I'm using NHibernate Search for NHibernate 3.0 GA.
I have this code in my product repository:
public IList<Product> Find(string term)
{
var productFields = new[] { "Name", "Description" };
var importance = new Dictionary<String, float>(2) { { "Name", 4 }, { "Description", 1 } };
var analyzer = new StandardAnalyzer();
var parser = new MultiFieldQueryParser(
productFields,
analyzer,
importance);
var query = parser.Parse(term);
var session = Search.CreateFullTextSession(NHibernateSession.Current);
var tx = session.BeginTransaction();
var fullTextQuery = session.CreateFullTextQuery(query);
fullTextQuery.SetFirstResult(0).SetMaxResults(20);
var results = fullTextQuery.List<Product>();
tx.Commit();
return results;
}
In NH Profiler, I can see that a select statement is issued for every product found. What am I missing?
I found this thread from 2009 but presumably this bug has been fixed.
EDIT [06/06/2011]:
My property mappings as far as associations go are as follows:
mapping.HasManyToMany(c => c.Categories)
.Table("CatalogHierarchy")
.ParentKeyColumn("child_oid")
.ChildKeyColumn("oid")
.Cascade.None()
.Inverse()
.LazyLoad()
.AsSet();
mapping.HasMany(c => c.Variants)
.Table("CatalogProducts")
.Where("i_ClassType=2")
.KeyColumn("ParentOID")
.Cascade.SaveUpdate()
.AsSet();
I don't really want to eager fetch all categories.
As NHibernate.Search is unstable, I would use (and I did) Lucene.NET directly from my application - just to ask Lucene for objects' Ids and then load it using Session.Load().
Also you could change LazyLoad settings at class mapping level, not at relationship level.
Hope it helps.
EDIT: you could specify batch-size for relationships, so they wouldn't cause select N+1 problem
Are you referencing any lazy loaded properties in the product list that is returned by this method? If so, you can change the property mapping to "eager fetch".
I solved this in the end. I realised I had not wrapped the whole thing into a transaction. Once I did, the N+1 issue was gone.
Schoolboy error, but hey, you learn by your mistakes.
Related
I'm using by code mappings and trying to map a manytomany. This works fine but I need OrderBy for the child collection items. I noticed this has been omitted (it does exist in the HBM mappings). e.g.
public class Mapping : EntityMapper<Category>
{
public Mapping()
{
Set(x => x.Items, m =>
{
m.Table("ItemCategories");
m.Key(k => k.Column("CategoryId"));
m.Inverse(true);
m.Cascade(Cascade.None);
}, col => col.ManyToMany(m =>
{
m.Columns(x => x.Name("ItemId"));
//m.OrderBy("Score desc"); // missing in Nh4.x?
}));
}
}
Is there a workaround for this? I tried following the suggestion in this article whereby I can set the property before the session factory is built but it has no effect. e.g.
cfg.GetCollectionMapping(typeof(Category).FullName + ".Items").ManyToManyOrdering = "Score desc";
cfg.BuildSessionFactory();
Am I doing something wrong or is OrderBy on manytomany not supported in Nh4?
Also, is it possible to restrict the maximum number of items retrieved in the collection?
Replaced the many to many with one to many and introduced an entity that represents the relationship (followed advice from this article).
This has the upside of allowing you to map the order-by column as well as other columns, and also solved the issue of restricting the number of items in the collection by using the one-to-many's Where() and Filter() clauses.
how can I map a dynamic table name to a entity?
Ex, I can have many tables, all have the same structure, however, has its different name, how can I map this using Fluent NHibernate?
remembering that before compiling I do not know the name of these tables.
Can anyone help me?
What you'll probably need to do is put a place holder in the fluent nhibernate mapping for the table name and then replace it after you build the mappings.
Take a look at the following article and I think the first code sample will give you an idea of what you need to do.
