup.
// @tags: [assumes_unsharded_collection]
// In MongoDB 3.4, $graphLookup was introduced. In this file, we test $graphLookup as applied to the
// Socialite schema example available here: https://github.com/mongodb-labs/socialite
(function() {
"use strict";
var follower = db.followers;
var users = db.users;
follower.drop();
users.drop();
var userDocs = [
{_id: "djw", fullname: "Darren", country: "Australia"},
{_id: "bmw", fullname: "Bob", country: "Germany"},
{_id: "jsr", fullname: "Jared", country: "USA"},
{_id: "ftr", fullname: "Frank", country: "Canada"}
];
userDocs.forEach(function(userDoc) {
assert.commandWorked(users.insert(userDoc));
});
var followers = [{_f: "djw", _t: "jsr"}, {_f: "jsr", _t: "bmw"}, {_f: "ftr", _t: "bmw"}];
followers.forEach(function(f) {
assert.commandWorked(follower.insert(f));
});
// Find the social network of "Darren", that is, people Darren follows, and people who are
// followed by someone Darren follows, etc.
var res = users
.aggregate({$match: {fullname: "Darren"}},
{
$graphLookup: {
from: "followers",
startWith: "$_id",
connectFromField: "_t",
connectToField: "_f",
as: "network"
}
},
{$unwind: "$network"},
{$project: {_id: "$network._t"}})
.toArray();
// "djw" is followed, directly or indirectly, by "jsr" and "bmw".
assert.eq(res.length, 2);
}());
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