Question

我有以下课程：

 public partial class Person : ModificationEntity
{
    public Person()
    {
        this.PersonCompanies = new List<PersonCompany>();
    }

    public System.Guid PersonId { get; set; }
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public string Email { get; set; }

    public virtual ICollection<PersonCompany> PersonCompanies { get; set; }
}

public partial class PersonCompany : ModificationEntity
{
    public System.Guid PersonCompanyId { get; set; }
    public System.Guid PersonId { get; set; }
    public System.Guid CompanyId { get; set; }

    public virtual Company Company { get; set; }
    public virtual Person Person { get; set; }
}

我需要查询给定公司名单的所有用户（List lstCompanyIds）。

所以我使用以下查询获取所有PersonCompanyId：

var qpc = (from c in lstCompanyIds
           join u in personCompanyService.GetPersonCompanies()
           on c equals u.CompanyId
           select u.PersonCompanyId).AsQueryable();

通过此查询，我想获得用户：

var query = from q in GetUsers()
             join q2 in qpc
             on q.PersonCompanies.Select(y => y.PersonCompanyId) equals q2
             select q;

但这会产生编译错误“join子句中某个表达式的类型不正确。在对'Join'的调用中类型推断失败。” 显然是因为我试图选择人员公司的集合。但是我该怎么做呢？（包含不起作用，因为我有两个要比较的集合......）

Answer 1

这里的问题是您要将IQueryable<Guid>与Guid进行比较。如果我理解正确，那就是你想要实现的目标：

IQueryable<Guid> companyIds = Enumerable.Empty<Guid>().AsQueryable(); //qpc in your question
IQueryable<Person> persons = Enumerable.Empty<Person>().AsQueryable(); //q in your question
var result = persons.Where(person => person.PersonCompanies
            .Any(company => companyIds.Contains(company.CompanyId)));

Answer 2

你能试试吗

    var qpc = (from res in
                      (from c in lstCompanyIds
                       join u in personCompanyService.GetPersonCompanies()
                       on c equals u.CompanyId
                       select u.PersonCompanyId)
                   join u in GetUser()
                  on res equals u.UserId
                  select u).AsQueryable();

我认为这应该有用

确保您要比较的所有ID都是System.Guid

类型

使用ICollection进行LINQ连接查询

2 个答案: