MongoDB CRUD application help

Getting Help
1

Hi,
I’m working on a simple CRUD application. The db I’m using is MongoDB, and there’s a problem when it comes to using collection.FindOne, to extract a document from my collection. I can’t get the actual values of the two fields I’ve suffixed with “ID”, namely orderID, and itemID. They store simple integer values like 1, 2, 3, 4 etc. Every time I use FIndOne, I get the correct document, with all the correct values except orderID and itemID. They’re both displayed as 0, for every document. Can someone please help me with this? Thanks.

1 Like
2

Hi Arnav,

It’s been a while since I’ve used MongoDB, but if I remember correctly you need to use something called bson.

It comes as part of the Go MongoDB Driver.

Alternatively, it can be used as a standalone package.

There’s a really good tutorial on the MongoDB website for using MongoDB and BSON with Go.

I hope this was helpful

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3

Thank you for the quick reply. But I’ve been following the same adapter and tutorial. But nothing solves this issue. Even using bson/primitive to pass the correct type, but the issue still persists. Even reading the ObjectID returns ObjectID(“0000000…”), instead of the alphanumeric string seen in MongoDB Compass. Kinda weird.

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4

Hm, that’s strange. So it’s correct in the stored document though right? It’s just went it is read that it doesn’t work?

Edit: Can you provide an example of the code you’re using to read the document?

1 Like
5

It’s correct in the actual DB, but what I’m getting in the result is “all zeroes”.

package main

import (

"context"

"fmt"

"log"

"net/http"

"github.com/gorilla/mux"

"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"

)

type Person struct {

  ID primitive.ObjectID

  Name string

  Age int

}

func main() {

// router setup

r := mux.NewRouter()

// MongoDB initialization

clientOptions := options.Client().ApplyURI("mongodb://localhost:27017")

client, err := mongo.Connect(context.TODO(), clientOptions)

if err != nil {

    log.Fatal(err)

  }

err = client.Ping(context.TODO(), nil)

if err != nil {

    log.Fatal(err)

  }

  fmt.Println("Connected to MongoDB")

collection := client.Database("people").Collection("general")

  r.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {

var result Person

err := collection.FindOne(context.TODO(), bson.M{}).Decode(&result)

if err != nil {

      log.Fatal(err)

    }

// json.NewEncoder(w).Encode(result)

    fmt.Println(result)

  }).Methods("GET")

  http.ListenAndServe("0.0.0.0:8888", r)

}

Output: {ObjectID("000000000000000000000000") Arnav 24}

Actual ObjectID: "5d26190f6f297fc7ef229ea3"

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6

This is an absolute shot in the dark, but try changing bson.M{} to bson.D{{}} and see if the result is the same?

This is incorrect, please see the next comment.

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7

Now I’m getting the right result, thanks. bson.M{} works fine. But I’ve noticed that any name which has “id” or “ID” in the end, isn’t read. Eg: pid is read correctly, but pID isn’t. Are there some rules that I’m missing.

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8

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