Develop Reference

EF get list of parent entities that have list of child

I have to next 2 entities in my project
public class Product
{
public Product()
{
this.ProductImages = new HashSet<ProductImage>();
this.ProductParams = new HashSet<ProductParam>();
}
public int ID { get; set; }
public int BrandID { get; set; }
public int CodeProductTypeID { get; set; }
public string SeriaNumber { get; set; }
public string ModelNumber { get; set; }
public decimal Price { get; set; }
public bool AvailableInStock { get; set; }
public virtual Brand Brand { get; set; }
public virtual CodeProductType CodeProductType { get; set; }
public virtual ICollection<ProductImage> ProductImages { get; set; }
public virtual ICollection<ProductParam> ProductParams { get; set; }
}
public class ProductParam
{
public int Id { get; set; }
public int ProductId { get; set; }
public int CodeProductParamId { get; set; }
public string Value { get; set; }
public virtual Product Product { get; set; }
public virtual CodeProductParam CodeProductParam { get; set; }
}
and I want to get list of Products which has list of specified parameters
var prodParamCritria = new List<ProductParam>()
{
new ProductParam(){CodeProductParamId =1, Value="Black" },
new ProductParam(){CodeProductParamId =2, Value="Steal"}
};
in sql I can do it by using EXISTS clause twise
SELECT *
FROM Products p
WHERE EXISTS (
SELECT *
FROM ProductParams pp
WHERE pp.ProductId = p.ID
AND (pp.CodeProductParamId = 1 AND pp.[Value] = N'Black')
)
AND EXISTS (
SELECT *
FROM ProductParams pp
WHERE pp.ProductId = p.ID
AND pp.CodeProductParamId = 2
AND pp.[Value] = N'Steal'
)
How can i get same result by EF methods or linq

Try this:
var products= db.Products.Where(p=>p.ProductParams.Any(pp=>pp.CodeProductParamId == 1 && pp.Value == "Black") &&
p.ProductParams.Any(pp=>pp.CodeProductParamId == 2 && pp.Value == "Steal"));
Update
The problem in work with that list of ProductParam to use it as a filter is that EF doesn't know how to translate a PodructParam object to SQL, that's way if you execute a query like this:
var products2 = db.Products.Where(p => prodParamCritria.All(pp => p.ProductParams.Any(e => pp.CodeProductParamId == e.CodeProductParamId && pp.Value == e.Value)));
You will get an NotSupportedException as you comment in the answer of #BostjanKodre.
I have a solution for you but probably you will not like it. To resolve that issue you could call the ToList method before call the Where. This way you will bring all products to memory and you would work with Linq to Object instead Linq to Entities, but this is extremely inefficient because you are filtering in memory and not in DB.
var products3 = db.Products.ToList().Where(p => prodParamCritria.All(pp => p.ProductParams.Any(e => pp.CodeProductParamId == e.CodeProductParamId && pp.Value == e.Value)));
If you want filter by one criteria then this could be more simple and you are going to be able filtering using a list of a particular primitive type. If you, for example, want to filter the products only by CodeProductParamId, then you could do this:
var ids = new List<int> {1, 2};
var products = db.Products.Where(p => ids.All(i=>p.ProductParams.Any(pp=>pp.CodeProductParamId==i))).ToList();
This is because you are working with a primitive type and not with a custom object.

I suppose something like that should work
db.Product.Where(x => x.ProductParams.FirstOrDefault(y => y.CodeProductParamId == 1) != null && x.ProductParams.FirstOrDefault(y => y.CodeProductParamId == 2) != null).ToList();
or better
db.Product.Where(x => x.ProductParams.Any(y => y.CodeProductParamId == 1) && x.ProductParams.Any(y => y.CodeProductParamId == 2)).ToList();
Ok, if you need to make query on parameters in list prodParamCriteria it will look like this:
db.Product.Where(x => prodParamCritria.All(c=> x.ProductParams.Any(p=>p.CodeProductParamId == c.CodeProductParamId && p.Value== c.Value))).ToList();
I forgot that complex types cannot be used in query database, so i propose you to convert your prodParamCriteria to dictionary and use it in query
Dictionary<int, string> dctParams = prodParamCritria.ToDictionary(x => x.CodeProductParamId , y=>y.Value);
db.Product.Where(x => dctParams.All(c => x.ProductParams.Any(p=> p.CodeProductParamId == c.Key && p.Value== c.Value))).ToList();

