Im trying to return a SimpleQuery list that queries a single table and uses IN.
I can get this to work using
return new List<Jobs>(
ActiveRecordMediator<Jobs>.FindAll(Expression.In("ServiceId", ids))
);
However this is really really really slow. So id like to do something like this
SimpleQuery<Job> query =
new SimpleQuery<Job>(#"from Job as j where ? in (j.ServiceId)", ids);
return new List<Job>(query.Execute());
However I cant get the SimpleQuery to work. I cant find any documentation covering this and was hoping someone out there would be able to help.
Thanks
Have a look at the NHibernate HQL documentation here.
I'm guessing from your code, that you're after a HQL query to return all jobs where the job.ServiceID in a list of ids.
Maybe something along the lines,
IQuery q = s.CreateQuery("from Job as j where j.ServiceId in (:serviceIds)");
q.SetParameterList("serviceIds", ids);
BTW, have you heard of the NHibernate Lambda Extensions project?
Below is an example of the IN query done using the the mentioned library. Might be something interesting to look at as an alternative to using HQL.
DetachedCriteria after =
DetachedCriteria.For<Person>()
.Add(SqlExpression.In<Person>(p => p.Name,
new string[] { "name1", "name2", "name3" }));
Related
I am developing an application using ASP.Net MVC and AngularJS. I am not familiar with linq and honestly I don't like it. But I am very familiar with SQL and I can perform complex queries. So, my question is, I want you to look at the below code from my MVC controller:
public JsonResult GetSupervisor()
{
var db = new scaleDBEntities();
return this.Json((from userObj in db.Users
select new
{
supervisorId = userObj.Id,
supervisorfName = userObj.usrFirstName,
supervisorlName = userObj.usrLastName,
})
, JsonRequestBehavior.AllowGet
);
}
How can I change the link query into SQL query?
I believe that I can do something like this:
var blogNames = db.Database.SqlQuery<string>("SELECT Name FROM dbo.Blogs").ToList();
So, if this is right, how can i use in in my return this.Json() for my angular?
Using the example you provided, something like this should work:
return this.Json(new {blogNames});
You're just creating an anonymously-typed object that the JSON serializer can use to produce an object like this:
{
"blogNames": ["blog one", "blog two"]
}
It'll be more complicated if you're trying to produce more complex results from a more complex query. But, well, that's what an ORM is for. I'd echo Gert Arnold's advice to embrace LINQ, rather than just deciding you don't like it because you're not used to it.
I have a object Ob with several fields f1,..,fn (of different types).
Now a list of object is shown in a GridView and I need to implement the sorting method.
The real problem is:
how can I run
(from ob in Ob_list orderby ob.f1 ascending)
when the sorting field is represented by a string (i.e. "f1")?
Unfortunately I am not able to get it with the reflection (I am not able to do something like ob.GetType().GetField("f1"), this is not mapped into sql code).
I have several fields to possibly sort the rows, which is the best&fastest approach to this?
Thank you very much!
LINQ execution is deferred until you actually enumerate over the results or access the "count", etc. Because of this, you can build up your LINQ statement in stages.
The below code is done in C#, but I'm sure the equivalent is possible in VB.NET.
First setup your basic query:
var query = (from ob in Ob_list);
At this point, nothing has actually gone to the database due to deferred execution.
Next, conditionally add your order by components:
if (sortField == "f1")
{
query = query.OrderBy(o => o.f1);
}
else if (sortField == "f2")
{
query = query.OrderBy(o => o.f2);
}
else
{
//...
}
And finally, collect your results
foreach (var item in query)
{
// Process the item
}
I've found this question: How do I specify the Linq OrderBy argument dynamically?
I'm using Entity Framework, so the first answer did not solved my problem. The second one however, worked great!
Hope it helps!
I hope someone can help with this please.
I am trying to query an OLAP Fact table with NHibernate, but am struggling to get it to work. Its seems a simple requirement but I just cant see what the problem could be.
I have a central Fact table with several Dimension tables, one of the Dimensions has a secondary Dimension.
