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Convert Sql to linq with groupby

I have view on which I use this request
Select Spendband, SUM(SpendCurrencyJob), SUM(SpendDocumentCount)
From analysis.vwJobSupplierMetrics
Where JobId = '500E0DD1-E3D3-4887-95EF-01D3C9EA8FD0'
Group by SpendBand
And it's running sucessfully
and get me this data
How I need to write it using linq to get same data?
I tried like this
var data = await _dbContext.VwJobSupplierMetrics.Where(x => x.JobId == jobId)
.GroupBy(x => x.SpendBand)
.Select(x => new HumpChartDto() {SpendBand = x.SpendBand}).ToListAsync();
But on new HumpChartDto() {SpendBand = x.SpendBand} I got Cannot resolve symbol 'SpendBand
How I can solve this?

First, after grouping on SpendBand, you need to access it via Key property. Second, to compute Sum, you can use Sum method.
var data = await _dbContext.VwJobSupplierMetrics.Where(x => x.JobId == jobId)
.GroupBy(x => x.SpendBand)
.Select(x => new HumpChartDto()
{
SpendBand = x.Key,
SumOfSpendCurrencyJob = x.Sum(s => s.SpendCurrencyJob),
SumOfSpendDocumentCount= x.Sum(s => s.SpendDocumentCount),
})
.ToListAsync();
Note - change the property name accordingly for name I've used for SumOfSpendCurrencyJob and SumOfSpendDocumentCount as don't know the definition of HumpChartDto class.

How can I reuse a subquery inside a select expression?

In my database I have two tables Organizations and OrganizationMembers, with a 1:N relationship.
I want to express a query that returns each organization with the first and last name of the first organization owner.
My current select expression works, but it's neither efficient nor does it look right to me, since every subquery gets defined multiple times.
await dbContext.Organizations
.AsNoTracking()
.Select(x =>
{
return new OrganizationListItem
{
Id = x.Id,
Name = x.Name,
OwnerFirstName = (x.Members.OrderBy(member => member.CreatedAt).First(member => member.Role == RoleType.Owner)).FirstName,
OwnerLastName = (x.Members.OrderBy(member => member.CreatedAt).First(member => member.Role == RoleType.Owner)).LastName,
OwnerEmailAddress = (x.Members.OrderBy(member => member.CreatedAt).First(member => member.Role == RoleType.Owner)).EmailAddress
};
})
.ToArrayAsync();
Is it somehow possible to summarize or reuse the subqueries, so I don't need to define them multiple times?
Note that I've already tried storing the subquery result in a variable. This doesn't work, because it requires converting the expression into a statement body, which results in a compiler error.

The subquery can be reused by introducing intermediate projection (Select), which is the equivalent of let operator in the query syntax.
For instance:
dbContext.Organizations.AsNoTracking()
// intermediate projection
.Select(x => new
{
Organization = x,
Owner = x.Members
.Where(member => member.Role == RoleType.Owner)
.OrderBy(member => member.CreatedAt)
.FirstOrDefault()
})
// final projection
.Select(x => new OrganizationListItem
{
Id = x.Organization.Id,
Name = x.Organization.Name,
OwnerFirstName = Owner.FirstName,
OwnerLastName = Owner.LastName,
OwnerEmailAddress = Owner.EmailAddress
})
Note that in pre EF Core 3.0 you have to use FirstOrDefault instead of First if you want to avoid client evaluation.
Also this does not make the generated SQL query better/faster - it still contains separate inline subquery for each property included in the final select. Hence will improve readability, but not the efficiency.
That's why it's usually better to project nested object into unflattened DTO property, i.e. instead of OwnerFirstName, OwnerLastName, OwnerEmailAddress have a class with properties FirstName, LastName, EmailAddress and property let say Owner of that type in OrganizationListItem (similar to entity with reference navigation property). This way you will be able to use something like
dbContext.Organizations.AsNoTracking()
.Select(x => new
{
Id = x.Organization.Id,
Name = x.Organization.Name,
Owner = x.Members
.Where(member => member.Role == RoleType.Owner)
.OrderBy(member => member.CreatedAt)
.Select(member => new OwnerInfo // the new class
{
FirstName = member.FirstName,
LastName = member.LastName,
EmailAddress = member.EmailAddress
})
.FirstOrDefault()
})
Unfortunately in pre 3.0 versions EF Core will generate N + 1 SQL queries for this LINQ query, but in 3.0+ it will generate a single and quite efficient SQL query.

