Could not compile the mapping document in NHibernate

Question

The exception is:

Could not compile the mapping document: WindowsFormsApplication2.Products.hbm.xml

and the inner exception is:

Persistent class Sample.CustomerService.Domain.Products, Sample.CustomerService. Domain not found

my configuration is:

config file ,i could not paste here because of error ,i did not accept all code hare so i put a link here

and this is mapping file.

And class for mapping is

namespace Sample.CustomerService.Domain
{
    public class Product
    {
        public virtual int Productid { get; set; }
        public virtual string Name { get; set; }
    }
}

and session factory is

public sealed class SessionFactory
{       
    private static volatile ISessionFactory iSessionFactory;
    private static object syncRoot = new object();

    public static ISession OpenSession
    {
        get
        {
            if (iSessionFactory == null)
            {
                lock (syncRoot)
                {
                    if (iSessionFactory == null)
                    {
                        Configuration configuration = new Configuration();
                        configuration.AddAssembly(Assembly.GetCallingAssembly());
                        iSessionFactory = configuration.BuildSessionFactory();
                    }
                }
            }
            return iSessionFactory.OpenSession();
        }
    }
} 

when i try to get record by this code

using (ISession session = SessionFactory.OpenSession)
{
    IQuery query = session.CreateQuery("FROM Products");
    IList<Products> pInfos = query.List<Products>();
    dgView.DataSource = pInfos;
}

it gives me error could not compile mapping document as explained above. i am new to hibernate, i added hibernte from nugget.org by manage nugget pcakage option in visual studio 2012, it added two dlls nhhibernate and Iesi.collections. please help me fix this error, i gave all info in my knowledge.

Answer 1

In your mapping you have Products, and your class is named Product (in singular). So it should be:

<class name="Product" table="Products" lazy="true">

BTW, lazy is default for nhibernate so you can omit it in your mapping. Also if for any chance the table name is the same as the class name you can omit it too, it is a good practice to keep the mapping file content at minimun necesary.

Answer 2

What we would need is mapping like this:

<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2"
    namespace="Sample.CustomerService.Domain" 
    assembly="Sample.CustomerService.Domain"> // expecting same as namespace hre 
    // as the xml sais: class name (C# class name) is Product, not Products
    <class name="Product" table="Products" lazy="true" batch-size="25" >
        // I would also from the beginning suggest to use batch-size="25"

        // name must be equal to C# name, including case sensitivity
        <id name="Productid" column="Product_ID" class="native" />

        // property could be expressed without the column, 
        // if C# name and column name are the same
        <property  not-null="false"  name="Name" />

    </class>    
</hibernate-mapping>

NOTE: Check more about batch fetching here (the batch-size="25" details)

Now, if want to query this - using HQL, we should know, that HQL is built on top of our C# objects. We have to use their exact names:

Chapter 14. HQL: The Hibernate Query Language

NHibernate is equiped with an extremely powerful query language that (quite intentionally) looks very much like SQL. But don't be fooled by the syntax; HQL is fully object-oriented, understanding notions like inheritence, polymorphism and association.

14.1. Case Sensitivity

Queries are case-insensitive, except for names of .NET classes and properties. So SeLeCT is the same as sELEct is the same as SELECT but Eg.FOO is not Eg.Foo and foo.barSet is not foo.BARSET.

And also (I would append) the singular vs plural must fit. So because we have:

public class Product
{
  ...

We must query that like this (suprised that you were able to build that, because Products are not in the code, just Product).

using (ISession session = SessionFactory.OpenSession)
{
    //IQuery query = session.CreateQuery("FROM Products");
    var query = session.CreateQuery("FROM Product"); // just Product

    // here again
    //IList<Products> pInfos = query.List<Products>();
    IList<Product> pInfos = query.List<Product>();
    ...