So ERD is. Fact >---1 Factor_Dim >---1 Target_Dim
My NHibernate query is.
facts = session.CreateCriteria(typeof(Fact), "facts")
.CreateAlias("facts.FactorDimension", "factDim", JoinType.InnerJoin)
.CreateAlias("factDim.TargetDimension", "targetDim",JoinType.InnerJoin)
.Add(Restrictions.Eq("targetDim.TargetID", targetId))
.List();
The error is "The multi-part identifier "targetdim2_.TargetID" could not be bound.". The generated SQL does not have the Factor_DIM or Target_DIM tables in the From clause.
Are there any alternative techniques to get this query to work? Id like to stick to this style as opposed to CreateSQLQuery() if possible.
Please help. Thanks.
Linq or QueryOver will be your cleanest solutions. If you are determined to stay with ICriteria you probably would want to wrap each of your entities with a class with common crud methods, it also makes your code access common, so code corrections are done in one place, not over hundres of files or classes.
Theres plenty of projects at http://nhforge.org/wikis/general/open-source-project-ecosystem.aspx which can help you out. I know NhGen ( http://sourceforge.net/projects/nhgen/ ) creates a CRUD class for each entity based on the NHibernate.Burrows GenericDao class with a few CRUD methods. It takes care of all the aliases and joins so queries become as simple as
IMessageDao messageDao = new MessageDao();
// Get All
IList<IMessage> messageList1 dao.FindAll();
// Find using QueryByExample
IList<IMessage> messageList2 = dao.FindByExample(messageDetails, orderBy)).ToList();
// Find using a simple entity query
IList<IMessage> messageList3 = messageDao.Find( new [] { Restrictions.Le(MessageHelper.Columns.Date, dateLastChecked) } );
// Find using a join and a query on said joined entities
IList<IMessage> messageList4 = messageDao.Find
( new []
{
Restrictions.Le(MessageHelper.Columns.Date, dateLastChecked),
Restrictions.Eq(MessageHelper.Columns.IsActive, true))
}, new[]
{
Restrictions.Eq(CategoryHelper.KeyColumns.Rsn, categoryRsn),
Restrictions.Eq(CategoryHelper.Columns.IsActive, true))
}, new []
{
Restrictions.Eq(ChannelHelper.KeyColumns.Rsn, channelRsn),
Restrictions.Eq(ChannelHelper.Columns.IsActive, true))
}
);
Theres plenty of overrides so you can specify your join type or it naturally assumes inner join.
This has been a 2 week battle for me so far with no luck. :(
Let me first state my objective. To be able to search entities which are tagged "foo" and "bar". Wouldn't think that was too hard right?
I know this can be done easily with HQL but since this is a dynamically built search query that is not an option. First some code:
public class Foo
{
public virtual int Id { get;set; }
public virtual IList<Tag> Tags { get;set; }
}
public class Tag
{
public virtual int Id { get;set; }
public virtual string Text { get;set; }
}
Mapped as a many-to-many because the Tag class is used on many different types. Hence no bidirectional reference.
So I build my detached criteria up using an abstract filter class. Lets assume for simplicity I am just searching for Foos with tags "Apples"(TagId1) && "Oranges"(TagId3) this would look something like.
SQL:
SELECT ft.FooId
FROM Foo_Tags ft
WHERE ft.TagId IN (1, 3)
GROUP BY ft.FooId
HAVING COUNT(DISTINCT ft.TagId) = 2; /*Number of items we are looking for*/
Criteria
var idsIn = new List<int>() {1, 3};
var dc = DetachedCriteria.For(typeof(Foo), "f").
.CreateCriteria("Tags", "t")
.Add(Restrictions.InG("t.Id", idsIn))
.SetProjection( Projections.ProjectionList()
.Add(Projections.Property("f.Id"))
.Add(Projections.RowCount(), "RowCount")
.Add(Projections.GroupProperty("f.Id")))
.ProjectionCriteria.Add(Restrictions.Eq("RowCount", idsIn.Count));
}
var c = Session.CreateCriteria(typeof(Foo)).Add(Subqueries.PropertyIn("Id", dc))
Basically this is creating a DC that projects a list of Foo Ids which have all the tags specified.
This compiled in NH 2.0.1 but didn't work as it complained it couldn't find Property "RowCount" on class Foo.
