How can I Retrieve the Count of All Linux Users by Selecting Specific Venue IDs in MongoDB using Go?

Retrieve Item List by Checking Multiple Attribute Values in MongoDB in Go

Problem:

Retrieve selected items by identifying multiple conditions in MongoDB, analogous to the IN condition in MySQL:

<code class="sql">SELECT * FROM venuelist WHERE venueid IN (venueid1, venueid2)</code>

Consider the JSON structure:

<code class="json">{
  "_id" : ObjectId("57f940c4932a00aba387b0b0"),
  "tenantID" : 1,
  "date" : "2016-10-09 00:23:56",
  "venueList" : [
    {
      "id" : "VID1212",
      "sum" : [
        {
          "name" : "linux",
          "value" : 12
        },
        {
          "name" : "ubuntu",
          "value" : 4
        }
      ],
      "ssidList" : [
        {
          "id" : "SSID1212",
          "sum" : [
            {
              "name" : "linux",
              "value" : 8
            },
            {
              "name" : "ubuntu",
              "value" : 6
            }
          ],
          "macList" : [
            {
              "id" : "12:12:12:12:12:12",
              "sum" : [
                {
                  "name" : "linux",
                  "value" : 12
                },
                {
                  "name" : "ubuntu",
                  "value" : 1
                }
              ]
            }
          ]
        }
      ]
    },
    {
      "id" : "VID4343",
      "sum" : [
        {
          "name" : "linux",
          "value" : 2
        }
      ],
      "ssidList" : [
        {
          "id" : "SSID4343",
          "sum" : [
            {
              "name" : "linux",
              "value" : 2
            }
          ],
          "macList" : [
            {
              "id" : "43:43:43:43:43:34",
              "sum" : [
                {
                  "name" : "linux",
                  "value" : 2
                }
              ]
            }
          ]
        }
      ]
    }
  ]
}</code>

Task: Retrieve the count of all Linux users by selecting venue IDs 'VID1212' and 'VID4343'.

Solution:

1. Use the aggregation framework to filter documents based on venueList IDs using $match.
2. Unwind venueList and sum subdocument arrays using $unwind.
3. Filter again using $match for desired IDs.
4. Use $group** to aggregate filtered documents, using **$sum accumulator for desired values.
5. Condition using a ternary operator ($cond) to create independent count fields.

<code class="go">// Import the necessary packages.
import (
    "context"
    "fmt"

    "go.mongodb.org/mongo-driver/bson"
    "go.mongodb.org/mongo-driver/bson/primitive"
    "go.mongodb.org/mongo-driver/mongo"
    "go.mongodb.org/mongo-driver/mongo/options"
)

// retrieveItemListByAttributeValues retrieves items based on multiple attribute values in MongoDB.
func retrieveItemListByAttributeValues(client *mongo.Client) {
    // Create a new context.
    ctx := context.Background()

    // Define the pipeline.
    pipeline := mongo.Pipeline{
        {{"$match", bson.D{{"venueList.id", bson.D{{"$in", bson.A{"VID1212", "VID4343"}}}}}}},
        {{"$unwind", "$venueList"}},
        {{"$match", bson.D{{"venueList.id", bson.D{{"$in", bson.A{"VID1212", "VID4343"}}}}}}},
        {{"$unwind", "$venueList.sum"}},
        {
            {"$group", bson.D{
                {"_id", nil},
                {"linux", bson.D{{"$sum", bson.M{"$cond", bson.A{bson.VC.Bool(true), "$venueList.sum.value", 0}}}}}},
                {"ubuntu", bson.D{{"$sum", bson.M{"$cond", bson.A{bson.VC.Bool(true), "$venueList.sum.value", 0}}}}}},
            }},
        },
    }

    // Execute the aggregation pipeline.
    aggRes, err := client.Database("test").Collection("venuelist").Aggregate(ctx, pipeline)
    if err != nil {
        panic(err)
    }

    // Iterate over the results.
    for aggRes.Next(ctx) {
        var result bson.M
        if err := aggRes.Decode(&result); err != nil {
            panic(err)
        }

        // Print the result.
        fmt.Println(result)
    }

    // Close the cursor.
    if err := aggRes.Close(ctx); err != nil {
        panic(err)
    }
}</code>

Alternative Solution:

For improved performance and flexibility, consider the following alternative pipeline:

<code class="go">pipeline := mongo.Pipeline{
    {{"$match", bson.D{{"venueList.id", bson.D{{"$in", bson.A{"VID1212", "VID4343"}}}}}}},
    {{"$unwind", "$venueList"}},
    {{"$match", bson.D{{"venueList.id", bson.D{{"$in", bson.A{"VID1212", "VID4343"}}}}}}},
    {{"$unwind", "$venueList.sum"}},
    {
        {"$group", bson.D{
            {"_id", "$venueList.sum.name"},
            {"count", bson.D{{"$sum", "$venueList.sum.value"}}},
        }},
    },
    {
        {"$group", bson.D{
            {"_id", nil},
            {"counts", bson.D{{"$push", bson.D{
                {"name", "$_id"},
                {"count", "$count"},
            }}}},
        }},
    },
}</code>

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