I would like to make this query:
Session.Linq<User>().Where(u => u.Payments.Count(p => p.Date != null) > 0);
In plain English I want to get all the users that has at least one payment with the date specified.
When I run the sample code I get a System.ArgumentException with the message:
System.ArgumentException : Could not find a matching criteria info provider to: this.Id = sub.Id
Do you know a solution to this problem?
It would also be very helpful if someone could provide the same query with the NHibernate Query by Criteria API.
I'm not sure if this will work in your particular case, but I would use the .Any() extension to clean up the linq query a bit; for example:
Session.Linq<User>().Where(u => u.Payments.Any(p => p.Date != null));
I think something like it:
Customer customerAlias = null;
criteria = CurrentSession.CreateCriteria(typeof(User), () => customerAlias);
if (searchCriteria.OrdersNumber.HasValue)
{
ICriteria paymentsCriteria = criteria.CreateCriteria<Customer>(x => x.Payments);
DetachedCriteria paymentsCount = DetachedCriteria.For<Payment>();
paymentsCount.SetProjection(Projections.RowCount());
paymentsCount.Add(SqlExpression.NotNull<Payment>(x => x.Date));
paymentsCount.Add<Payment>(x => x.Customer.Id == customerAlias.Id);
paymentsCriteria.Add(Subqueries.Gt(1, paymentsCount));
}
return criteria.List<User>();
Related
I am current having an issue with getting records from database using nhibernate.
My 'publicstring' column is having two values, one with lower case and the other with upper case.
I am trying to fetch one of them depending on what is typed.
Below is my query
private string _publicId;
var _mediaFileShare = this.Session.QueryOver<MediaFileShare>()
.Where(q => q.Publicsting == _publicstring)
.SingleOrDefault();
Answers would be appreciated..
A naive solution is:
var _mediaFileShare = this.Session.QueryOver<MediaFileShare>()
.Where(q => q.PublicString == _publicString)
.List()
.SingleOrDefault(r => string.Compare(r.PublicString, _publicString, StringComparison.Ordinal) == 0);
If you're confident that the query will always return two rows then performance should be very acceptable. Alternatively you could use a dynamic order by, something like:
var query = this.Session.QueryOver<MediaFileShare>()
.Where(q => q.PublicString == _publicString);
query = _publicString == _publicString.ToLower()
? query.OrderBy(q => q.PublicString)
: query.OrderByDescending(q => q.PublicString);
var _mediaFileShare = query.Take(1).SingleOrDefault();
The results using an order by will be dependent on your database and its collation setting.
I am having issues getting Nhibernate 3.3.2.4000 to generate the correct subquery used in the orderby clause as displayed below:
select *
from dbo.Person p inner join dbo.Task t on p.Task_FK = p.TaskId
order by (select p.CustomerNumber where p.IsMain=1) desc
We have two entities: Task and Person
One task can have N persons related to it. I.e Task has an IList property.
How can I make Nhibernate generate the correct subquery ? I have gotten as far as something like this with the Query API:
query = query.OrderBy(x => x.Persons.Single(t => t.CustomerNumber));
but I am unsure how I can correctly generate the where clause as displayed in the original sql query. Is this perhaps easier done using the queryover api somehow?
Any advice or guidance is most welcome.
Task task = null
Person person = null;
var subquery = QueryOver.Of<Task>()
.Where(t => t.Id == task.Id)
.JoinQueryOver(t => t.Persons, () => person)
.Where(p => p.IsMain)
.Select(() => person.CustomerNumber);
var query = session.QueryOver(() => task)
.OrderBy(Projections.SubQuery(subquery))
.FetchMany(x => x.Persons)
return query.List();
I am trying to use query over to retrieve a collection of entities based upon a join/subquery as per the example below:
var types = new List<ActivityType>{ActivityType.CommentMedia, ActivityType.KeepMedia};
return _sessionFactory.GetCurrentSession()
.QueryOver<Activity>()
.Where(a.Type.IsIn(types))
.WithSubquery.WhereExists(QueryOver.Of<Resource>()
.Where(k => k.MemberKey == userId)
.Where(k => k.ResourceKey == activity.ResourceId)
)
.Take(take)
.List();
In other words retrieve all activities which are in the resource table matching the user and resource id.
I would do this in raw sql by either joining to Resource, or a subquery:
where a.ResourceId in (select resourceKey from resource where resource.memberkey = a.MemberId)
Not sure how to proceed in nhibernate though. Any suggestions?