After reading this post I was hopeful that this might be fixed in 2.1.0 so I upgraded. To my extreme disappointment I discovered that ProjectionCriteria has been removed from DetachedCriteria and I cannot figure out how to make the dynamic query building work without DetachedCriteria.
So I tried to think how to write the same query without needing the infamous Having clause. It can be done with multiple joins on the tag table. Hooray I thought that's pretty simple. So I rewrote it to look like this.
var idsIn = new List<int>() {1, 3};
var dc = DetachedCriteria.For(typeof(Foo), "f").
.CreateCriteria("Tags", "t1").Add(Restrictions.Eq("t1.Id", idsIn[0]))
.CreateCriteria("Tags", "t2").Add(Restrictions.Eq("t2.Id", idsIn[1]))
In a vain attempt to produce the below sql which would do the job (I realise its not quite correct).
SELECT f.Id
FROM Foo f
JOIN Foo_Tags ft1
ON ft1.FooId = f.Id
AND ft1.TagId = 1
JOIN Foo_Tags ft2
ON ft2.FooId = f.Id
AND ft2.TagId = 3
Unfortunately I fell at the first hurdle with this attempt, receiving the exception "Duplicate Association Path". Reading around this seems to be an ancient and still very real bug/limitation.
What am I missing?
I am starting to curse NHibernates name at making what is you would think so simple and common a query, so difficult. Please help anyone who has done this before. How did you get around NHibernates limitations.
Forget reputation and a bounty. If someone does me a solid on this I will send you a 6 pack for your trouble.
I managed to get it working like this :
var dc = DetachedCriteria.For<Foo>( "f")
.CreateCriteria("Tags", "t")
.Add(Restrictions.InG("t.Id", idsIn))
.SetProjection(Projections.SqlGroupProjection("{alias}.FooId", "{alias}.FooId having count(distinct t1_.TagId) = " + idsIn.Count,
new[] { "Id" },
new IType[] { NHibernateUtil.Int32 }));
The only problem here is the count(t1_.TagId) - but I think that the alias should be generated the same every time in this DetachedCriteria - so you should be on the safe side hard coding that.
Ian,
Since I'm not sure what db backend you are using, can you do some sort of a trace against the produced SQL query and take a look at the SQL to figure out what went wrong?
I know I've done this in the past to understand how Linq-2-SQL and Linq-2-Entities have worked, and been able to tweak certain cases to improve the data access, as well as to understand why something wasn't working as initially expected.
Im having a problem creating a projection for my nhibernate detachedcriteria object.
I have a class Spa which is linked to table Address.
Address has a field called City which is a string.
public class Spa : IAggregateRoot
{
[BelongsTo("AddressID", Cascade = CascadeEnum.All)]
public Address Address { get; set; }
}
My ultimate goal is to get a distinct list of City names.
If i could get all spas with distinct cities i would be happy too.
All my attempts have been for naught and havent found any helpful posts.
So far i've tried:
DetachedCriteria query = DetachedCriteria.For<Spa>()
.CreateAlias("Address", "A")
query.SetProjection(
Projections.Distinct(Projections.ProjectionList()
.Add(Projections.Alias(Projections.Property("Address"), "A"))));
var Spas = ActiveRecordMediator<Spa>.FindAll(query);
I know the above is not correct, just trying to find somewhere to start.
Any help would be appreciated.
Also any simple projections tutorials would be appreciated, cant seem to find anything straight forward out there.
I also tried, but got cast error, looking into it:
DetachedCriteria query = DetachedCriteria.For<Spa>()
.CreateAlias("Address", "A")
.SetProjection(Projections.Distinct(Projections.Property("A.City")));
It seems to me there are two parts to your question.
1. What should my DetachedCriteria look like?
If you are not performing any other aggregations, GROUP BY should provide the same results as DISTINCT. This is the query I would use:
var query = DetachedCriteria.For<Spa>()
.CreateAlias("Address", "A")
.SetProjection(Projections.GroupProperty("A.City"));
2. How do I execute it with Castle ActiveRecord?
I have never used ActiveRecord, but based on the method signatures, I would expect something like this to work:
var cities = ActiveRecordMediator<string>.FindAll(query);
If you have access to the NHibernate session, you could also execute it this way:
var cities = query.GetExecutableCriteria(session).List<string>();