We Keep Coding

Linq - Order by in Include

I have a situation where OrderBy need to be done for Include object. This is how I have tried so far
Customers query = null;
try
{
query = _context.Customers
.Include(x => x.CustomerStatus)
.ThenInclude(x => x.StatusNavigation)
.Select(x => new Customers()
{
Id = x.Id,
Address = x.Address,
Contact = x.Contact,
Name = x.Name,
CustomerStatus = new List<CustomerStatus>
{
x.CustomerStatus.OrderByDescending(y => y.Date).FirstOrDefault()
}
})
.FirstOrDefault(x => x.Id == 3);
}
catch (Exception ex)
{
throw;
}
The above code successfully ordering the include element but it is not including it's child table.
Eg: Customer include CustomerStatus but CustomerStatus not including StatusNavigation tables.
I even tried with this but neither it can help me
_context.Customers
.Include(x => x.CustomerStatus.OrderByDescending(y => y.Date).FirstOrDefault())
.ThenInclude(x => x.StatusNavigation).FirstOrDefault(x => x.Id == 3);
What am I doing wrong please guide me someone
Even I tried this way
var query = _context.CustomerStatus
.GroupBy(x => x.CustomerId)
.Select(x => x.OrderByDescending(y => y.Date).FirstOrDefault())
.Include(x => x.StatusNavigation)
.Join(_context.Customers, first => first.CustomerId, second => second.Id, (first, second) => new Customers
{
Id = second.Id,
Name = second.Name,
Address = second.Address,
Contact = second.Contact,
CustomerStatus = new List<CustomerStatus> {
new CustomerStatus
{
Id = first.Id,
CustomerId = first.CustomerId,
Date = first.Date,
StatusNavigation = first.StatusNavigation
}
},
}).FirstOrDefault(x => x.Id == 3);
but this is hitting a databases a 3 times and filtering the result in memory.
First select all data from customer status and then from status and then from customer then it filter all the data in memory. Is there any other efficient way to do this??
This is how I have prepared by entity class

As #Chris Pratt mentioned once you are doing new Customer inside the select you are creating a new model. You are discarding the models build by the EntityFramework. My suggestion would be have the query just:
query = _context.Customers
.Include(x => x.CustomerStatus)
.ThenInclude(x => x.StatusNavigation);
Like this you would have an IQueryable object which it would not be executed unless you do a select from it:
var customer3 = query.FirstOrDefault(x=>x.Id==3)
Which returns the customer and the interlinked tables (CustomerStatus and StatusNavigation). Then you can create the object that you want:
var customer = new Customers()
{
Id = customer3.Id,
Address = customer3.Address,
Contact = customer3.Contact,
Name = x.Name,
CustomerStatus = new List<CustomerStatus>
{
customer3.CustomerStatus.OrderByDescending(y => y.Date).FirstOrDefault()
}
})
In this way you can reuse the query for creating different response objects and have a single querying to database, but downside is that more memory is used then the original query (even though it shouldn't be too much of an issue).
If the model that is originally return from database doesn't meet the requirements (i.e. you always need to do: CustomerStatus = new List {...} ) it might indicate that the database schema is not well defined to the needs of the application, so a refactoring might be needed.

What I think is happening is that you are actually overriding the Include and ThenInclude. Include is explicitly to eager-load a navigation property. However, you're doing a couple of things that are likely hindering this.
First, you're selecting into a new Customer. That alone may be enough to break the logic of Include. Second, you're overriding what gets put in the CustomerStatus collection. That should ideally be just loaded in automatically via Include, but by altering it to just have the first entity, you're essentially throwing away the effect of Include. (Selecting a relationship is enough to cause a join to be issued, without explicitly calling Include). Third, the ThenInclude is predicated on the Include, so overriding that is probably throwing out the ThenIncude as well.
All this is conjecture. I haven't done anything exactly like what you're doing here before, but nothing else makes sense.
Try selecting into a new CustomerStatus as well:
CustomerStatus = x.CustomerStatus.OrderByDescending(o => o.Date).Select(s => new CustomerStatus
{
x.Id,
x.Status,
x.Date,
x.CustomerId,
x.Customer,
x.StatusNavigation
})
You can remove the Include/ThenInclude at that point, because the act of selecting these relationships will cause the join.

After Reading from Couple of sources (Source 1) and (Source 2). I think what is happening is that If you use select after Include. It disregards Include even if you are using Include query data in select. So to solve this use .AsEnumerable() before calling select.
query = _context.Customers
.Include(x => x.CustomerStatus)
.ThenInclude(x => x.StatusNavigation)
.AsEnumerable()
.Select(x => new Customers()
{
Id = x.Id,
Address = x.Address,
Contact = x.Contact,
Name = x.Name,
CustomerStatus = new List<CustomerStatus>
{
x.CustomerStatus.OrderByDescending(y => y.Date).FirstOrDefault()
}
})
.FirstOrDefault(x => x.Id == 3);

Combine two condition from two table with OR clause in orchard HQL query

In orchard cms i want to write a query containing two condition over two different ContentPartRecord combined with OR clause. one possible way to combine conditions is :
var query = _contentManager.HqlQuery()
.Where(a => a.ContentPartRecord<ProductPartRecord>(), a => a.Eq("Title", "myTitle"))
.Where(a => a.ContentPartRecord<TitlePartRecord>(), a => a.Eq("Price", 1000))
.List();
but this one combines two condition with And clause. i think something like following along with some changes (which would be the answer for this question) could be the case:
var query = _contentManager.HqlQuery()
.Join(a => a.ContentPartRecord<ProductPartRecord>())
.Join(a => a.ContentPartRecord<TitlePartRecord>())
.Where(a => a.ContentItem(),
a => a.Or(p => p.Eq("ProductPartRecord.Price",
"1000"), t => t.Eq("TitlePartRecord.Title", "myTitle")))
.List();
but i couldn't get it working.any body have any suggestion?

