I want to get an object from my database but only populate it with the unique id identifier. I want all other fields to be null...any ideas on how to approach this????
Using NHibernate Linq provider:
Person obj = session.Query<Person>()
.Where(x => x.Id == id)
.Select(x => new Person() { Id = x.Id } )
.SingleOrDefault();
Related
How can I do this in nHibernate using queryover :
SELECT MIN(t.subid)+1 AS NextID
FROM subject t
WHERE NOT EXISTS
(SELECT id FROM subject n WHERE n.subid=t.subid+1)
Currently I have this but its not working because of this statement "SubId+1"
_session.QueryOver(() => subject)
.WithSubquery
.WhereNotExists(
subject
.Where(x => x.SubId==SubId+1)
.Select(x => x.Id)
)
.Select(Projections.ProjectionList()
.Add(Projections.Min<subject>(x => x.SubId)))
.List().First()
One way, using NOT IN instead of NOT EXISTS (results are the same) would be like this (the SQL query would be a bit different, but result will be the same)
Subjectsubject = null;
Subjectinner = null;
var subquery = QueryOver.Of<Subject>(() => inner)
.Select(Projections.SqlProjection(
// important the subid is the column name, not property name
" subid - 1 as innerId" // the trick here is, that we compare
, new[] { "innerId" } // inner ID - 1, with outer ID
, new IType[] { NHibernateUtil.Int32 }))
;
var id = session.QueryOver(() => subject)
.WithSubquery
.WhereProperty(() => subject.ID)
.NotIn(subquery)
.Select(Projections.ProjectionList().Add(Projections.Min<Subject>(s => s.ID)))
.SingleOrDefault<int>();
var id = id + 1 ; // here we increment in C#, instead of projecting that into SQL
Summary: not sure about algorithm you've used, but the trick how to get "subid - 1" is to use projection:
Projections.SqlProjection(
" subid - 1 as innerId" // sql statement
, new[] { "innerId" } // its alias
, new IType[] { NHibernateUtil.Int32 }) // type is int
NOTE: I would expect the last Projections to be MAX
I have a query by QueryOver In Nhibernate 3.1
var q = SessionInstance.QueryOver<Person>()
.Where(p => p.Code == code);
.Select(p => p.Name,p => p.Code);
return q.SingleOrDefault();
This query without select is correct, but with select has a runtime error by this message: Unable to cast object of type 'System.String' to type 'MyNameSpace.Domain.Entities.Person'. How can i select some field of Person?
you need to tell NHibernate explicitly what is the type of your return data since you choose to select some specific properties of your original entity p.Name,P.Code these properties must by returned as of a new type of entity so the new type would be a new object
var query = SessionInstance.QueryOver<Person>()
.Where(p => p.Code == code)
.Select(
p => p.Name,
p => p.Code
)
.List<object>();
this will solve your problem
or if you defined a new entity to hold the new return data as following :
public newPeople
{
public Id { get; set; }
public Nam { get; set; }
}
you can write it like that:
var query = SessionInstance.QueryOver<Person>()
.Where(p => p.Code == code)
.Select(
p => p.Name,
p => p.Code
)
.Select( list =>
new newPeople()
{
Id = (int) list[0],
Name = (string) list[1]
})
.ToList<newPeople>();
I want to do this:
NHibernate.IQueryOver<DataAccess.Domain.Product, DataAccess.Domain.Product> query = session.QueryOver<DataAccess.Domain.Product>();
query = query.Where(x => x.Name == "X");
query = query.Take(1).Skip(3);
List<Product> results = query.List().ToList();
I cant find any help on Skip or Take. The tooltip help (yes I'm that desperate) says that Skip and Take return IQueryOver but the error message says something to the effect "Cant implicitly convert IQueryOver{T} to IQueryOver{T,T}. I don't know what IQueryOver{T,T} is. I didn't ask for one of those anyway.
Try to change your code like this:
NHibernate.IQueryOver<DataAccess.Domain.Product> query = session.QueryOver<DataAccess.Domain.Product>();
query = query.Where(x => x.Name == "X");
query = query.Take(1).Skip(3);
var results = query.List();
Or, even better:
var results = session.QueryOver<DataAccess.Domain.Product>()
.Where(x => x.Name == "X")
.Take(1)
.Skip(3)
.List();
You can check my code here downloading NHibernateQueryOver.
UPDATE:
I think you're missing something. I would suggest you to read this article which has been really helpful for me.
In the paragraph about Associations they say:
An IQueryOver has two types of interest; the root type (the type of entity that the query returns), and the type of the 'current' entity
being queried. For example, the following query uses a join to create
a sub-QueryOver (analagous to creating sub-criteria in the ICriteria
API):
IQueryOver<Cat,Kitten> catQuery =
session.QueryOver<Cat>()
.JoinQueryOver(c => c.Kittens)
.Where(k => k.Name == "Tiddles");
The JoinQueryOver returns a new instance of the IQueryOver than has
its root at the Kittens collection. The default type for restrictions
is now Kitten (restricting on the name 'Tiddles' in the above
example), while calling .List() will return an IList. The type
IQueryOver inherits from IQueryOver.
