CODEWITHSUNDEEP
c#nhibernatenhibernate-mapping
Pradees
Pradees

Reputation: 201

NHibernate One to Many Mapping and Saving

public class Product : EntityBase<Product, int>, IAggregateRoot
{
    public virtual string ProductName { get; set; }
    public virtual List<ProductDetail> Description { get; set; }
}

public class ProductDetail : EntityBase<ProductDetail, int>, IAggregateRoot
{
    public virtual string Description { get; set; }
    public virtual Product Product { get; set; }
}

The above Product Entity has multiple ProductDetails. My mapping is given below;

public class ProductMap : ClassMapping<Product>
{
    public ProductMap()
    {
        Lazy(false);
        Table("Product");

        Id(x => x.ID, map => { map.Column("ID"); map.Generator(Generators.Native); });
        Property(x => x.ProductName, map => map.NotNullable(true));

        Bag(x => x.Description, m => {
            m.Inverse(true); // Is collection inverse?
            m.Cascade(Cascade.All); //set cascade strategy
            m.Key(k => k.Column(col => col.Name("ProductID"))); //foreign key in Detail table
        }, a => a.OneToMany());
    }
}

public class ProductDetailMap : ClassMapping<ProductDetail>
{
    public ProductDetailMap()
    {
        Lazy(false);
        Table("ProductDetail");

        Id(x => x.ID, map => { map.Column("ID"); map.Generator(Generators.Native); });
        Property(x => x.Description, map => map.NotNullable(false));

        ManyToOne(x => x.Product, x =>
        {
            x.Column("ProductID");
        });
    }
}

When Iam saving this; Iam getting below error.

An exception of type 'NHibernate.PropertyAccessException' occurred in NHibernate.dll but was not handled in user code Additional information: Invalid Cast (check your mapping for property type mismatches);

Upvotes: 1

Views: 788

Answers (1)

Radim K&#246;hler
Radim K&#246;hler

Reputation: 123861

For mapping collections, we must use interfaces (IList<>)

public class Product : EntityBase<Product, int>, IAggregateRoot
{
    public virtual string ProductName { get; set; }
  //public virtual List<ProductDetail>  Description { get; set; }
    public virtual IList<ProductDetail> Description { get; set; }
}

The NHibernate will inject its own IList<> implementation - which is not a child of List... That is needed for proxying... lazy loading

Upvotes: 1

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