Struggling to convert a MongoDB singleResult object into Go struct - mongodb

Question

I tried to follow documentation here and here but had no luck.
I want to get a singleResult from FindOne on the Collection named moviesCollection and then use Decode or Unmarshal to put those values into a struct. The values in the struct JSONData are exactly the same as in each Document
I am using the official mongodb driver github.com/mongodb/mongo-go-driver
Here is an example of what I have tried:
mongoContext, cancelContext := context.WithTimeout(context.Background(), 10*time.Second)
defer cancelContext()
mongoClient, _ := mongo.Connect(mongoContext, options.Client().ApplyURI("mongodb://localhost:27017"))
moviesCollection := mongoClient.Database("Entertainment").Collection("Movies")
moviesCollection.InsertOne(mongoContext, bson.M{"_id": "Deadpool", "Path": "path/to/file"})
singleResult := moviesCollection.FindOne(mongoContext, bson.M{"_id": "Deadpool"})
if singleResult.Err() != nil {
log.Println("Find error: ", singleResult.Err())
}
JSONData := struct {
Path string `json:"Path"`
}{}
decodeError := singleResult.Decode(&JSONData)
if decodeError != nil {
log.Println("Decode error: ", decodeError)
}
fmt.Println("Path: ", JSONData.Path)
However no errors are produced and JSON.Path produces and empty string.
I have also tried using bson.D{{"_id", "Deadpool"}} instead of bson.M{"_id": "Deadpool"}
I can confirm that JSON.Path is not empty string as I have checked the database natively using MongoDB Compass. The entry contains the following:
{"_id":"Deadpool","Path":"path/to/file"}

Answer 1

Internally, MongoDB uses bson. Change your struct as below should work.
From
JSONData := struct {
Path string `json:"Path"`
}{}
to
JSONData := struct {
Path string `bson:"Path"`
}{}

Answer 2

Hey so as simagix mentioned you should be able to change your tag from JSON to bson:
`bson:"Path"`
Another option, incase you need to obtain a more generic result is to pass it a D object like so:
JSONData := &bson.D{}
decodeError := singleResult.Decode(JSONData)
You can then obtain all the information through a map using the JSON.Data.Map function.

Answer 3

If you are using mongo-go-driver >= v.0.1.0 then, taking a look to the go-doc it looks pretty straightforward:
filter := bson.D{{"hello", "world"}}
err := collection.FindOne(context.Background(), filter).Decode(&result)
if err != nil { return err }
// do something with result...
So, what you need is:
package main
import (
"context"
"github.com/mongodb/mongo-go-driver/bson"
"github.com/mongodb/mongo-go-driver/mongo
)
func main() {
ctx := context.Background()
client, err := mongo.NewClient("mongodb://localhost:27017")
if err != nil {
...
}
if err := client.Connect(ctx); err != nil {
...
}
defer client.Disconnect(ctx)
collection := client.Database("myDb").Collection("movies")
filter := bson.D{{"_id", "sometitle"}}
var result JSONData
err := collection.FindOne(ctx, filter).Decode(&result)
if err != nil {
...
}
// Do Something cool here
}
I see you are using Title to filter the doc. Pay attention.