another variation:
IEnumerable<Int32> lis = prodParamCritria.Select(x => x.CodeProductParamId).ToList();
var q = Products.Select(
x => new {
p = x,
cs = x.ProductParams.Where(y => lis.Contains(y.Id))
}
).Where(y => y.cs.Count() == lis.Count()).
ToList();
with a named class like (or maybe without, but not in linqpad)
public class daoClass {
public Product p {get; set;}
public Int32 cs {get; set;}
}
IEnumerable<Int32> lis = prodParamCritria.Select(x => x.CodeProductParamId).ToList();
var q = Products.Select(
x => new daoClass {
p = x,
cs = x.ProductParams.Where(y => lis.Contains(y.Id))
}
).Where(y => y.cs.Count() == lis.Count()).
SelectMany(y => y.p).
ToList();

How to find value from a Dictionary<int, IEnumerable<Struct>>

I have a dictionary, salaryFitmentDictionary which I would like to query (linq or lambda) based on example: where employeedId = 1 and EarningDeductionId = 145 and get the value of the balance, EDBalance.
How would I achieve this?
var balance = salaryFitmentDictionary.Where...
Dictionary<int, IEnumerable<SalaryFitmentInfoMonth>> salaryFitmentDictionary = new Dictionary<int, IEnumerable<SalaryFitmentInfoMonth>>();
employeeIdList.ToList().ForEach(employeedId =>
{
var perEmployeeFitments = from pf in _db.PayFitments.AsEnumerable()
join ed in _db.EarningDeductions.AsEnumerable()
on pf.EarningDeductionId equals ed.EarningDeductionId
where pf.EmployeeId == employeedId
select new SalaryFitmentInfoMonth
{
EDId = pf.EarningDeductionId,
EDAmount = pf.Amount,
EDBalance = pf.Balance.GetValueOrDefault(),
EDType = ed.EDType,
IsTaxable = ed.IsTaxable,
IsBenefit = ed.IsBenefit,
IsLoan = ed.IsLoan,
IsAdvance = ed.IsAdvance,
Limit = ed.TaxIfMoreThan.GetValueOrDefault()
};
salaryFitmentDictionary.Add(employeedId, perEmployeeFitments);
});
public struct SalaryFitmentInfoMonth
{
public int EDId { get; set; }
public decimal EDAmount { get; set; }
public decimal? EDBalance { get; set; }
public EarnDeduct EDType { get; set; }
public bool IsTaxable { get; set; }
public bool IsBenefit { get; set; }
public bool IsLoan { get; set; }
public bool IsAdvance { get; set; }
public decimal? Limit { get; set; }
}

IEnumerable<SalaryFitmentInfoMonth> salaries = salaryFitmentDictionary[1];
SalaryFitmentInfoMonth salary = salaries.FirstOrDefault(s => s.EDId == 45);
You should handle the case that salaryFitmentDictionary doesn't contain one with this ID. So you could use TryGetValue instead. If no salary has this EDId FirstOrDefault returns null.
So here's the safer version:
IEnumerable<SalaryFitmentInfoMonth> salaries;
if(salaryFitmentDictionary.TryGetValue(1, out salaries))
{
SalaryFitmentInfoMonth salary = salaries.FirstOrDefault(s => s.EDId == 45);
if(salary != null)
{
// do something ...
}
}
If you expect more than one match you could use Enumerable.Where instead of FirstOrDefault.

