I have a situation where a patient record will/wont have equipment history records. I am needing to find all patient records that don't have a equipment records or all patients with equipment records that has a field that is not null. The way I am querying below does not work. I don't find any patients without equipment history at all. Any suggestions? The Mappings are correct since I can directly access the records, update, etc. I can't pull back all patients and do a child count since I have a database consisting of over 40,000 records. It would be slow and use too much memory.
Any help would be greatly appreciated. Thanks in advance.
public IList<Patients> GetAllPatientsWithoutDevice(int facilityID, string search)
{
ICriteria query = FluentSessionManager.GetSession()
.CreateCriteria<Patients>()
.Add(Expression.Eq("IsDeleted", false))
.CreateAlias("Facilities", "f")
.Add(Expression.Eq("f.ID", facilityID))
.CreateAlias("EquipmentHistory", "eh") // Tried, inner, left and right joins...
.Add(Expression.Or(
Expression.IsNull("EquipmentHistory"),
Expression.IsNotNull("eh.DateOffPatient")
));
query.AddOrder(new Order("FirstName", true))
.AddOrder(new Order("LastName", true));
return query.List<Patients>();
}
I figured it out... I had to use "IsEmpty" instead of "IsNull".
ICriteria query = FluentSessionManager.GetSession()
.CreateCriteria<Patients>()
.Add(Expression.Eq("IsDeleted", false))
.CreateAlias("Facilities", "f")
.Add(Expression.Eq("f.ID", facilityID))
.CreateAlias("EquipmentHistory", "eh", NHibernate.SqlCommand.JoinType.LeftOuterJoin)
.Add(Expression.Or(
Expression.IsEmpty("EquipmentHistory"),
Expression.IsNotNull("eh.DateOffPatient")
));
Related
I have Three tables A, B, and C. A is a parent table with mutiple child records in B and C.
When I query into A I am getting too many records, as though FNH is doing a Cartesian product.
My query is of the form:
var list = session.Query<A>()
.Fetch(a=> a.Bs)
.Fetch(a=> a.Cs)
Where Bs is the IList property of A, and Cs is the IList property of A.
I should get only as many Bs as relate to A, and only as many Cs relate to A. Instead I get BxC elements of each.
Is there a better way to load these? I am pretty sure I avoided this exact issue in the past, but don't see it in my old example code.
I'm not sure if this is a NH bug or a mapping issue, however the query could be optimised to
session.Query<A>()
.Fetch(a=> a.Bs)
.ToFuture();
var results = session.Query<A>()
.Fetch(a=> a.Cs)
.ToFuture()
.ToList();
You could use a Transformer to get a distinct result:
var list = session.Query<A>()
.Fetch(a=> a.Bs)
.Fetch(a=> a.Cs)
.SetResultTransformer( Transformers.DistinctRootEntity )
This is NH3.2 syntax, for 2.1 you need to use new DistinctRootEntityTransformer() (I think) as parameter to SetResultTransformer instead.
I have an SecurityGroup entity witch has Memebers and Application properties.
Application is a lookup.
So securityGroups is in many-to-many relationship with User table and one-to-many with LookupApplciation (FK)
Now I want to select all application linked to a specific user.
I have follow criteria:
public IList<LookupApplication> GetApplicationByUser(User user)
{
return
this.Session.CreateCriteria(typeof(SecurityGroup), "sg")
.CreateAlias("Members", "u")
.CreateAlias("Application", "al")
.Add(Restrictions.Eq("u.Id", user.Id))
.List<LookupApplication>();
}
It trows an exception
The value "Edi.Advance.Core.Model.Security.SecurityGroup" is not of type "Edi.Advance.Core.Model.Lookups.LookupApplication" and cannot be used in this generic collection.
Parameter name: value
and it is right.
How can I transform the result to IList<LookupApplication>?
Thanks
You can only return the type which you create the criteria from.