How about this:
await dbContext.Organizations
.AsNoTracking()
.Select(x =>
{
var firstMember = x.Members.OrderBy(member => member.CreatedAt).First(member => member.Role == RoleType.Owner);
return new OrganizationListItem
{
Id = x.Id,
Name = x.Name,
OwnerFirstName = firstMember.FirstName,
OwnerLastName = firstMember.LastName,
OwnerEmailAddress = firstMember.EmailAddress
};
})
.ToArrayAsync();

How about doing this like
await dbContext.Organizations
.AsNoTracking()
.Select(x => new OrganizationListItem
{
Id = x.Id,
Name = x.Name,
OwnerFirstName = x.Members.FirstOrDefault(member => member.Role == RoleType.Owner).FirstName,
OwnerLastName = x.Members.FirstOrDefault(member => member.Role == RoleType.Owner)).LastName,
OwnerEmailAddress = x.Members.FirstOrDefault(member => member.Role == RoleType.Owner)).EmailAddress
})
.ToArrayAsync();

Retain default order for Linq Contains

I want to retain the default order that comes from sql, after processing by Linq also.I know this question has been asked before. Here is a link Linq Where Contains ... Keep default order.
But still i couldn't apply it to my linq query correctly. could anyone pls help me with this? Thanks!
Here is the query
var x = db.ItemTemplates.Where(a => a.MainGroupId == mnId)
.Where(a => a.SubGruopId == sbId)
.FirstOrDefault();
var ids = new List<int> { x.Atribute1, x.Atribute2, x.Atribute3, x.Atribute4 };
var y = db.Atributes.Where(a => ids.Contains(a.AtributeId))
.Select(g => new
{
Name = g.AtributeName,
AtType = g.AtributeType,
Options = g.atributeDetails
.Where(w=>w.AtributeDetailId!=null)
.Select(z => new
{
Value=z.AtributeDetailId,
Text=z.AtDetailVal
})
});

Your assumption is wrong. SQL server is the one that is sending the results back in the order you are getting them. However, you can fix that:
var x = db.ItemTemplates.Where(a => a.MainGroupId == mnId)
.Where(a => a.SubGruopId == sbId)
.FirstOrDefault();
var ids = new List<int> { x.Atribute1, x.Atribute2, x.Atribute3, x.Atribute4 };
var y = db.Atributes.Where(a => ids.Contains(a.AtributeId))
.Select(g => new
{
Id = g.AtributeId,
Name = g.AtributeName,
AtType = g.AtributeType,
Options = g.atributeDetails
.Where(w=>w.AtributeDetailId!=null)
.Select(z => new
{
Value=z.AtributeDetailId,
Text=z.AtDetailVal
})
})
.ToList()
.OrderBy(z=>ids.IndexOf(z.Id));
Feel free to do another select after the orderby to create a new anonymous object without the Id if you absolutely need it to not contain the id.
PS. You might want to correct the spelling of Attribute, and you should be consistent in if you are going to prefix your property names, and how you do so. Your table prefixes everything with Atribute(sp?), and then when you go and cast into your anonymous object, you remove the prefix on all the properties except AtributeType, which you prefix with At. Pick one and stick with it, choose AtName, AtType, AtOptions or Name, Type, Options.

