MVC实体框架计数

Question

I would like to build a result like: CategoryID || Count(Searches) || CategoryName based on two Entity Framework based classes:

public class Category
{
    // Primary properties
    public int Id { get; set; }
    public string Name { get; set; }
    public string SearchPreviewControllerAction { get; set; }
}

public class Search
{
    // Primary properties
    public int Id { get; set; }
    public string SearchTitle { get; set; }
    public string SearchStandard { get; set; }
    public int CategoryId { get; set; }

    // Navigation properties
    public virtual Category Category { get; set; }
}

I already made a SearchPreview method that returns the Searches based on a search like "Aston Martin" that will find in all categories with the words "Aston Martin".

The challenge now is to build a method that returns, after the Search of the keywords "Aston Martin", in which categories there are those keywords including the count, like "Auto: 2 | Seeling point: 3 | Shop: 2"

I am trying to avoid a query for each category to count the number of Searches entry, and I would like to find a GroupBy solution, that takes the SearchPreview method already executed and extract the GroupBy Categories that it contains.

I am using the ViewModel SearchPreviewListCategoriesViewModel to map from the models using Automapper:

public class SearchPreviewListCategoriesViewModel
{
    public int CategoryID { get; set; }
    public string Name { get; set; }
    public string SearchPreviewControllerAction { get; set; }
    public int SearchCount { get; set; }
}

Hope somoeone can help me on this.

Thank you.

Regards,

Patrick.

Answer 1

Not sure how you're matching, but maybe something like this

from c in aCategories where c.Search.Any(s => s.SearchStandard.Contains("Aston Martin") == true) select new SearchPreviewListCategoriesViewModel { CategoryID = c.Id, Name = c.Name, SearchPreviewControllerAction = c.SearchPreviewControllerAction, SearchCount = (c.Search.Where(s => s.SearchStandard.Contains("Aston Martin") == true)).Count() };

where aCategories is your context access to the Category table.

Answer 2

Solution found to the problem:

Step 1:

Creation of a Data Transfer Object to take the Domain object and deliver it to the Presentation Web Layer:

public class SearchCategoriesListDto
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string SearchPreviewControllerAction { get; set; }
    public int SearchCount { get; set; }
}

Step 2:

Refacturing of the mapping between the DTO and the ViewModel in the Presentation Layer:

Mapper.CreateMap<SearchCategoriesListDto, SearchCategoriesListViewModel>();

Step 3:

Method to deliver the CategoryName, the Count by Category and the ControllerAction Name that will deliver the list for each Category list:

    public IList<SearchCategoriesListDto> SearchPreviewCategories(String keywords)
    {

        string keywordsClean = keywords;

        keywordsClean = keywordsClean.ToUpper();
        keywordsClean = StringUtils.StringSimbolsRemove(keywordsClean, HeelpResources.StringSymbolsToCleanFrom, HeelpResources.StringSymbolsToCleanTo);

        string[] splitKeywords = keywordsClean.Split(new Char[] { ' ' });

        var searchQuery = _searchRepository.Query;

        foreach (string keyword in splitKeywords)
        {
            searchQuery = searchQuery.Where(p => p.SearchStandard.Contains(keyword));
        }

        var categoryQuery = _categoryRepository.Query;

        var query = from sq in searchQuery
                    join cq in categoryQuery on sq.CategoryId equals cq.Id
                    select new SearchCategoriesListDto { 
                        Name = cq.Name, 
                        SearchCount = searchQuery.Where(c => c.CategoryId == cq.Id).Count(), 
                        SearchPreviewControllerAction = cq.SearchPreviewControllerAction 
                    };

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

        return searchResults;

}

Thanks for all the help I got from StackOverlow to solve this challenge.