The easiest way starting from the code you have will be:
return
this.Session.CreateCriteria(typeof(SecurityGroup), "sg")
.CreateAlias("Members", "u")
.CreateAlias("Application", "al")
.Add(Restrictions.Eq("u.Id", user.Id))
.List<SecurityGroup>()
// get the lookup applications in memory
.SelectMany(x => x.LookupApplications);
This loads all SecurityGroups into memory, even if it only needs the LookupApplications. This might not be an issue when you need them anyway or when they are small.
You could also reverse the query and start from the LookupApplication
return
this.Session.CreateCriteria(typeof(LookupApplication), "la")
// requires navigation path from SecurityGroup to LookupApplication
.CreateCriteria("la.SecurityGroup", "sg")
.CreateAlias("Members", "u")
.CreateAlias("Application", "al")
.Add(Restrictions.Eq("u.Id", user.Id))
.List<LookupApplication>()
Or use HQL, which has some features not available in Criteria, items gets all the items from a collection:
select sg.LookupApplications.items
from SecurityGroup sg inner join sg.Members u
where u.Id = :userId
HQL is actually recommended when you don't have dynamic queries.
Update, from isuruceanu's comment:
Session
.CreateQuery(
#"select sg.Application
from SecurityGroup sg
inner join sg.Members u
where u.Id = :userId")
.SetParameter("userId", user.Id)
.List<LookupApplication>();
It depends on how the SecurityGroup looks like and how LookupApplication looks like.
You could use ResultTransformer like:
.SetResultTransformer(Transformers.AliasToBean<LookupApplication>())
.List<LookupApplication>();
Granted that SecurityGroup has properties matchinig LookupAppliaction, or else you have to project those properties like:
.SetProjection(NHibernate.Criterion.Projections.ProjectionList()
.Add(Projections.Property("Number"), "OrderNumber")
.Add(Projections.Property("CreatedOn"), "CreatedOn")
.Add(Projections.Property("MemeberName"), "Name"))
.SetResultTransformer(Transformers.AliasToBean<LookupApplication>())
.List<LookupApplication>();
I have a simple test object model in which there are schools, and a school has a collection of students.
I would like to retrieve a school and all its students who are above a certain age.
I carry out the following query, which obtains a given school and the children which are above a certain age:
public School GetSchoolAndStudentsWithDOBAbove(int schoolid, DateTime dob)
{
var school = this.Session.CreateCriteria(typeof(School))
.CreateAlias("Students", "students")
.Add(Expression.And(Expression.Eq("SchoolId", schoolid), Expression.Gt("students.DOB", dob)))
.UniqueResult<School>();
return school;
}
This all works fine and I can see the query going to the database and returning the expected number of rows.
However, when I carry out either of the following, it gives me the total number of students in the given school (regardless of the preceding request) by running another query:
foreach (Student st in s.Students)
{
Console.WriteLine(st.FirstName);
}
Assert.AreEqual(s.Students.Count, 3);
Can anyone explain why?
You made your query on the School class and you restricted your results on it, not on the mapped related objects.
Now there are many ways to do this.
You can make a static filter as IanL said, however its not really flexible.
You can just iterate the collection like mxmissile but that is ugly and slow (especially considering lazy loading considerations)
I would provide 2 different solutions:
In the first you maintain the query you have and you fire a dynamic filter on the collection (maintaining a lazy-loaded collection) and doing a round-trip to the database:
var school = GetSchoolAndStudentsWithDOBAbove(5, dob);
IQuery qDob = nhSession.CreateFilter(school.Students, "where DOB > :dob").SetDateTime("dob", dob);
IList<Student> dobedSchoolStudents = qDob.List<Student>();
In the second solution just fetch both the school and the students in one shot:
object result = nhSession.CreateQuery(
"select ss, st from School ss, Student st
where ss.Id = st.School.Id and ss.Id = :schId and st.DOB > :dob")
.SetInt32("schId", 5).SetDateTime("dob", dob).List();
ss is a School object and st is a Student collection.
