Could anyone please help with the linq for this problem.
Users have a list of Properties and Properties have a list of Users.
I first do a query to get all Properties with a particular CompanyId. This makes a new list which we'll call MyProperties.
I need to get all Tenants that have a property in the MyProperties list.
For other reasons, I don't have access to the "PropertiesUsers" Join table.
Sorry if it looks like I haven't thought this through, I've been banging my head all day on it.
You can use Enumerable.SelectMany() to flatten the hierarchy:
var myProperties = dbContext.Properties.Where(property => property.CompanyId = companyId);
var tenants = myProperties.SelectMany(property => property.Tenants);
Use Intersect:
var myPropertyIds = MyProperties.Select(p => p.PropertyId).ToArray();
var result = Users.Where(u => myPropertyIds.Intersect(
u.Properties.Select(p => p.PropertyId))
.Any());
If you are sure that the properties in both lists are the same instances you could use
var result = Users.Where(u => MyProperties.Intersect(
u.Properties)
.Any());
Related
I'm trying to optimize an NHibernate query:
var profile = dc.Profiles.FirstOrDefault(p => p.IdProfile == idProfile);
I would like it to load a collection of Rights. I did this:
var profile = dc.Profiles.Fetch(x => x.Rights).FirstOrDefault(p => p.IdProfile == idProfile);
The results were totally different from what I expected - instead of getting single Profile with rights I got single profile with single right!
How can I fix it?
You can use like this
var profile = dc.Profiles.Where(p => p.IdProfile == idProfile).Select(x => x.Rights);
I have 2 entities, linked via a Many to Many called Parent and Child.
In Child I have an IList of Parents,
In Parent I have an IList of Childs.
I am trying to do a query on a list of parents, that is linked to a child.
Conceptually wise, I am looking for something like this:
var Query = session.QueryOver<Parent>()
Query.Where(o => o.Children.Contains(child));
But this won't work, so what ways can I get this to work?
Thanks!
You need to use JoinQueryOver
session.QueryOver<Parent>().JoinQueryOver<Child>(p => p.Childs)
.Where(c => c.Id == child.Id)
var query = session.QueryOver<Parent>()
.Where(o => o.Children.Contains(child));
or
var query = session.Query<Parent>()
.Where(o => o.Children.Contains(child));
or see Vadim
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.
Is it possible to use a multiquery and have two hql queries returning two different sets of entities where one of the sets are used in the other and that the session "fixes" this via the first level cache?
E.g. scenario (a dumb one and it could be solved with joins)
public class Room
{
...
public virtual ISet<Bookings> Bookings {get;set;}
public virtual bool IsAvailible {get;set;}
...
}
public class Booking
{
...
}
After executing a multicriteria with two hql's:
returning all rooms where
IsAvailible = true
returning all bookings having a room that has a room that IsAvailible
when accessing a room from the result and its bookings I want them to be resolved from the second resultset via the firstlevel cache of the session and there by avoiding n+1.
Generally speaking, NHibernate can use the cache to "combine" the results from queries executed through Multiquery. However, it should be noted that this usually only applies to cases where lazy collections are loaded with no restrictions whatsoever.
Examples:
Invoice iAlias = null;
InvoiceDetails idAlias = null;
// Base-Query: get Invoices with certain condition
var invoices = session.QueryOver<Invoice>()
.Where(i => i.Number == "001")
.Future<Invoice>();
// Option 1: this will still cause N+1 if we iterate through invoices,
// because it doesn't know better
var invoicedetails = session.QueryOver<InvoiceDetails>()
.JoinAlias(a => a.Invoice, () => iAlias)
.Where(() => iAlias.Number == "001")
.Future<InvoiceDetails>();
// Option 2: this will still cause N+1 if we iterate through invoices,
// because we limited the possible results using a where-condition
var invoices2 = session.QueryOver<Invoice>()
.Left.JoinAlias(i => i.Details, () => idAlias)
.Where(i => i.Number == "001")
.And(() => idAlias.Quantity > 5)
.Future<Invoice>();
// Option 3: this will work without N+1, because we don't use a filter
// -> NHibernate will use the collection in cache
var invoices3 = session.QueryOver<Invoice>()
.Left.JoinAlias(i => i.Details, () => idAlias)
.Where(i => i.Number == "001")
.Future<Invoice>();
foreach (Invoice i in invoices)
{
int count = i.Details.Count;
}
If we comment out two of the three options and execute the code, we will see that only option 3 will prevent a N+1, the other two will still load the InvoiceDetails for each Invoice in the loop.
Of course this is a very simple example and it is obvious that Option 3 could also be executed without the Base-query and still return the same result, but I hope you get the idea.
In the case where we load two different sets of entities, i.e. the root class is different as in Option 1, this "combining" will most likely not work.
Sorry, if I used QueryOver instead of HQL, but the same rules apply.
Gyus, keep in mind that sometimes you can have similar problems because of
LeftOuterJoin is not set.
.JoinAlias(x => x.Prop, () => propAlias, JoinType.LeftOuterJoin)
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
}