I want to simplify a linq Query that contains multiple includes.
My model is simple: a site is linked to one contract, that is linked to one client. On that client I need to get with a single request the telephones, mails and honorifics (appelRef).
I want a single request because behind the request is translated by entity framework into a SQL Server request.
Here is the linq request:
var search =
from IMT.Site s in imtContext.IMTObjects.OfType<IMT.Site>()
.Include(
s => s.LienContratSiteRef
.Select(l => l.Contrat)
.Select(c => c.LienContratClientRef
.Select(l => l.Client)
.Select(cl => cl.Telephones ) ) )
.Include(s => s.LienContratSiteRef
.Select(l => l.Contrat)
.Select(c => c.LienContratClientRef
.Select(l => l.Client)
.Select(cl => cl.Mails ) ) )
.Include(s => s.LienContratSiteRef
.Select(l => l.Contrat)
.Select(c => c.LienContratClientRef
.Select(l => l.Client)
.Select(cl => cl.AppelRef ) ) )
where s.Reference.ToString() == siteId
select s;
Yor can notice the block
.Include(
s => s.LienContratSiteRef
.Select(l => l.Contrat)
.Select(c => c.LienContratClientRef
.Select(l => l.Client)
..is repeated three time. Is ther a way to factorize that code block ?
Update: there are intermedray objects LienContratSiteRef and LienContratClientRef and relationships are 0 - *, so that LienContratSiteRef.Contrat and LienContratClientRef.Client are collections.
I also tried:
.Include(
s => s.LienContratSiteRef
.Select(l => l.Contrat)
.Select(c => c.LienContratClientRef
.Select(l => l.Client)
.Select(cl => new { Tels = cl.Telephones, Mail = cl.Mails, Appel = cl.AppelRef} ) ) )
but It results with a runtime error:
The Include path expression must refer to a navigation property
defined on the type.
The s => ... inside the include could be refactored into a delegate, then just .Include that delegate multiple times.
It looks like the signature would be Func<Site, IEnumerable<Client>>?
E.g.
static IEnumerable<Client> Foo(Site site) => site.LienContratSiteRef
.Select(l => l.Contrat)
.Select(c => c.LienContratClientRef
.Select(l => l.Client)
String-based Chaining
The Include() method supports a dot-delimited string parameter which can be used to pull an complete graph of objects down as opposed to making multiple chained select calls:
.Include("LienContratSiteRif.Contrat.LienContratClientRef.Client")
From there, if you wanted to include multiple additional properties, I believe that you could have another include for those sub properties:
.Include("LienContratSiteRif.Contrat.LienContratClientRef.Client, Client.Telephones, ...")
Lambda-based Chaining
You should be able to accomplish something similar by chaining your lambda-based includes into a single Include() call as well using:
.Include(c => LienContratSiteRif.Contrat.LienContratClientRef.Client)
It looks like you're trying to make an entity framework projection!
A project allows you to select only the properties that you want to return. (just like a SQL Select)
To use a projection, your code should roughly look like this:
var search = imtContext.IMTObjects.OfType<IMT.Site>()
.Where(s => s.Reference.ToString() == siteId)
.Select(s => new {
Telephones = s.LienContratSiteRef.Contrat.Select(c => c.LienContratClientRef.Client.Select(cli => cli.Telephones),
Mails = s.LienContratSiteRef.Contrat.Select(c => c.LienContratClientRef.Client.Select(cli => cli.Mails),
AppelRef = s.LienContratSiteRef.Contrat.Select(c => c.LienContratClientRef.Client.Select(cli => cli.AppelRef)
}).ToList();
If Telephones, Mails, AppelRefare also collections, then you can do aggregate the collections together like this in memory after the query has been run:
var telephones = search.SelectMany(x => x.Telephones).ToList();
var mails = search.SelectMany(x => x.Mails).ToList();
var appelRefs = search.SelectMany(x => x.AppelRef).ToList();
Related
I have added the following snippet in a nest query which returns a ISearchResponse<T>
.Query(query => query.Match(m =>
m.Field(f =>
f => !string.IsNullOrEmpty(f.Purchase.NationalCode.Trim()))
)))
But it makes no difference to the amount of records returned (and I know there are nulls in there)
Should I do be building my query some other way?
Edited to add:
I've tried the following based on this answer here but no luck either
.Query(query => query.Bool(b=>
b.Must(m=> m.Exists(
f=>f.Field("nationalCode")))))
.Query(query => query.Bool(b=>
b.MustNot(m=> m.Term(
"nationalCode", ""))))
Try the following
.Query(query => query
.Bool(b => b
.Must(m => m
.Exists(f => f.Field("nationalCode"))
)
.MustNot(m => m
.Term("nationalCode", "")
)
)
)
Both the .Must and .MustNot need to be called on the same bool query descriptor
I'm trying to improve the performance of a query that uses linq and fluent API.
The query looks like this:
var result = DbContext.Set<Parent>()
.Join(DbContext.Set<Child>(),
(parent) => parent.Id,
(child) => child.ParentId,
(parent, child) => cild)
.Select(x => new { x.SomeOtherId, x.AnotherId })
.Where(x => !filters.Contains(x.SomeOtherId))
.Select(x => x.AnotherId )
.Distinct()
.ToListAsync(cancellationToken);
As I understand, .Contains degrades the performance of queries such as this and using a Join is better, e.g
.Join(filters, (c) => c.SomeOtherId, (filterId) => filterId, (c, filterId) => c.AnotherId);
This will give results where there is a match, however how would I find results where there is not a match?
