Patrick Patrick - 2 months ago 13
C# Question

Linq distinct record containing keywords

I need to return a distinct list of records based on a car keywords search like: "Alfa 147"

The problem is that, as I have 3 "Alfa" cars, it returns 1 + 3 records (it seems 1 for the Alfa and 147 result, and 3 for the Alfa result)

EDIT:

The SQL-Server Query look something like this:

SELECT DISTINCT c.Id, c.Name /*, COUNT(Number of Ads in the KeywordAdCategories table with those 2 keywords) */
FROM Categories AS c
INNER JOIN KeywordAdCategories AS kac ON kac.Category_Id = c.Id
INNER JOIN KeywordAdCategories AS kac1 ON kac.Ad_Id = kac1.Ad_Id AND kac1.Keyword_Id = (SELECT Id FROM Keywords WHERE Name = 'ALFA')
INNER JOIN KeywordAdCategories AS kac2 ON kac1.Ad_Id = kac2.Ad_Id AND kac2.Keyword_Id = (SELECT Id FROM Keywords WHERE Name = '147')


My LINQ query is:

var query = from k in keywordQuery where splitKeywords.Contains(k.Name)
join kac in keywordAdCategoryQuery on k.Id equals kac.Keyword_Id
join c in categoryQuery on kac.Category_Id equals c.Id
join a in adQuery on kac.Ad_Id equals a.Id
select new CategoryListByKeywordsDetailDto
{
Id = c.Id,
Name = c.Name,
SearchCount = keywordAdCategoryQuery.Where(s => s.Category_Id == c.Id).Where(s => s.Keyword_Id == k.Id).Distinct().Count(),
ListController = c.ListController,
ListAction = c.ListAction
};

var searchResults = new CategoryListByBeywordsListDto();

searchResults.CategoryListByKeywordsDetails = query.Distinct().ToList();


The entities are:

public class Keyword
{
// Primary properties
public int Id { get; set; }
public string Name { get; set; }
}
// Keyword Sample Data:
// 1356 ALFA
// 1357 ROMEO
// 1358 145
// 1373 147

public class Category
{
// Primary properties
public int Id { get; set; }
public string Name { get; set; }
}
// Category Sample Data
// 1 NULL 1 Carros
// 2 NULL 1 Motos
// 3 NULL 2 Oficinas
// 4 NULL 2 Stands
// 5 NULL 1 Comerciais
// 8 NULL 1 Barcos
// 9 NULL 1 Máquinas
// 10 NULL 1 Caravanas e Autocaravanas
// 11 NULL 1 Peças e Acessórios
// 12 1 1 Citadino
// 13 1 1 Utilitário
// 14 1 1 Monovolume

public class KeywordAdCategory
{
[Key]
[Column("Keyword_Id", Order = 0)]
public int Keyword_Id { get; set; }

[Key]
[Column("Ad_Id", Order = 1)]
public int Ad_Id { get; set; }

[Key]
[Column("Category_Id", Order = 2)]
public int Category_Id { get; set; }
}
// KeywordAdCategory Sample Data
// 1356 1017 1
// 1356 1018 1
// 1356 1019 1
// 1357 1017 1
// 1357 1018 1
// 1357 1019 1
// 1358 1017 1
// 1373 1019 1

public class Ad
{
// Primary properties
public int Id { get; set; }
public string Title { get; set; }
public string TitleStandard { get; set; }
public string Version { get; set; }
public int Year { get; set; }
public decimal Price { get; set; }

// Navigation properties
public Member Member { get; set; }
public Category Category { get; set; }
public IList<Feature> Features { get; set; }
public IList<Picture> Pictures { get; set; }
public IList<Operation> Operations { get; set; }
}

public class AdCar : Ad
{
public int Kms { get; set; }
public Make Make { get; set; }
public Model Model { get; set; }
public Fuel Fuel { get; set; }
public Color Color { get; set; }
}
// AdCar Sample Data
// 1017 Alfa Romeo 145 1.6TDI 2013 ALFA ROMEO 145 1.6TDI 2013 12 2 1.6TDI 1000 1 2013 1 20000,0000 2052 AdCar
// 1018 Alfa Romeo 146 1.6TDI 2013 ALFA ROMEO 146 1.6TDI 2013 12 2 5 1.6TDI 1000 2 2013 1 20000,0000 2052 AdCar
// 1019 Alfa Romeo 147 1.6TDI 2013 ALFA ROMEO 147 1.6TDI 2013 12 2 6 1.6TDI 1000 3 2013 1 20000,0000 2052 AdCar


The result I expect for the search of "ALFA" is "Cars: 3" and for the search of "ALFA 147" is "Cars: 1" and actually the result I get is "Cars: 1 \n Cars: 3"

Answer

Fiuu, this was brain-wreck. I splited query in several pieces, but it's executed as a whole at the end (var result). And I returned anonymous class, but intention is clear.

Here is the solution:

var keywordIds = from k in keywordQuery
                    where splitKeywords.Contains(k.Name)
                    select k.Id;

var matchingKac = from kac in keywordAdCategories
            where keywordIds.Contains(kac.Keyword_Id)
            select kac;

var addIDs = from kac in matchingKac
                group kac by kac.Ad_Id into d
                where d.Count() == splitKeywords.Length
                select d.Key;

var groupedKac = from kac in keywordAdCategoryQuery
                where addIDs.Contains(kac.Ad_Id)
                group kac by new { kac.Category_Id, kac.Ad_Id };

var result = from grp in groupedKac
                group grp by grp.Key.Category_Id into final
                join c in categoryQuery on final.Key equals c.Id
                select new
                {
                    Id = final.Key,
                    Name = c.Name,
                    SearchCount = final.Count()
                };

// here goes result.ToList() or similar
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