This is what I do when I want to build multiple filter:
Domain.OrderAddress addressDestination = null;
Domain.Customer customer = null;
Domain.TermsConditionsOfSale termsConditionsOfSale = null;
ICriterion filter1 = Restrictions.Where<Domain.Order>(t => t.Company == "MYCOMPANY");
ICriterion filter2 = Restrictions.Where<Domain.Order>(t => t.WareHouseDelivery == "DEPXX");
ICriterion filter3 = Restrictions.Where<Domain.Order>(t => t.Status == "X");
ICriterion filter4 = Restrictions.Where(() => addressDestination.AddressType == "99");
ICriterion filter5 = Restrictions.Where(() => addressDestination.Province.IsIn(new string[] { "AA", "BB", "CC" }));
ICriterion filter6 = Restrictions.Where(() => termsConditionsOfSale.ReturnedGoodsCode != "01");
var ordersForProvinces = session.QueryOver<Domain.Order>()
.Inner.JoinAlias(t => t.OrderAddresses, () => addressDestination)
.Inner.JoinAlias(t => t.Customer, () => customer)
.Left.JoinAlias(t => t.TermsConditionsOfSale, () => termsConditionsOfSale);
ordersForProvinces
.Where(filter1)
.And(filter2)
.And(filter3)
.And(filter4)
.And(filter5)
.And(filter6);
var Results = ordersForProvinces.Skip(50).Take(20).List();
UPDATE-UPDATE:
NHibernate.IQueryOver<Domain.Person> person = session.QueryOver<Domain.Person>();
var myList = DoSomething(person);
Method:
private static IList<Domain.Person> DoSomething(NHibernate.IQueryOver<Domain.Person> persons)
{
ICriterion filter1 = Restrictions.Where<Domain.Person>(t => t.CompanyName.IsLike("Customer%"));
persons.RootCriteria.Add(filter1);
var x = persons.Skip(1).Take(3).List();
return (x);
}
Ok after several attempts I am stuck on this one!
I am using NHibernate with QueryOver as below. I have a Product and ProductReview as
public class Product
{
....
public virtual IList<ProductReview> CustomerReviews {get;set;}
....
}
public class ProductReview
{
....
public virtual Product Product {get;set;}
....
}
Mapping on Product side is
HasMany(x => x.CustomerReviews).KeyColumn("ProductId").Inverse().Cascade.None().LazyLoad();
The Query is
Product px = null;
ProductReview rev = null;
var result = CurrentSession
.QueryOver<ProductReview>()
.Where(r => r.IsActive && !r.IsDraft)
.Select(
Projections.Property<ProductReview>(r => r.Id).WithAlias(() => rev.Id),
Projections.Property<ProductReview>(r => r.Title).WithAlias(() => rev.Title)
)
.OrderBy(r => r.ReviewDate).Desc()
.TransformUsing(Transformers.AliasToBean<ProductReview>())
.JoinAlias(r => r.Product, () => px)
.Select(
Projections.Property(() => px.UPC).WithAlias(() => px.UPC),
Projections.Property(() => px.FullName).WithAlias(() => px.FullName)
)
.TransformUsing(Transformers.AliasToBean<Product>())
.Take(5)
.List();
The error is:
The value "Reviews.Models.Product" is not of type "Reviews.Models.ProductReview" and cannot be used in this generic collection. Parameter name: value
I really do not want to create another DTO. I would like to get the list of Last 5 new reviews and have it's Product populated (only a few required fields on both entities should be filled).
Is this possible by any means (except raw sql) in NHibernate 3.0?
Product px = null;
ProductReview rev = null;
var result = CurrentSession.QueryOver<ProductReview>()
.Where(r => r.IsActive && !r.IsDraft)
.JoinQueryOver(r => r.Product)
.OrderBy(r => r.ReviewDate).Desc()
.Take(5)
.List();
I'm using the QueryOver api that is part of NHibernate 3.x. I would like to get a row count, but the method I'm using returns all objects and then gets the count of the collection. Is there a way to just return an integer/long value of the number of rows?
I'm currently using:
_session.QueryOver<MyObject>().Future().Count()
After a bit of playing around with the api, this will do it:
_session.QueryOver<MyObject>()
.Select(Projections.RowCount())
.FutureValue<int>()
.Value
If you don't want to return it as a future, you can just get the SingleOrDefault<int>() instead.
Another method
var count = Session.QueryOver<Employer>()
.Where(x => x.EmployerIsActive)
.RowCount();
Another method:
int employerCount = session
.QueryOver<Employer>()
.Where(x => x.EmployerIsActive) // some condition if needed
.Select(Projections.Count<Employer>(x => x.EmployerId))
.SingleOrDefault<int>();
Im using like this:
public int QuantidadeTitulosEmAtraso(Sacado s)
{
TituloDesconto titulo = null;
Sacado sacado = null;
var titulos =
_session
.QueryOver<TituloDesconto>(() => titulo)
.JoinAlias(() => titulo.Sacado, () => sacado)
.Where(() => sacado.Id == s.Id)
.Where(() => titulo.Vencimento <= DateTime.Today)
.RowCount();
}