Why mongodb store binary data in the form of base64? - mongodb

Question

I'm trying to learn how mongodb store each and every data type under the hood.
I have found it stores data in BSON format.
In order to store binary data in mongodb, it requires users to convert byte array in base64 then pass that base64 converted string to BinData(subtype,content in base64) class.
What is the reason behind storing binary data in this format. Why mongodb doesn't allow us to store raw binary?

Answer 1

According to the BSON specification, binary is stored as a 32-bit length followed by a type identifier and then by a series of bytes. Not a base64 string, bytes.
A shamelessly copied function from codementor.io shows that in languages that have the capability to handle binary data directly, it can be directly stored:
public class Question
{
[BsonId]
[BsonRepresentation(BsonType.ObjectId)]
public string Id { get; set; }
public string Category { get; set; }
public string Type { get; set; }
public string QuestionHeading { get; set; }
public byte[] ContentImage { get; set; }
public decimal Score { get; set; }
}
public class QuestionService
{
private readonly IMongoCollection<Question> _questions;
public QuestionService(IDatabaseSettings settings)
{
var client = new MongoClient("<YOUR CONNECTION STRING>");
var database = client.GetDatabase("<YOUR DATABASE NAME>");
_questions = database.GetCollection<Question>("Questions");
}
public Question Get(string id)
{
var result = _questions.Find(
q => q.Id == id).FirstOrDefault();
return result;
}
public Question Create(Question question)
{
_questions.InsertOne(question);
return question;
}
}
static void Main(string[] args)
{
Console.WriteLine("Hello World!");
var service = new QuestionService();
// CONVERT JPG TO A BYTE ARRAY
byte[] binaryContent = File.ReadAllBytes("image.jpg");
var question = new Question
{
Category = "Children's Quizzes",
Type = "Puzzles",
QuestionHeading = "Find the cat in the below image",
ContentImage = binaryContent, // Store the byte array in ContentImage property
Score = 10
};
service.Create(question);
}
BinData() is a constructor that permits specifying binary data directly in the source code text.
geeksforgeeks.org has an example for how to Upload and Retrieve Image on MongoDB using Mongoose