MongoDb Compass export db ref as embedded JSON

Question

Is there a way to export a collection with all DBRef Objects embedded in a single JSON?

I tried to export the collection from compass, but it does not resolve the dbrefs to embedded json.

---

Example of the data structures:

Process:

{
    "_id": {
        "$oid": "5f44e89aa1f4c77447629a29"
    },
    "name": "test process",
    "description": "A test configuration for a process",
    "milestones": [{
        "$ref": "milestone",
        "$id": {
            "$oid": "5f5753636b75033a49b7cc7b"
        }
    }, {
        "$ref": "milestone",
        "$id": {
            "$oid": "5f5753636b75033a49b7cc82"
        }
    }]
}

Milestones:

[{
  "_id": {
    "$oid": "5f5753636b75033a49b7cc7b"
  },
  "name": "S1",
  "order": 0,
  "results": [
    {
      "$ref": "resultDefinition",
      "$id": {
        "$oid": "5f5753636b75033a49b7cc79"
      }
    },
    {
      "$ref": "resultDefinition",
      "$id": {
        "$oid": "5f5753636b75033a49b7cc7a"
      }
    }
  ]
},{
  "_id": {
    "$oid": "5f5753636b75033a49b7cc82"
  },
  "name": "S2",
  "order": 1,
  "results": [
    {
      "$ref": "resultDefinition",
      "$id": {
        "$oid": "5f5753636b75033a49b7cc7d"
      }
    },
    {
      "$ref": "resultDefinition",
      "$id": {
        "$oid": "5f5753636b75033a49b7cc7e"
      }
    },
    {
      "$ref": "resultDefinition",
      "$id": {
        "$oid": "5f5753636b75033a49b7cc7f"
      }
    },
    {
      "$ref": "resultDefinition",
      "$id": {
        "$oid": "5f5753636b75033a49b7cc80"
      }
    },
    {
      "$ref": "resultDefinition",
      "$id": {
        "$oid": "5f5753636b75033a49b7cc81"
      }
    }
  ]
}]

Phases:

{
    "_id": {
        "$oid": "5f5753636b75033a49b7cc7c"
    },
    "name": "P1",
    "activityStream": {
        "$ref": "activityStream",
        "$id": {
            "$oid": "5f5755076b75033a49b7cc83"
        }
    }
}

ResultDefinitions:

[{
  "_id": {
    "$oid": "5f5753636b75033a49b7cc79"
  },
  "name": "userresult",
  "resultType": "User"
},{
  "_id": {
    "$oid": "5f5753636b75033a49b7cc7a"
  },
  "name": "planDateResult",
  "resultType": "PlanDate"
},{
  "_id": {
    "$oid": "5f5753636b75033a49b7cc7d"
  },
  "name": "fileResult",
  "resultType": "File"
},{
  "_id": {
    "$oid": "5f5753636b75033a49b7cc7e"
  },
  "name": "dateResult",
  "resultType": "Date"
},{
  "_id": {
    "$oid": "5f5753636b75033a49b7cc7f"
  },
  "name": "textresult",
  "resultType": "Text"
},{
  "_id": {
    "$oid": "5f5753636b75033a49b7cc80"
  },
  "name": "booleanResult",
  "resultType": "Boolean"
},{
  "_id": {
    "$oid": "5f5753636b75033a49b7cc81"
  },
  "name": "numberResult",
  "resultType": "Number"
}]

Relations:

Process can have n milestones. Milestone has one or no Phase. Phase has more nested paths, but not relevant for an example. Milestone can have n ResultDefinitions

Answer 1

You can make a aggregation query and use $out operator, this will copy query result in separate collection, you can modify your query as per your requirement, see the last stage is $out: <collection name>, just provide the name of collection and execute this query, this will copy result in that collection, and you can export that collectoin.

db.process.aggregate([
  { $unwind: "$milestones" },
  {
    $lookup: {
      from: "milestone",
      let: { id: "$milestones.$id" },
      pipeline: [
        { $match: { $expr: { $eq: ["$$id", "$_id"] } } },
        { $unwind: "$results" },
        {
          $lookup: {
            from: "resultDefinition",
            localField: "results.$id",
            foreignField: "_id",
            as: "results"
          }
        },
        { $unwind: "$results" },
        {
          $group: {
            _id: "$_id",
            name: { $first: "$name" },
            order: { $first: "$order" },
            results: { $push: "$results" }
          }
        }
      ],
      as: "milestones"
    }
  },
  { $unwind: "$milestones" },
  {
    $group: {
      _id: "$_id",
      name: { $first: "$name" },
      description: { $first: "$description" },
      milestones: { $push: "$milestones" }
    }
  },

  // you can specify the name of collection that you want
  { $out: "collection name" }
])

Playground