Thanks
I am working with QueryOver in NHibernate and I want to customize one property of my projected DTO using the following syntax:
IEnumerable<PersonResponseMessage> persons =
session.QueryOver<PersonEntity>()
.SelectList(list => list
.Select(p => p.Active).WithAlias(() => dto.Active)
.Select(p => p.Alert).WithAlias(() => dto.Alert)
.Select(p => p.Comments).WithAlias(() => dto.Comments)
.Select(p => string.Format("{0}api/Person/{1}", uriHelper.Root, p.Id)).WithAlias(() => dto.DetailsUrl)
)
.TransformUsing(Transformers.AliasToBean<PersonResponseMessage>())
.List<PersonResponseMessage>();
Unfortunately NHibernate cannot do this and throws an exception saying that:
Variable P referenced from scope "" is not defined
There are in common two ways. Partially we can move that concat operation on the DB side, as documented here:
16.7. Projection Functions
In this case, we'll use the Projections.Concat:
.SelectList(list => list
.Select(p => p.Active).WithAlias(() => dto.Active)
.Select(p => p.Alert).WithAlias(() => dto.Alert)
.Select(p => p.Comments).WithAlias(() => dto.Comments)
// instead of this
//.Select(p => string.Format("{0}api/Person/{1}", uriHelper.Root, p.Id))
// .WithAlias(() => dto.DetailsUrl)
// use this
.Select(p => Projections.Concat(uriHelper.Root, Projections.Concat, p.Id))
.WithAlias(() => dto.DetailsUrl)
)
.TransformUsing(Transformers.AliasToBean<PersonResponseMessage>())
.List<PersonResponseMessage>();
But I would vote for ex-post processing on the Application tier, in C#:
.SelectList(list => list
.Select(p => p.Active).WithAlias(() => dto.Active)
.Select(p => p.Alert).WithAlias(() => dto.Alert)
.Select(p => p.Comments).WithAlias(() => dto.Comments)
// just the ID
.Select(p => p.Id).WithAlias(() => dto.Id)
)
.TransformUsing(Transformers.AliasToBean<PersonResponseMessage>())
.List<PersonResponseMessage>()
// do the concat here, once the data are transformed and in memory
.Select(result =>
{
result.DetailsUrl = string.Format("{0}api/Person/{1}", uriHelper.Root, p.Id)
return result;
});
I am trying to do a query like:
var a = session.QueryOver<Site>()
.SelectList(
x => x.Select(p => p.SiteName)
.Select(p => p.SiteId).Select(p => p.RegionLocation.City))
.List<object[]>();
but I get the error
could not resolve property: RegionLocation.City of: Entities.Site
The property exists and I can retrieve it using LINQ but QueryOver does not work. What am I doing wrong ?
As far as i remember, with QueryOver, you have to join all entities in the association in order to be able to access it's properties.
This means you ought to do something like:
(notice the .JoinQueryOver)
var a = session.QueryOver<Site>()
.JoinQueryOver(s => s.RegionLocation)
.SelectList(
x => x.Select(p => p.SiteName)
.Select(p => p.SiteId)
.Select(p => p.RegionLocation.City))
.List<object[]>();
Or maybe this will work:
RegionLocation regionLocationAlias = null;
var a = session.QueryOver<Site>()
.JoinAlias(s => s.RegionLocation, () => regionLocationAlias)
.SelectList(
x => x.Select(p => p.SiteName)
.Select(p => p.SiteId)
.Select(() => regionLocationAlias.City))
.List<object[]>();
Also you might want to have a look at https://github.com/davybrion/NHibernateWorkshop/tree/master/NHibernateWorkshop
There's lots of great examples!
Specifically for your problem, have a look at: https://github.com/davybrion/NHibernateWorkshop/blob/master/NHibernateWorkshop/Querying/QueryOver/Projecting.cs
I know that this won't work as written, but I'm struggling to see the right answer, and this non-functional code hopefully illustrates what I'm trying to achieve:
var defaults = _cilQueryContext.DefaultCharges
.Where(dc => dc.ChargingSchedule_RowId == cs.RowId);
List<DevelopmentType> devTypes =
defaults.Select(dc => dc.DevelopmentType)
.Include(d => d.DefaultCharges)
.Include(d => d.OverrideCharges.Where(oc => oc.ChargingSchedule_RowId == cs.RowId))
.Include(d => d.OverrideCharges.Select(o => o.Zone))
.ToList();
Essentially, I had presumed this required a join, but seeing as I'm trying to select a parent object containing two related types of children, I can't see what would go in the join's "select new" clause.
As far as I am aware Include does not support this type of sub-querying. Your best option is to use projection e.g.
List<DevelopmentType> devTypes =
defaults.Include(x => x.DefaultCharges)
.Include(x => x.OverrideCharges)
.Select(x => new {
DevType = x.DevelopmentType,
Zones = x.OverrideCharges.Where(oc => oc.ChargingSchedule_RowId == cs.RowId)
.Select(oc => oc.Zone).ToList()
})
.Select(x => x.DevType)
.ToList();