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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();

EF Dynamic Field Select using LINQ

I have the following select:
var sortedCodes = Codes
.Where(c => c.Active)
.OrderByDescending(x => x.SortOrder)
.Select(b => new { b.Display, b.NumericCode, b.SortOrder })
.Distinct()
.ToList();
The table Code has many columns such as NumericCode, TextCode, AlphaCode, ThreeCode, FourCode, FiveCode. I am using this table to build selects in my UI. Is there a way I can create some dynamic code so I can pass in the column name to use for the value?
The above select would look like this:
.Select(b => new { b.Display, "TextCode", b.SortOrder })
I was thinking I could use an Expression, but I do not think this is exactly what I need as it is actually printing the lambda as the value.
var arg = Expression.Parameter(typeof(Code), "b");
var body = Expression.Property(arg, valueColumn);
var lambda = Expression.Lambda<Func<Code, string>>(body, arg);
var sortedCodes = Codes
.Where(c => c.Active)
.OrderByDescending(x => x.SortOrder)
.Select(b => new { b.Display, Value=lambda, b.SortOrder })
.Distinct()
.ToList();

Reference to junction table throws ArgumentNullException 'Value cannot be null'

I'm trying to get Ingredients through junction table for my Recipes.
_context.RecipeIngredients
.Include(rI => rI.Recipe)
.ThenInclude(r => r.RecipeIngredients)
.Where(rI => ingredients.Contains(rI.IngredientId))
.GroupBy(rI => rI.Recipe)
.Select(g => new
{
Recipe = g.Key,
MatchingIngredients = (double)g.Count() / (double)g.Key.RecipeIngredients.Count(),
g.Key.ComplexityTag,
g.Key.TypeTag,
g.Key.RecipeIngredients,
})
.OrderByDescending(r => r.MatchingIngredients)
.Take(MaxAmountBestRecipes)
.AsEnumerable()
.Select(a => new RecipeDTO()
{
Title = a.Recipe.Title,
Steps = a.Recipe.Steps,
ComplexityTag = a.ComplexityTag?.Complexity,
TypeTag = a.TypeTag?.Type,
IngredientAmount = a.RecipeIngredients?.ToDictionary(rI => rI.Ingredient.Name, rI => rI.Quantity),
})
.ToList();
I discovered it is caused by g.Key.RecipeIngredients, but I can't find any workaround, solution for this problem. I tried eagar loading(as you can see), and lazy loading, both didn't work. I hope there is solution in one query to db in linq. Moreover, will it work like in the above line, after update.:
IngredientAmount = a.RecipeIngredients?.ToDictionary(rI => rI.Ingredient.Name, rI => rI.Quantity)
EDIT
I have divied linq query and here you have after which statement ArgumentNullException is thrown:
var tmp = _context.RecipeIngredients
.Where(rI => ingredients.Contains(rI.IngredientId))
.GroupBy(rI => rI.Recipe)
.Select(g => new
{
Recipe = g.Key,
MatchingIngredients = (double)g.Count() / (double)g.Key.RecipeIngredients.Count(),
g.Key.ComplexityTag,
g.Key.TypeTag,
g.Key.RecipeIngredients
})
.ToList();

Include doesn't work when you change the shape of the query (e.g. when you're querying for RecipeIngredients but are projecting to another type).
The only place I'm thinking a NULL is a problem is the key selector when creating the dictionary. Since Include won't do anything for you, ri.Ingredient will always be NULL. Include the Ingredients in the original projection (and remove the Include since it's useless):
_context.RecipeIngredients
.Where( rI => ingredients.Contains( rI.IngredientId ) )
.GroupBy( rI => rI.Recipe )
.Select( g => new
{
Recipe = g.Key,
MatchingIngredientCount = (double)g.Count() / (double)g.Key.RecipeIngredients.Count(),
g.Key.ComplexityTag,
g.Key.TypeTag,
g.Key.RecipeIngredients,
// this eager-loads the `Ingredient` entities
// EF will automatically wire them up to the `RecipeIngredient` entities
// if tracking is enabled
Ingredients = g.Key.RecipeIngredients.Select( ri => ri.Ingredient ),
} )
.OrderByDescending(r => r.MatchingIngredients)
.Take(MaxAmountBestRecipes)
.ToArray()
.Select( a = new ...
{
...
IngredientAmount = a.RecipeIngredients.ToDictionary(
ri => ri.Ingredient.Name, // ri.Ingredient should now not be NULL
ri => ri.Quantity )
} );
Edit: if you don't need the entire RecipeIngredient or Recipe entities in your results, just project what you need in the orig name with the RecipeIngredients in the first projection:
IngredientNamesAndQuantity = g.Key.RecipeIngredients.Select( ri => new
{
ri.Quantity,
ri.Ingredient.Name,
}
Then use that projection to build your dictionary:
IngredientAmount = a.IngredientNamesAndQuantity.ToDictionary(
at => at.Name,
at => at.Quantity )

How to create query of queries using LINQ?

I'm trying to convert query of queries used in ColdFusion to LINQ and C#. The data come from data files, rather than from the database.
I converted the first query, but have no clue as to
how to use it to query the second query.
how to include count(PDate) as DayCount in the second query.
Below is the code using query of queries in ColdFusion:
First query
<cfquery name="qSorted" dbtype = "query">
SELECT OA, CD,PDate,
FROM dataQuery
GROUP BY CD,OA,PDate,
</cfquery>
Second query
<cfquery name="qDayCount" dbtype = "query">
SELECT OA, CD, count(PDate) as DayCount
FROM qSorted // qSorted is from the first query.
GROUP BY
OA, CD
ORDER BY
OA, CD
</cfquery>
Here's the first converted LINQ query, and it works fine:
var Rows = allData.SelectMany(u => u._rows.Select(t => new
{
OA = t[4],
CD = t[5],
PDate = t[0]
}))
.GroupBy(x => new { x.CD, x.OA, x.PDate })
.Select(g => new
{
g.Key.OA,
g.Key.CD,
g.Key.PDate
})
.ToList();
Here's the pseudo-code for the second LINQ query, which I need your assistance:
var RowsDayCount = Rows //Is this correct? If not, how to do it?
.GroupBy(x => new { x.OA, x.PDate, x.CD, })
.Select(g => new
{
g.Key.OA,
g.Key.CD,
g.Key.PDate,//PDate should be PDate.Distinct().Count() asDayCount
// See DayCount in cfquery name="qDayCount" above.
})
.OrderBy(u => u.OA)
.ThenBy(u => u.CD)
.ToList();

Your second query origionally wasn't grouping on PDate, but your translation is. That's wrong. If you want to count the number of PDates for each OA/CD pair, you need to not group on PDate. Once you've made that change, you can modify the Select to pull out all of the PDate values from the group, and count the distinct values.
.GroupBy(x => new { x.OA, x.CD, })
.Select(g => new
{
g.Key.OA,
g.Key.CD,
DayCount = g.Select(item => item.PDate).Distinct().Count(),
})