Accessing Included object

im working with a new ASP.NET MVC3 project and it seems like im missing something in my LINQ skills.
Im formatting data for a Json "call" to be used my a jqGrid.
It works fine but now i want to add a related object by a Linq .Include() expression.
Think i better show with code.
var query = db.Products.Include("Category");
var jsonData = new
{
total = 1, // calc
page = page,
records = db.Products.Count(),
rows = query.Select(x => new { x.Id, x.Name, x.PartNr })
.ToList()
.Select(x => new {
id = x.Id,
cell = new string[] {
x.Id.ToString(),
x.Name.ToString(),
x.PartNr.ToString(),
//x.Category.Name.ToString()
//This does not work but object is there.
}}).ToArray(),
};
return Json(jsonData, JsonRequestBehavior.AllowGet);
Problem area => //x.Category.Name.ToString()
The strange thing here is if i Break and watch the query (//x.Category.Name.ToString()) i can actually find the attached Category object but how, if possible, can i use it in my ano method?

The problem is that you are first selecting an anonymous object with the properties Id, Name and PartNr. Then you execute this query against the database (with ToList()) and then you do a new select on the list of anonymous objects and try to access a property that's not in your anonymous object.
You should include the category in your anonymous object so you can access it in the second select. Or you should select the final structure with the first select query so it will be executed against your database.
This would work for example:
rows = query.Select(x => new { x.Id, x.Name, x.PartNr, x.Category })
.ToList()
.Select(x => new
{
id = x.Id,
cell = new string[] {
x.Id.ToString(),
x.Name.ToString(),
x.PartNr.ToString(),
x.Category.Name.ToString()
}
}).ToArray()
Or you simplify your query to only one and execute against the database:
rows = query.Select(x => new
{
x.Id,
cell = new string[]
{
x.Id.ToString(),
x.Name.ToString(),
x.PartNr.ToString(),
x.Category.Name.ToString()
}
}).ToArray()

Is it possible to use Select(l=> new{}) with SelectMany in EntityFramework

I am trying something that i not really sure but i want to ask here if it s possible.
Is it able to be done ?
public IQueryable<Info> GetInfo(int count, byte languageId)
{
return db.Info.SelectMany(i => i.LanguageInfo)
.Where(l => l.Language.id == languageId)
.Select(l => new Info { AddDate = l.Info.AddDate,
Description = l.Description,
EntityKey = l.Info.EntityKey,
id = l.Info.id,
Title = l.Title,
ViewCount = l.Info.ViewCount }
)
.OrderByDescending(i => i.id)
.Take(count);
}
When this method is executed i got an error
The entity or complex type
'GuideModel.Info' cannot be
constructed in a LINQ to Entities
query.
Does it mean "not possible" ?
Thank you

The error essentially indicates that the Entity Framework doesn't know how to create an Info object, since it is not bound to a table object. (Put another way, the Select call on the IQueryable cannot be translated into equivalent SQL.) You could perform the Select projection on the client via:
public IQueryable<Info> GetInfo(int count, byte languageId)
{
return db.Info.SelectMany(i => i.LanguageInfo)
.Where(l => l.Language.id == languageId)
.Take(count)
.AsEnumerable()
.Select(l => new Info { AddDate = l.Info.AddDate,
Description = l.Description,
EntityKey = l.Info.EntityKey,
id = l.Info.id,
Title = l.Title,
ViewCount = l.Info.ViewCount }
)
.OrderByDescending(i => i.id);
}

It is possible to use Select(l => new ...), but not with an Entity type. You need to use an anonymous type or a POCO type with a parameterless constructor. Entity types are "special" because of the way they interact with the ObjectContext. You can select them, but not new them up in a query.

The code below worked for me. Here "SearchTerm" is a complex type. Thanks Jason :)
var lstSynonym = TechContext.TermSynonyms
.Where(p => p.Name.StartsWith(startLetter))
.AsEnumerable()
.Select(u => new SearchTerm
{
ContentId = u.ContentId,
Title = u.Name,
Url = u.Url
});