You could use SelectMany method in LINQ method syntax:
Int32 id = 1;
Int32 edId = 147;
var result = salaryFitmentDictionary.
Where((pair) => pair.Key == id ).
SelectMany((pair) =>
pair.Value.Where((perEmployeeFitment) => perEmployeeFitment.EDId == edId)).
Select(perEmployeeFitment => perEmployeeFitment.EDBalance).
Single();
Or in query syntax:
Int32 id = 1;
Int32 edId = 147;
var result = (from pair in salaryFitmentDictionary
from perEmployeeFitment in pair.Value
where pair.Key == id
where perEmployeeFitment.EDId == edId
select perEmployeeFitment.EDBalance).Single();

Grouping and flattening list with linq and lambda

I have the following class
public class SolicitacaoConhecimentoTransporte
{
public long ID { get; set; }
public string CodigoOriginal { get; set; }
public DateTime Data { get; set; }
public List<CaixaConhecimentoTransporte> Caixas { get; set; }
}
I would like to know if there is a way of achiveing the same behavior of the code below using Linq (with lambda expression syntax),
List<SolicitacaoConhecimentoTransporte> auxList = new List<SolicitacaoConhecimentoTransporte>();
foreach (SolicitacaoConhecimentoTransporte s in listaSolicitacao)
{
SolicitacaoConhecimentoTransporte existing =
auxList.FirstOrDefault(f => f.CodigoOriginal == s.CodigoOriginal &&
f.Data == s.Data &&
f.ID == s.ID);
if (existing == null)
{
auxList.Add(s);
}
else
{
existing.Caixas.AddRange(s.Caixas);
}
}
return auxList;
In other words, group all entities that have equal properties and flat all lists into one.
Thanks in advance.

Use anonymous object to group by three properties. Then project each group to new SolicitacaoConhecimentoTransporte instance. Use Enumerable.SelectMany to get flattened sequence of CaixaConhecimentoTransporte from each group:
listaSolicitacao.GroupBy(s => new { s.CodigoOriginal, s.Data, s.ID })
.Select(g => new SolicitacaoConhecimentoTransporte {
ID = g.Key.ID,
Data = g.Key.Data,
CodigoOriginal = g.Key.CodigoOriginal,
Caixas = g.SelectMany(s => s.Caixas).ToList()
}).ToList()

Efficient way to call .Sum() on multiple properties

I have a function that uses LINQ to get data from the database and then I call that function in another function to sum all the individual properties using .Sum() on each individual property. I was wondering if there is an efficient way to sum all the properties at once rather than calling .Sum() on each individual property. I think the way I am doing as of right now, is very slow (although untested).
public OminitureStats GetAvgOmnitureData(int? fnsId, int dateRange)
{
IQueryable<OminitureStats> query = GetOmnitureDataAsQueryable(fnsId, dateRange);
int pageViews = query.Sum(q => q.PageViews);
int monthlyUniqueVisitors = query.Sum(q => q.MonthlyUniqueVisitors);
int visits = query.Sum(q => q.Visits);
double pagesPerVisit = (double)query.Sum(q => q.PagesPerVisit);
double bounceRate = (double)query.Sum(q => q.BounceRate);
return new OminitureStats(pageViews, monthlyUniqueVisitors, visits, bounceRate, pagesPerVisit);
}
private IQueryable<OminitureStats> GetOmnitureDataAsQueryable(int? fnsId, int dateRange)
{
var yesterday = DateTime.Today.AddDays(-1);
var nDays = yesterday.AddDays(-dateRange);
if (fnsId.HasValue)
{
IQueryable<OminitureStats> query = from o in lhDB.omniture_stats
where o.fns_id == fnsId
&& o.date <= yesterday
&& o.date > nDays
select new OminitureStats (
o.page_views.GetValueOrDefault(),
o.monthly_unique.GetValueOrDefault(),
o.visits.GetValueOrDefault(),
(double)o.bounce_rate.GetValueOrDefault()
);
return query;
}
return null;
}
public class OminitureStats
{
public OminitureStats(int PageViews, int MonthlyUniqueVisitors, int Visits, double BounceRate)
{
this.PageViews = PageViews;
this.MonthlyUniqueVisitors = MonthlyUniqueVisitors;
this.Visits = Visits;
this.BounceRate = BounceRate;
this.PagesPerVisit = Math.Round((double)(PageViews / Visits), 1);
}
public OminitureStats(int PageViews, int MonthlyUniqueVisitors, int Visits, double BounceRate, double PagesPerVisit)
{
this.PageViews = PageViews;
this.MonthlyUniqueVisitors = MonthlyUniqueVisitors;
this.Visits = Visits;
this.BounceRate = BounceRate;
this.PagesPerVisit = PagesPerVisit;
}
public int PageViews { get; set; }
public int MonthlyUniqueVisitors { get; set; }
public int Visits { get; set; }
public double PagesPerVisit { get; set; }
public double BounceRate { get; set; }
}

