Example for transactions in mongodb with GoLang

It can be confusing. Below is a simple example.

if session, err = client.StartSession(); err != nil {
    t.Fatal(err)
}
if err = session.StartTransaction(); err != nil {
    t.Fatal(err)
}
if err = mongo.WithSession(ctx, session, func(sc mongo.SessionContext) error {
    if result, err = collection.UpdateOne(sc, bson.M{"_id": id}, update); err != nil {
        t.Fatal(err)
    }
    if result.MatchedCount != 1 || result.ModifiedCount != 1 {
        t.Fatal("replace failed, expected 1 but got", result.MatchedCount)
    }

    if err = session.CommitTransaction(sc); err != nil {
        t.Fatal(err)
    }
    return nil
}); err != nil {
    t.Fatal(err)
}
session.EndSession(ctx)

You can view full examples here.

This will help you

ctx := context.Background()
client, err := mongo.Connect(ctx, options.Client().ApplyURI("mongodb://localhost:27017"))
if err != nil {
    panic(err)
}

db := client.Database("testdb")
defer db.Client().Disconnect(ctx)
col := db.Collection("testcol")

// transaction
err = db.Client().UseSession(ctx, func(sessionContext mongo.SessionContext) error {
    err := sessionContext.StartTransaction()
    if err != nil {
        return err
    }

    _, err = col.InsertOne(sessionContext, bson.M{"_id": "1", "name": "berry"})
    if err != nil {
        return err
    }

    _, err = col.InsertOne(sessionContext, bson.M{"_id": "2", "name": "gucci"})
    if err != nil {
        sessionContext.AbortTransaction(sessionContext)
        return err
    }
    if err = session.CommitTransaction(sessionContext); err != nil {
        return err
    }
    return nil
})