Persisting Blob Streams with NHibernate

nhibernate stream binary-data blobs
plaureano picture plaureano · Jan 31, 2009 · Viewed 7.3k times · Source

If I have a class declared as:

public class MyPersistentClass
{
     public int ID  { get; set; } 
     public Stream MyData  {get;set; }
}

How can I use NHibernate's mappings to persist the MyData property to and from the database?

Answer

Sebastian Markbåge picture Sebastian Markbåge · Mar 12, 2009

You could use a Stream using a custom type and map it according to your storage needs. But there are some issues with using the Stream object as I mention in my blog series about lazy streaming of BLOBs and CLOBs with NHibernate.

What you really need is a Blob object that in turn can create a Stream to read data from. Since Stream contains information about the position you're reading from and expects to be closed and disposed of it can create some issues when used directly in a domain model.

I would suggest that you take a look at the blog series as well as the source code of the NHibernate.Lob project. It includes various mapping options for just such a problem. A little scarcely documented so far but more is coming.

Related questions

What are the First and Second Level caches in Hibernate?

Can anyone explain in simple words what First and Second Level caching in Hibernate are?

Read More
NHibernate.MappingException: No persister for: XYZ

Now, before you say it: I did Google and my hbm.xml file is an Embedded Resource. Here is the code I am calling: ISession session = GetCurrentSession(); var returnObject = session.Get<T>(Id); Here is my mapping file …

Read More
Best way to convert IList or IEnumerable to Array

I have a HQL query that can generate either an IList of results, or an IEnumerable of results. However, I want it to return an array of the Entity that I'm selecting, what would be the best way of accomplishing …

Read More