Question

基本上，我有很多公司可以有很多办公室，如何让我的查询显示这个，我有：问题（或者在我看来是这样），我正在检索一家公司3次（例如下面的例子），当我只收到一家公司和许多办公室时，我的查询是否完全错误？

//companies = _repo.All<Companies>();
//mainoffice = _repo.All<Office>();

        var dto = companies
           .Join(mainoffice, x => x._ID, y => y.CompanyID, (x, y) => new
            {
                mycompany = x,
                myoffice = y,
            })
            .Select(x => new
                {
                    ID = x.mycompany._ID,
                    Offices = x.myoffice
                });

enter image description here

然而，如果我加入团体，我会得到我想要的东西但我找回那些没有办公室的公司......

  var dto = companies
           .GroupJoin(mainoffice, x => x._ID, y => y.CompanyID, (x, y) => new
            {
                mycompany = x,
                myoffice = y,
            })
            .Select(x => new
                {
                    ID = x.mycompany._ID,
                    Offices = x.myoffice
                });

更新：另外1个嵌套结果集......

        var areascovered = repo.All<OfficePostCode>();

        var filter = repo.All<PostCodeDistrict>()
            .Where(x => x.Region.StartsWith(postcode))
            .Join(areascovered, x => x.PostCodeID, y => y.PostCodeID, (x, y) =>
                 new
                 {
                     Postcode = x.PostCode,
                     Region = x.Region,
                     OfficeID = y.OfficeID
                 });

        var mainoffice = repo.All<Office>();

        var dto = companies
            .Select(company => new
            {
                ID = company._ID,
                Offices = mainoffice.Select(office => new
                {
                    CompanyID = office.CompanyID,
                    Name = office.Name,
                    Tel = office.Tel,
                    RegionsCovered = filter.Where(f => f.OfficeID == office.OfficeID)
                })
                .Where(y => y.CompanyID == company._ID)// && y.RegionsCovered.Any())
            })
            .Where(pair => pair.Offices.Any());

Answer 1

您不需要加入，只需要嵌套选择。尝试这样的事情：

from company in companies
select new
{
   ID = company._ID,
   Offices = mainoffice.Where(office => office.CompanyID == company._ID)
}

如果您不希望公司没有办公室的条目，那么试试这个：

from company in companies
let offices = mainoffice.Where(office => office.CompanyID == company._ID)
where offices.Any()
select new
{
   ID = company._ID,
   Offices = offices
}

显式lambda版本（点表示法）：

第一个：

companies.Select(company => new
{
    ID = company._ID,
    Offices = mainoffice.Where(office => office.CompanyID == company._ID)
});

没有办事处的公司，已删除：

companies.Select(company => new
{
    ID = company._ID,
    Offices = mainoffice.Where(office => office.CompanyID == company._ID)
})
.Where(pair => pair.Offices.Any());

Answer 2

没有必要和办公室一起加入公司，在这样的加入中你会看到每家公司都有办公室的数量，我想你可以尝试下面的说法：

companies.SelectMany(x=>x.Offices).Select(x=>new {ID = x.CompanyID, Office = x})

或

offices.GroupBy(x=>x.CompanyID).Select( x=>new {ID = Key, Offices = x});

我假设你在每个办公室都有公司ID。

如果您还想拥有完整的公司，请执行cxan

var officeGroups = 
    offices.GroupBy(x=>x.CompanyID).Select( x=>new {ID = Key, Offices = x});

var result = from c in companies
               join o in officeGroups on c.ID equals o.ID
               select new {Company = c, Offices = o.Offices};

Linq：项目结果

2 个答案: