database - 在数组中查找 ObjectId

Question

我有商店集合和用户集合，其中包含商店 ID 列表作为字符串。

商店文件示例:

    {
            "_id" : ObjectId("5a0c6797fd3eb67969316ce2"),
            "picture" : "http://placehold.it/150x150",
            "name" : "Genmom",
            "email" : "<a href="https://stackoverflow.com/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="4f232a26232e382e3d2a0f282a21222022612c2022" rel="noreferrer noopener nofollow">[email protected]</a>",
            "city" : "Rabat",
            "location" : {
                    "type" : "Point",
                    "coordinates" : [
                            -6.79387,
                            33.83957
                    ]
            }
    }

用户收集示例:

{
            "_id" : ObjectId("5c04b943ff491824b806686a"),
            "email" : "<a href="https://stackoverflow.com/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="13726a7c66713d787b7a727f53747e727a7f3d707c7e" rel="noreferrer noopener nofollow">[email protected]</a>",
            "password" : "$2a$10$4Wt5Rn6udxREdXCIt3hGb.sKhKUKOlyiYKmLTjYG3SqEPKFSw9phq",
            "likedShops" : [
                    "5a0c6797fd3eb67969316ce2",
                    "5c07ada8ff49183284e509d1",
                    "5c07acc1ff49183284e509d0"
            ],
            "dislikedShops" : [ ]
}

我想返回 LikeShops 的详细信息。

Answer 1

您可以使用下面的 $lookup聚合

db.users.aggregate([
  { "$lookup": {
    "from": "shops",
    "let": { "likedShops": "$likedShops" },
    "pipeline": [
      { "$match": { "$expr": { "$in": ["$_id", "$$likedShops"] }}}
    ],
    "as": "likedShops"
  }}
])

或者，如果您的 ID 是字符串，则使用 $toString与 ObjectIds

的聚合

db.users.aggregate([
  { "$lookup": {
    "from": "shops",
    "let": { "likedShops": "$likedShops" },
    "pipeline": [
      { "$match": { "$expr": { "$in": [{ "$toString": "$_id" }, "$$likedShops"] }}}
    ],
    "as": "likedShops"
  }}
])