MVC 多对多仅在代码中首先获取具有特定类型的实体

Question

我在 Company 和 CompanyType 之间存在多对多关系

我想获得一个下拉列表，其中包含 CompanyType.Name 为 "Client" 的公司。 IE。客户公司列表。

我如何在 linq 中做到这一点？

我基本上想做以下但在 linq

var clientCompanies = db.Companies.SqlQuery(@"SELECT  c.*
FROM    Companies AS c
JOIN    CompanyTypeCompanies AS ctc ON ctc.Company_ID = c.ID
JOIN    CompanyTypes AS ct ON ctc.CompanyType_ID = ct.ID
WHERE   ct.Name = 'Client'").ToList();

Answer 1

您可以使用 include 语句，如果它在表之间具有适当的外键关系

var clientCompanies = db.CompanyTypes
.Where(ct => ct.Name == "Client").Include(ct => ct.CompanyTypeCompanies).Include(ct => ct.Companies).Select(ct => ct.Companies).ToList();

正在启动class

public void ConfigureServices(IServiceCollection services)
{
    ...

    services.AddMvc()
        .AddJsonOptions(
            options => options.SerializerSettings.ReferenceLoopHandling = Newtonsoft.Json.ReferenceLoopHandling.Ignore
        );

    ...
}

MVC 多对多仅在代码中首先获取具有特定类型的实体

MVC many to many get entities with of certain type only in code first

linq

many-to-many

code-first

linq-to-sql