Collection of unrelated objects

scarnie · **Joined:** Thu Jun 29, 2006 12:32 pm **Posts:** 22

Hibernate version: 1.2 alpha

Is it possible, using existing NHibernate mapping types, to have a collection of unrelated objects persist to the database? They can serialize their state to a single binary field. Ideally I'd like them to persist as XML (and I know there isn't a mapping for this), so binary serialization is ok to start with.

Cheers,

Stuart

radu · **Joined:** Wed Jun 15, 2005 4:17 am **Posts:** 156

(N)Hibernate is an object-relational mapper - which means it was designed to persist objects in a relational database. What you want to achieve is not persistence to a relational database so your scenario is not covered out of the box by hibernate.

cheers,
radu

jstelly · **Joined:** Fri Jul 22, 2005 4:08 pm **Posts:** 28

In Hibernate they've got a plugin mechanism where you can specify the persister for a specific property to convert value->db and db->value. I haven't found the same thing in NHibernate, so I made an ugly hack in my domain object. The SerializedValue property is only used by NHibernate to map to a binary(x) column:

Code:

        /// <summary>
        /// Gets or sets the value.
        /// </summary>
        /// <value>The value.</value>
        public object Value
        {
            get { return value; }
            set { this.value = value; }
        }

        /// <summary>
        /// Gets or sets the value.
        /// </summary>
        /// <value>The value.</value>
        private byte[] SerializedValue
        {
            get
            {
                if (Value == null)
                    return null;

                BinaryFormatter frmt = new BinaryFormatter();
                using (MemoryStream ms = new MemoryStream())
                {
                    frmt.Serialize(ms, Value);
                    ms.Close();
                    return ms.GetBuffer();
                }
            }
            set
            {
                if (value == null)
                    Value = null;

                BinaryFormatter frmt = new BinaryFormatter();
                using (MemoryStream ms = new MemoryStream(value))
                {
                    Value = frmt.Deserialize(ms);
                }
            }
        }