mongodb: get element of nested array by condition [duplicate]

Question

Need to get element of nested array by condition. Origin collection:

[
  {
    code: 134,
    bindings: [
      {
        devId: "71156ce8-ac2b-4282-9f5a-10133441057c",
        userIds: ["9d300b89-29c0-45a8-a4d3-019cfc8f1c7b"]
      },
      {
        devId: "ca33efa1-ec27-4ee1-8117-8b8ab29c1790",
        userIds: ["73e5af2f-fe01-41a3-bebd-6bab895cab58"]
      },
      {
        devId: "a03f5fbd-f279-4182-bfb6-33aba9de5751",
        userIds: ["dc0c5e59-ef1a-44b9-843b-a4ea73bbed2e"]
      }
    ]
  }
]

I try use aggregation function :

db.trigger.aggregate([
  { $match: { _id: "134" } },
  { $unwind: "$bindings" },
  { $match: { "bindings.devId": "ca33efa1-ec27-4ee1-8117-8b8ab29c1790" } },
  { $project: { _id: 0, dateset: 1 } },
  { $out: "bindings" }
]);

but it did not give the desired result. Сan someone tell me what i'm doing wrong?

Sample document has code set to 134 while in your query you're trying to match _id which is a string. Could you show us the desired result ? — mickl
– mickl, Commented May 21, 2019 at 11:51
desired result : { devId: "71156ce8-ac2b-4282-9f5a-10133441057c", userIds: ["9d300b89-29c0-45a8-a4d3-019cfc8f1c7b"] } element of array with specific devId — Yaroslav Lukianenko
– Yaroslav Lukianenko, Commented May 21, 2019 at 12:26

mickl · Accepted Answer · 2019-05-21 12:29:58Z

1

You can try below aggregation, $replaceRoot promotes nested document into root level:

db.collection.aggregate([
    {
        $match: { code: 134 }
    },
    {
        $unwind: "$bindings"
    },
    {
        $match: { "bindings.devId": "71156ce8-ac2b-4282-9f5a-10133441057c" }
    },
    {
        $replaceRoot: { newRoot: "$bindings" }
    }
])

Mongo Playground

answered May 21, 2019 at 12:29

mickl

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1 Comment

Yaroslav Lukianenko Over a year ago

Amazing. Thanks a lot!

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