如何使用 linq 查询多个？

Question

如何使用 LINQ select 喜欢下面的代码，或者我可以在 LINQ 上使用 QueryMultiple 吗？。我知道如何使用 LINQ 加入两个模型列表，但在这种情况下，我不知道如何使用 LINQ 执行此操作。

var result = con.QueryMultiple(@"select gtp.status, gtp.p_id, gtp.p_name, gtp.p_price,
                      gca.c_type, gbr.bedtype, gtp.currency from t_package as gtp, category as gca,
                      bedrooms as gbr where gtp.c_id = gca.c_id and gtp.bedroom = gbr.bed_id
                      and gtp.p_id = @id;
                      select gtd.tdates_id, gtd.dfrom, gtd.dto from traveldates as gtd
                      where gtd.p_id = @id;
                      select ginc.in_id, ginc.name from inclusion as ginc 
                      where ginc.p_id = @id;
                      select con.con_id, con.name from tcondition as con
                      where con.p_id = @id;
                      select exc.ex_id, exc.name from exclusion as exc 
                      where exc.p_id = @id;
                      select fli.fl_id, fli.name from flightdetails as fli
                      where fli.p_id = @id;
                      select iti.it_id, iti.name, iti.description, iti.bmeal, iti.lmeal, iti.dmeal from itinerary as iti
                      where iti.p_id = @id;
                      select img.img_id, img.slides from imagetable as img
                      where img.p_id = @id;
                      select vi.visa_id, vi.name from visareq as vi
                      where vi.p_id = @id;
                      select ph.ph_id, ph.ph_loc, ph.ph_phtel from photel as ph 
                      where ph.p_id = @id;",
                       new { @id = id });
                var aTp = result.ReadSingle<AdminTP>();
                aTp.adminTDs = result.Read<AdminTD>().ToList();
                aTp.adminINCs = result.Read<AdminINC>().ToList();
                aTp.adminCONs = result.Read<AdminCON>().ToList();
                aTp.adminEXCs = result.Read<AdminEXC>().ToList();
                aTp.adminFLIs = result.Read<AdminFLI>().ToList();
                aTp.adminITIs = result.Read<AdminITI>().ToList();
                aTp.adminIMGs = result.Read<AdminIMG>().ToList();
                aTp.adminVIs = result.Read<AdminVI>().ToList();
                aTp.photels = result.Read<Photel>().ToList();
                return Json(aTp, JsonRequestBehavior.AllowGet);

假设 t_package、traveldates 和其他 table 是模型列表而不是数据库 table。

Answer 1

所以您有 Packages、TravelDates、Gincs、Cons、Flis 等序列，而且 Packages 和这些其他项目之间似乎存在一对多关系。

每个Package都有零个或多个TDates，每个TDates恰好属于一个Package，即外键PackageId所指的Package。

同理，每个Ginc都属于外键所指的Package，每个Con、Fli等都属于外键PackageId所指的唯一一个包：都是直接的一对多关系

Requirement: given a packageId, give me the Package with this Id, with its travel data, its Gincs, its Flis, and all its other items with strange names.

为了能够使用 LINQ 执行此操作，您需要有权访问 IQueryables。例如，通过 DbContext.DbSet<...>

int packageId = ...
IQueryable<Package> packages = ...
IQueryable<TDate> tDates = ...
IQueryable<Fli> Flis = ...
...

var result = packages.Where(package => package.Id == packageId).Select(package => new
{
    // Select the package properties that you plan to use:
    Id = package.Id,
    Name = package.Name,
    Status = package.Status,
    ...

    TDates = tDates.Where(tDate => tDate.PackageId == package.Id).Select(tDate => new
    {
        Id = tDate.Id,
        DateFrom = tDate.DateFrom,
        DateTo = tDate.DateTo,
        ...
    })
    .ToList(),

    Flis = flis.Where(fli => fli.PackageId == package.Id).Select(fli => new
    {
         ...
    })
    .ToList(),

    ... etc: 
});

Answer 2

我想你正在寻找联合命令，你可以使用Linq的查询符号或点符号。在进行联合之前，您需要执行您在评论中提到的 select ，以便附加的每个对象都属于同一类型。下面的代码是点符号，因为我觉得它更容易阅读：

string[] adminTDs = { "A", "B", "C" };
string[] adminINCs= { "D", "E", "F" };
string[] adminCONs = { "H", "I", "J" };
//Method Syntax
var MS = adminTDs
            .Union(adminINCs)
            .Union(adminCONs).ToList();

有关 LINQ 联合的更多信息，请访问 https://dotnettutorials.net/lesson/linq-union-method/。

如何使用 linq 查询多个？

How to QueryMultiple using linq?

c#

linq

asp.net

model-view-controller