IIRC you can do all the sums in one go (as long as the query is translated to SQL) with
var sums = query.GroupBy(q => 1)
.Select(g => new
{
PageViews = g.Sum(q => q.PageViews),
Visits = g.Sum(q => q.Visits),
// etc etc
})
.Single();
This will give you one object which contains all the sums as separate properties.

I found out why it was throwing the NotSupportedException. I learned that Linq to Entity does not support constructors with parameters, So deleted the constructors and made changes in my query. I am a novice C# programmer, so let me know if my solution could be improved, but as of right now it is working fine.
public class OminitureStats
{
public int PageViews { get; set; }
public int MonthlyUniqueVisitors { get; set; }
public int Visits { get; set; }
public double PagesPerVisit { get; set; }
public double BounceRate { get; set; }
}
private IQueryable<OminitureStats> GetOmnitureDataAsQueryable(int? fnsId, int dateRange)
{
var yesterday = DateTime.Today.AddDays(-1);
var nDays = yesterday.AddDays(-dateRange);
if (fnsId.HasValue)
{
IQueryable<OminitureStats> query = from o in lhDB.omniture_stats
where o.fns_id == fnsId
&& o.date <= yesterday
&& o.date > nDays
select new OminitureStats() {
o.page_views.GetValueOrDefault(),
o.monthly_unique.GetValueOrDefault(),
o.visits.GetValueOrDefault(),
(double)o.bounce_rate.GetValueOrDefault()
};
return query;
}
return null;
}

Distinct with custom comparer

Trying to use Distinct() using a custom comparer and it gives me the error:
cannot be inferred from the usage. Try specifying the type arguments explicitly
The Default comparer works fine but doesn't give the results I expect of course. How can I fix this?
public class TimeEntryValidation
{
public string EmployeeID { get; set; }
public string EmployeeLocation { get; set; }
public string EmployeeDepartment { get; set; }
public int RowIndex { get; set; }
}
public class MyRowComparer : IEqualityComparer<TimeEntryValidation>
{
public bool Equals(TimeEntryValidation x, TimeEntryValidation y)
{
return (x.EmployeeDepartment == y.EmployeeDepartment && x.EmployeeLocation == y.EmployeeLocation);
}
public int GetHashCode(TimeEntryValidation obj)
{
return obj.EmployeeID.GetHashCode();
}
}
void Query(List<TimeEntryValidation> listToQuery)
{
var groupedData =
from oneValid in listToQuery
group oneValid by oneValid.EmployeeID
into g
where g.Count() > 1
select new {DoubleItems = g};
var listItems = groupedData.Distinct(new MyRowComparer());
}

The type of groupedData is some IEnumerable<{an anonymous type}> whereas MyRowComparer is IEqualityComparer<TimeEntryValidation>
It's unclear whether you intended listItems to be a list of groups, or whether you wanted the actual items themselves.
If it's the latter, you probably want something like this:
void Query(List<TimeEntryValidation> listToQuery)
{
var groupedData = from oneValid in listToQuery
group oneValid by oneValid.EmployeeID
into g
where g.Count() > 1
select g ;
var listItems = groupedData.SelectMany(group => group).Distinct(new MyRowComparer());
//listItems is now an IEnumerable<TimeEntryValidation>
}