And this can definitely be done using the criteria query you use now (using Projections)
Unfortunately s.Students will not contain your "queried" results. You will have to create a separate query for Students to reach your goal.
foreach(var st in s.Students.Where(x => x.DOB > dob))
Console.WriteLine(st.FirstName);
Warning: That will still make second trip to the db depending on your mapping, and it will still retrieve all students.
I'm not sure but you could possibly use Projections to do all this in one query, but I am by no means an expert on that.
You do have the option of filtering data. If it there is a single instance of the query mxmissle option would be the better choice.
Nhibernate Filter Documentation
Filters do have there uses, but depending on the version you are using there can be issues where filtered collections are not cached correctly.
I'm having difficulties with multiple joins in the NHibernate Criteria search. Say I had a pet table, and I wanted to return all pets where the pet category was Dog, and the owner gender was female, ordered by the pet birthday. I've tried a bunch of permutations for how I can get this but haven't been able to figure it out. My latest iteration is as follows:
var recentPets = session.CreateCriteria(typeof(Pet))
.AddOrder(Order.Desc("PetBirthday"))
.CreateCriteria("PetType", "pt", JoinType.InnerJoin)
.CreateCriteria("PetOwnerId", "po", JoinType.InnerJoin)
.Add(Expression.Eq("pt.PetTypeName", petType))
.Add(Expression.Eq("po.PersonGender", gender))
.List<Pet>();
Thanks so much for the help!
Is there a reason you are not using the Hibernate/Java persistence query language to perform the query?
select p from Pet p
join p.owner o
where o.gender = :gender
and p.type.name = :petType
order by p.birthday
When paging data, I want to not only return 10 results, but I also want to get the total number of items in all the pages.
How can I get the total count AND the results for the page in a single call?
My paged method is:
public IList GetByCategoryId(int categoryId, int firstResult, int maxResults)
{
IList<Article> articles = Session.CreateQuery(
"select a from Article as a join a.Categories c where c.ID = :ID")
.SetInt32("ID", categoryId)
.SetFirstResult(firstResult)
.SetMaxResults(maxResults)
.List<Article>();
return articles;
}
The truth is that you make two calls. But a count(*) call is very, very cheap in most databases and when you do it after the main call sometimes the query cache helps out.
Your counter call will often be a little different too, it doesn't actually need to use the inner joins to make sense. There are a few other little performance tweaks too but most of the time you don't need them.
I believe you actually can do what you ask. You can retieve the count and the page in one go in code but not in one SQL statement. Actually two queries are send to the database but in one round trip and the results are retrieved as an array of 2 elements. One of the elements is the total count as an integer and the second is an IList of your retrieved entities.
There are 2 ways to do that:
MultyQuery
MultiCriteria
Here is a sample taken from the links below:
IList results = s.CreateMultiQuery()
.Add("from Item i where i.Id > :id")
.Add("select count(*) from Item i where i.Id > :id")
.SetInt32("id", 50)
.List();
IList items = (IList)results[0];
long count = (long)((IList)results[1])[0];
Here is more info on how you can do that. It is really straight forward.
http://ayende.com/Blog/archive/2006/12/05/NHibernateMutliQuerySupport.aspx
http://ayende.com/Blog/archive/2007/05/20/NHibernate-Multi-Criteria.aspx
If you read the 2 articles above you will see that there is a performance gain of using this approach that adds value to the anyway more transparent and clear approach of doing paging with MultiQuery and MultiCriteria against the conventional way.
Please note that recent versions of NHibernate support the idea of futures, so you can do.
var items = s.CreateQuery("from Item i where i.Id > :id")
.SetInt32("id", 50)
.Future<Item>();
var count = s.CreateQuery("select count(*) from Item i where i.Id > :id")
.SetInt32("id", 50)
.FutureValue<long>();
This is a much more natural syntax, and it will still result in a single DB query.
You can read more about it here:
http://ayende.com/Blog/archive/2009/04/27/nhibernate-futures.aspx