http://ayende.com/blog/3294/dynamic-mapping-with-nhibernate
I was able to do this. Here is a rough example:
var fluentConfiguration = Fluently.Configure(NHibernate.Cfg.Configuration().Configure())
.Mappings(m =>
m.FluentMappings
.AddFromAssemblyOf<OrderMap>()
.Conventions.AddFromAssemblyOf<PascalCaseColumnNameConvention>())
.ProxyFactoryFactory("NHibernate.Bytecode.DefaultProxyFactoryFactory, NHibernate");
var config = fluentConfiguration.BuildConfiguration();
foreach(PersistentClass persistentClass in config.ClassMappings)
{
if(persistentClass.MappedClass == typeof(Order))
{
persistentClass.Table.Name = "Dynamic Table";
}
}
//You could substitute above for each loop with linq unless you have a bunch to replace then use foreach
//config.ClassMappings.First(x => x.MappedClass == typeof(Order)).Table.Name = "Dynamic Table";
var sessionFactory = config.BuildSessionFactory();
using(ISession session = sessionFactory.OpenSession())
{
Order order = session.Query<Order>().FirstOrDefault();
}
I'm new to Fluent Hibernate And I'm stuck with a problem I want to get the email id of a user by using his user name means I want to implement the following code using fluent Hibernate
Select emailId from Table where username="User"
I tried the following code but its not give me what i want
public string ForgetPassword(string user)
{
var factory = CreateSessionFactory();
using (var session = factory.OpenSession())
{
var getEmail = session.Query<ClsAccountBL>()
Select(u => u.Email).Where(u => u.User == user).ToString();
return getMail;
}
}
Please help me to solve this
Instead of .ToString() use FirstOrDefault(). The LINQ does not return "single" element.
This NHibernate blog entry notes how detached QueryOver queries (analogous to DetachedCriteria) can be created (using QueryOver.Of<T>()). However, looking this over, it doesn't look analogous to me at all.
With DetachedCriteria, I would create my instance and set it up however I need, and afterwards call GetExecutableCriteria() to then assign the session and execute the query. With the "detached" QueryOver, most of the API is unavailable (ie, to add restrictions, joins, ordering, etc...) until I call GetExecutableQueryOver, which requires takes an ISession or IStatelessSession, at which point you are no longer disconnected.
How do you work with detached QueryOver instances?
EDIT:
Actual problem was related to how I'm storing the detached QueryOver instance:
public class CriteriaQuery<T>
{
internal protected QueryOver<T> _QueryOver { get; set; }
public CriteriaQuery()
{
_QueryOver = QueryOver.Of<T>();
}
// Snip
}
It should be a QueryOver<T, T>.
I'm using NHibernate 3.1.0.4000. The following code compiles successfully:
Employee salesRepAlias = null;
var query = QueryOver.Of<Customer>()
.JoinAlias(x => x.SalesRep, () => salesRepAlias)
.Where(x => x.LastName == "Smith")
.Where(() => salesRepAlias.Office.Id == 23)
.OrderBy(x => x.LastName).Asc
.ThenBy(x => x.FirstName).Asc;
return query.GetExecutableQueryOver(session)
.List();
This illustrates using restrictions, joins, and ordering on a detached QueryOver just like you would with a regular one.
Could you please post the code that demonstrates the API features that are unavailable?
Using Castle ActiveRecord / NHibernate: Is there a way you can force an ICriterion on all queries on a table?
For example, a good amount of of my tables have a "UserId" column. I might want to ensure that I am always selecting rows for the logged in user. I can easily create an ICriterion object, but I am forced to supply it for different methods: FindAll(), FindFirst(), FindLast() etc.
Is there a way to force a WHERE clause on all queries to a Castle ActiveRecord?
I finally found a great solution (using filters). Since Castle AR does not have any native API for mapping to NHibernate filters, this part was pretty much undocumented. So here goes.
This example filter, will make sure you will never get news more than a year old, no matter what kind of query you use on the ActiveRecord. You can probably think of more practical applications for this.
First, create an ActiveRecord "News".
Use the following code before you initialize ActiveRecordStarter.
ActiveRecordStarter.MappingRegisteredInConfiguration += MappingRegisteredInConfiguration;
Castle.ActiveRecord.Framework.InterceptorFactory.Create = () => { return new EnableFiltersInterceptor(); };
Then, add the missing function and class:
void MappingRegisteredInConfiguration(Castle.ActiveRecord.Framework.ISessionFactoryHolder holder)
{
var cfg = holder.GetConfiguration(typeof (ActiveRecordBase));
var typeParameters = new Dictionary<string, IType>
{
{"AsOfDate", NHibernateUtil.DateTime}
};
cfg.AddFilterDefinition(new FilterDefinition("Latest", "", typeParameters));
var mappings = cfg.CreateMappings(Dialect.GetDialect(cfg.Properties));
var newsMapping = cfg.GetClassMapping(typeof (News));
newsMapping.AddFilter("Latest", ":AsOfDate <= Date");
}
public class EnableFiltersInterceptor : EmptyInterceptor
{
public override void SetSession(ISession session)
{
session.EnableFilter("Latest").SetParameter("AsOfDate", DateTime.Now.AddYears(-1));
}
}
And voila! Queries on News, e.g. FindAll(), DeleteAll(), FindOne(), Exists(), etc. will never touch entries more than a year old.
The closest thing would be using filters. See http://ayende.com/Blog/archive/2009/05/04/nhibernate-filters.aspx