(We don't want to use a mapping, as we want to keep the Activity entity very simple for performance reasons)
Thanks in advance
Activity activity = null;
return _sessionFactory.GetCurrentSession()
.QueryOver(() => activity)
.Where(a.Type.IsIn(types))
.WithSubquery.WhereProperty(a => a.ResourceId).In(QueryOver.Of<Resource>()
.Where(k => k.MemberKey == userId)
.Where(k => k.ResourceKey == activity.ResourceId)
)
.Take(take)
.List();
I am trying to select a distinct list of values from a table whilst ordering on another column.
The only thing working for me so far uses magic strings and an object array. Any better (type-safe) way?
var projectionList = Projections.ProjectionList();
projectionList.Add(Projections.Property("FolderName"));
projectionList.Add(Projections.Property("FolderOrder"));
var list = Session.QueryOver<T>()
.Where(d => d.Company.Id == SharePointContextHelper.Current.CurrentCompanyId)
.OrderBy(t => t.FolderOrder).Asc
.Select(Projections.Distinct(projectionList))
.List<object[]>()
.ToList();
return list.Select(l => new Folder((string)l[0])).ToList();
btw, doing it with linq won't work, you must select FolderOrder otherwise you'll get a sql error (ORDER BY items must appear in the select list if SELECT DISTINCT is specified.
)
and then doing that gives a known error : Expression type 'NhDistinctExpression' is not supported by this SelectClauseVisitor. regarding using anonymous types with distinct
var q = Session.Query<T>()
.Where(d => d.Company.Id == SharePointContextHelper.Current.CurrentCompanyId)
.OrderBy(d => d.FolderOrder)
.Select(d => new {d.FolderName, d.FolderOrder})
.Distinct();
return q.ToList().Select(f => new Folder(f));
All seems a lot of hoops and complexity to do some sql basics....
To resolve the type-safety issue, the syntax is:
var projectionList = Projections.ProjectionList();
projectionList.Add(Projections.Property<T>(d => d.FolderName));
projectionList.Add(Projections.Property<T>(d => d.FolderOrder));
the object [] thing is unavoidable, unless you define a special class / struct to hold just FolderName and FolderOrder.
see this great introduction to QueryOver for type-saftey, which is most certainly supported.
best of luck.
Querying child collections has been a recurring issue in our applications where we use NHibernate (via LINQ). I want to figure out how to do it right. I just tried forever to get this query to work efficiently using LINQ, and gave up. Can someone help me understand the best way to do something like this?
Model: ServiceProvider
HasMany->ServicesProvided
The gotcha here is that the HasMany is mapped as a component, so I can't directly query the ServicesProvided. For posterity's sake, here's the mapping:
public ServiceProviderMap()
{
DiscriminatorValue(ProfileType.SERVICE_PROVIDER.ID);
HasMany(p => p.ServicesProvided)
.Table("ServiceProvider_ServicesProvided")
.KeyColumn("ProfileID")
.Component(spMapping =>
{
spMapping.Map(service => service.ID)
.Not.Nullable();
})
.AsBag();
}
The query I am trying to create would return a collection of the count of each service that is provided. IE: Service1 -> 200, Service2 -> 465, etc.
I was able to get the query working using HQL, so here it is. Note that it just returns the ID of the service that is provided:
select service.ID, count(service)
from ServiceProvider as profile
inner join profile.ServicesProvided as service
group by service.ID
I was able to get the query "working" using LINQ, but it performed atrociously. Here's the code I used (warning - it's ugly).
Func<ServiceProvider, IEnumerable<ServicesProvided>> childSelector = sp => sp.ServicesProvided;
var counts = this._sessionManager.GetCurrentSession().Linq<ServiceProvider>()
.Expand("ServicesProvided")
.SelectMany(childSelector, (t, c) => new { t = t, c = c })
.Select(child => child.c)
.GroupBy(sp => sp.ID)
.Select(el => new { serviceID = el.Key, count = el.Count() });
I would love to learn how to do this correctly, please.
Short of going with HQL, the most elegant solution I can think of would be using a Criteria object. The following will give you what you need and with very low overhead:
ICriteria criteria = this._sessionManager.GetCurrentSession().CreateCriteria(typeof(ServiceProvider), "sp");
//set projections for the field and aggregate, making sure to group by the appropriate value
criteria.CreateAlias("sp.ServicesProvided", "s", JoinType.LeftOuterJoin)
.SetProjection(Projections.ProjectionList()
.Add(Projections.Property("s.ID"), "serviceID")
.Add(Projections.Count("sp.ID"), "count")
.Add(Projections.GroupProperty("s.ID")));
IList<object[]> results = criteria.List();
foreach (object[] entry in results)
{
int id = (int)entry[0], qty = (int)entry[1];
//Do stuff with the values
}