Question 385640 in Mongodb Question posted in
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Getting client disconnected error when connecting to mongodb from go

I am trying to connect to mongodb from go. My func for getting me the collection

func dbConnection() *mongo.Collection {
    serverAPI := options.ServerAPI(options.ServerAPIVersion1)
    opts := options.Client().ApplyURI("mongodb+srv://username:pwd@domain").SetServerAPIOptions(serverAPI)
    client, err := mongo.Connect(context.TODO(), opts)
    if err != nil {
        panic(err)
    }
    defer func() {
        if err = client.Disconnect(context.TODO()); err != nil {
            panic(err)
        }
    }()
    collection := client.Database("testdb").Collection("test")
    return collection
}

Calling Code:

func sortByName(colls *mongo.Collection) {
    coll := dbConnection()
    filter := bson.D{{Key: "name", Value: "joe"}}
    opts := options.Find().SetSort(bson.D{{Key: "name", Value: 1}})
    cursor, err := coll.Find(context.TODO(), filter, opts)
    if err != nil {
        fmt.Printf("err in FIND: %vn", err)
    }
    var results []bson.D
    err = cursor.All(context.TODO(), &results)
    if err != nil {
        fmt.Printf("err in cursor: %vn", err)
    }
    for _, result := range results {
        fmt.Printf("result: %vn", result)
    }
}

when I am calling this and trying to use the collection I am getting

err in FIND: client is disconnected
panic: runtime error: invalid memory address or nil pointer dereference
    panic: runtime error: invalid memory address or nil pointer dereference
    panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x48 pc=0xcb7b33b]

Any help appreciated.

Tags:

2

Answers


  1. 0

    In your code

        defer func() {
        if err = client.Disconnect(context.TODO()); err != nil {
            panic(err)
        }
    }()

    this will call after the code reaches end of dbConnection function.
    so it will disconnect from mongodb.

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  2. 0

    to fix this, manage the MongoDB client’s lifecycle at a higher level in your application. Connect to the MongoDB client when the program starts and disconnect when it finishes.

        var client *mongo.Client

func init() {
    var err error
    opts := options.Client().ApplyURI("mongodb+srv://username:pwd@domain")
    client, err = mongo.Connect(context.TODO(), opts)
    if err != nil {
        panic(err)
    }
}

func dbConnection() *mongo.Collection {
    return client.Database("testdb").Collection("test")
}

func sortByName() {
    coll := dbConnection()
    filter := bson.D{{Key: "name", Value: "joe"}}
    opts := options.Find().SetSort(bson.D{{Key: "name", Value: 1}})
    cursor, err := coll.Find(context.TODO(), filter, opts)
    if err != nil {
        fmt.Printf("err in FIND: %vn", err)
    }
    var results []bson.D
    err = cursor.All(context.TODO(), &results)
    if err != nil {
        fmt.Printf("err in cursor: %vn", err)
    }
    for _, result := range results {
        fmt.Printf("result: %vn", result)
    }
}

func main() {
    defer func() {
        if err := client.Disconnect(context.TODO()); err != nil {
            panic(err)
        }
    }()
    sortByName()
}
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