Storing blobs/files with OGM

ItsJustMe · **Joined:** Mon Feb 23, 2015 3:53 pm **Posts:** 8

Hi,

Regardless of whether it is a bad way, I'm interested in looking whether it is possible to store blobs/files with Hibernate OGM for MongoDB?
I heard there is a ''GridFS'' for MongoDB, but is it still possible to use this with Hibernate OGM?

Thanks!

Gunnar · **Joined:** Sat Jan 24, 2009 12:46 pm **Posts:** 388

Hi,

Yes, you can store blobs through Hibernate OGM. Just model it as a byte array and add @Lob:

Code:

@Lob
private byte[] lob;

This will be stored as a BinData field in MongoDB. But you need to be aware of the size limit for documents in MongoDB (16 MB).

Hibernate OGM does not support GridFS at this point; It might be an interesting way to store the "overflow" of large entities.

Hth,

--Gunnar

ItsJustMe · **Joined:** Mon Feb 23, 2015 3:53 pm **Posts:** 8

Always appreciate it Gunnar! Thanks for the information.

I will try to work-around the problem and see how to still make use of GridFS while at the same time using Hibernate OGM. ;)

emmanuel · **Posted:** Fri Mar 20, 2015 4:09 am

I think we we end up working on custom user Types, we need to look at this use case as well. i.e. allow people to use the GridFS API.

emmanuel · **Posted:** Fri Mar 20, 2015 4:12 am

Actually, maybe we should offer native GridFS support via a MongoDB specific annotation. Can you open a JIRA? If you are super motivated, you can even give it a try. I don't think it would be too hard and we can guide you. Most of the work will be in one or two methods of MongoDBDialect.

ItsJustMe · **Joined:** Mon Feb 23, 2015 3:53 pm **Posts:** 8

I'm terribly sorry for the late reply. Native GridFS support via a MongoDB specific annotation would be great.
I will open a Jira ticket soon and see what I can do! :)

emmanuel · **Posted:** Mon Mar 30, 2015 7:59 am

Cool :)

mnmh2001 · **Joined:** Thu Nov 13, 2014 8:49 am **Posts:** 9

Hi,

I am new to Hibernate OGM and currently working on a prototype to store images in a mongodb database. I am keen to know if GridFS support is available in any of the OGM versions? secondly could you please direct me towards an example to store it using @lob for image sizes below 4mb

emmanuel · **Posted:** Thu Mar 03, 2016 7:28 am

We did not implement GridFS support yet sorry.
For storing your images something as simple as this should work

Code:

@Entity
public class Asset {
    @Id String id;
    @Lob
    byte[] data;
}

you will put your image bits into the byte[]

mnmh2001 · **Joined:** Thu Nov 13, 2014 8:49 am **Posts:** 9

Thank you.

mnmh2001 · **Joined:** Thu Nov 13, 2014 8:49 am **Posts:** 9

Hi

Using byte[], what is the maximum size of image that can be handled. As byte[] array can only be initialized using a int is the max size restricted to 32Kb?

e.g.
buffer = new byte[int] --- compiles
buffer = new byte[long] -- does not compile

emmanuel · **Posted:** Fri Mar 04, 2016 12:12 pm

No it's limited to 2 147 483 647 (2GB). 32k would be a short. But that's an interesting point I've never considered.

An alternative is to have a custom type to represent extremely long stream of bytes but we don't support custom types yet in Hibernate OGM.
A hacky solution is to represent your big long stream of byts as a Java Serializable object which we would convert to a stream of byte but I don't like this approach.