EF Core Include ThenInclude 过滤器

Question

I have the following DB Structure

Tenant (one to many) -> Site (one to many) -> SiteUrl

public sealed class Tenant : Entity
{
    public IReadOnlyCollection<Site> Sites => _sites?.ToList();
}

public class Site : Entity
{
    public IReadOnlyCollection<SiteUrl> Urls => _urls?.ToList();
}

I am trying to query the data using EF core 5.0 with the following

var t = await tenants
                    .Include(t => t.Sites)
                    .ThenInclude(s => s.Urls.Where(su => su.Url == url))
                    .ProjectTo<TenantContextDto>(mapper.ConfigurationProvider)
                    .FirstOrDefaultAsync();

Basically im trying to get a tenant based on the url of a site and im not getting the results back im expecting. I have tried all kinds of variations of the code but have not been able to get it to find the correct tenant / site based on the url being searched for.

Any help / advice would be much appreciated

Thanks for all the replies all

In the DB I have Tenant 1

• Site 1
  • Localhost1
  • Localhost
• Site 2
  • www.testsite1.com
  • www.testsite2.com Tenant 2
• Site 3
  • www.testsite3.com

When I search for localhost I get back the correct Tenant, Correct Site but I get the url localhost1.

Gert Arnold: Thanks totally forgot that projection ignores includes, that was a great article you pointed me at thanks.

Answer 1

If you want tenants that have a matching site URL then:

var t = await tenants
    .Where(t => t.Sites.Any(s=> s.Url == url))
    .ProjectTo<TenantContextDto>(mapper.ConfigurationProvider)
    .FirstOrDefaultAsync();

Include / ThenInclude are used when you want to return an entity and eager load related entities and their respective related entities respectively. When using Automapper's ProjectTo or using Linq's Select you do not need to Eager load, the projection will load the data based on what is needed.

If you want to filter the sites within the tenant details (DTO) to only the data that matches the URL then your projection will need to be configured to look for only the records that match the criteria. If your DTO is including a structure for Sites within it, it will include all Sites for the matched Tenant, not just the site(s) with the target URL.

Answer 2

不要忘记，沿着 1:M 关系走另一条路（从 M 到 1）会更简单一些：

context.SiteUrls.Where(su => su.Url == url).Select(su => su.Site.Tenant) ...