When you use where clause in HqlQuery you need to pass Alias (as first parameter). Alias means that you will be apply where clause to specific table (class that represent this table). And when you use OR clause that you definitely need to compare columns of the specific table in two parts of OR clause (left and right from the OR clause). And i think this is not possible to do you need a standard way.
But you can use:
Action<IAliasFactory> productPartRecordAlias = x => x.ContentPartRecord<ProductPartRecord>().Named("productPartRecord");
Action<IAliasFactory> titlePartRecordAlias = x => x.ContentPartRecord<TitlePartRecord>().Named("titlePartRecord");
var query = _contentManager.HqlQuery()
.Join(productPartRecordAlias)
.Join(titlePartRecordAlias)
.Where(a => a.ContentItem(), p => p.Gt("Id", "0 AND (productPartRecord.Price = 1000 OR titlePartRecord.Title = 'myTitle')"));

Entity Framework include with a condition

I have two entities, which are related, ActiveContract and BudgetSource. I'm trying to grab all the BudgetSource which are marked as isActive = true, along with all associated ActiveContracts which are also marked isActive = true. I've tired:
var d = budgetSourceRep.All.Where(x => x.isAcitve)
.OrderBy(x => x.SourceName)
.Include(z => z.ActiveContracts.Where(q => q.isActive))
.Select(y => new EditSelectItemViewModel
{
Id = y.Id,
SourceName = y.SourceName,
DisplayOnNew = y.DisplayOnNew,
NumberOfTimesUsed = y.ActiveContracts.Count()
}).ToList();
but that gives me an error
The Include path expression must refer to a navigation property defined on the type. Use dotted paths for reference navigation properties and the Select operator for collection navigation properties. Parameter name: path
I then changed it to put the filter in the projection:
var d = budgetSourceRep.All.Where(x => x.isAcitve)
.OrderBy(x => x.SourceName)
.Include(z => z.ActiveContracts)
.Select(y => new EditSelectItemViewModel
{
Id = y.Id,
SourceName = y.SourceName,
DisplayOnNew = y.DisplayOnNew,
NumberOfTimesUsed = y.ActiveContracts.Count(a => a.isActive)
}).ToList();
that works, but I'm assuming it's going to make a second query to do that? If so, is there a way to do it in one shot.

that works, but i'm assuming it's going to make a second query to do that?
No, it is not. You can see for yourself by looking at the generated SQL for this query.
It is within the bounds of theoretical possibility for the query provider to have successfully translated your first query into SQL, but doing so is...hard. This simply isn't a feature that the developers of EF chose to put into their query provider. Instead you are forced to project out a collection of related entities in some way to filter them, you cannot use Include to do it for you.

Linq to Sql: Optimizing lamba expression - clean code

I have this expression, which generates single query to the database:
db = new MyDataContext();
var productInCity = db.Products
.Where(n => n.id == 2)
.Select(k => new ProductInCityDto()
{
ProductName = k.ProductName,
CityName = k.Store.City.Name,
CountryName = k.Store.City.Country.Name
.
.
.
})
.FirstOrDefault();
I want to make this code cleaner, by putting the mapping in a function, extension method or in the object's constructor, something like this:
db = new MyDataContext();
var productInCity = db.Products
.Where(n => n.id == 2)
.Select(k => new ProductInCityDto(k))
.FirstOrDefault();
But, in this case, multiple queries to the DB are generated (I use LinqToSql Profiler).
Is there a way to isolate the mapping (Select statement) in order to achieve better code readability?

YES, if you look at the actual signature of the Select extension method on IQueryable you will find that it does not take a function but an Expression>.
So, just do that...
Expression<Func<Product, ProductInCityDto>> MyMappingExpression
{
get
{
return product => new ProductInCityDto
{
...
}
}
}
and then
db = new MyDataContext();
var productInCity = db.Products.Where(n => n.id == 2)
.Select(MyMappingExpression)
.FirstOrDefault();
If you need to use MyMappingExpression in process you will likely want to convert it to a
Func<Product, ProductInCityDto>
by calling the Expression.Compile() method.

Instead of creating mappings by hand, you may use AutoMapper. But if you do not want to create the mapping using a third party tool just change the query to the following;
var productInCity = new ProductInCity(
db.Products.Include("Store").SingleOrDefault(n => n.id == 2));

Entity Framework How to fill NotMapped Property that need a join?

I have a PostInfo table and LikeInfo Table,PostInfo have list of LikeInfo (for post likes).PostInfo table have a NotMapped property named of "LikeCount".
I want select list of PostInfoes and join to LikeInfo table and calcualte count of LikeInfoes of post and fill count of this to LikeCount property.
Here is my sample:
var query = context.PostInfoes.Where(x => x.UserId == userId).Include(x => x.LikeInfoes);
foreach (var item in query)
{
item.LikeCount = item.LikeInfoes.Count;
}
return query.ToList();
That is not good way for me because I do foreach on query and set LikeCount manualy however I dont want/need include full peoperties of LikeInfo table in this case.
I'm finding the best and easy way to fill this property.

Since EF6 does not allow projecting to entity type, you need to use LINQ to Entities query with intermediate anonymous type projection containing all necessary data, then switch to LINQ to Objects (via AsEnumerable()) and do the final projection, using a delegate block to perform the necessary unmapped property fixups:
var result = context.PostInfoes
.Where(x => x.UserId == userId)
.Select(x => new { Info = x, LikeCount = x.LikeInfoes.Count() })
.AsEnumerable()
.Select(x =>
{
x.Info.LikeCount = x.LikeCount;
return x.Info;
})
.ToList();