首先，我想知道此查询是否是延迟加载或预先加载。我在两者上都读了很多，不知道我是否理解彼此之间的区别。
2- I获取此查询，此查询需要花费大量时间才能执行。当你看到这个查询时，任何人都有一些建议。我会做所有加速查询所需的修改。
注意：我只想了解您对此查询和方法的看法。
非常感谢。
public SearchLocationViewModel GetSearchLocationViewModel( string CivicNumber = null ,
string Street = null,
string City = null,
List<int?> ListCountryID = null,
List<int?> ListStateID = null,
int IsActive =1,
string SortField ="FileNumber",
string SortDirection = "asc" ,
List<int?> GrpDescID1 = null,
List<int?> GrpDescID2 = null,
List<int?> GrpDescID3 = null,
List<int?> GrpDescID4 = null,
int LocationTypeID = -1,
List<int?> ListUsageID = null)
{
if (GrpDescID1 == null)
{
GrpDescID1 = new List<int?>();
}
if (GrpDescID2 == null)
{
GrpDescID2 = new List<int?>();
}
if (GrpDescID3 == null)
{
GrpDescID3 = new List<int?>();
}
if (GrpDescID4 == null)
{
GrpDescID4 = new List<int?>();
}
if (ListCountryID == null)
{
ListCountryID = new List<int?>();
}
if (ListStateID == null)
{
ListStateID = new List<int?>();
}
if (ListUsageID == null)
{
ListUsageID = new List<int?>();
}
GrpDescID1.Remove(GrpDescID1.SingleOrDefault(p => p < 0));
GrpDescID2.Remove(GrpDescID2.SingleOrDefault(p => p < 0));
GrpDescID3.Remove(GrpDescID3.SingleOrDefault(p => p < 0));
GrpDescID4.Remove(GrpDescID4.SingleOrDefault(p => p < 0));
ListCountryID.Remove(ListCountryID.SingleOrDefault(p => p < 0));
ListStateID.Remove(ListStateID.SingleOrDefault(p => p < 0));
ListUsageID.Remove(ListUsageID.SingleOrDefault(p => p < 0));
int lang = BaseStaticClass.CurrentLangID();
int UserID = Convert.ToInt32(Session["UserID"]);
SearchLocationViewModel ViewModel = InitSearchViewModel();
IGrpRepository repGrp = new GrpRepository(_db);
ICountryRepository repCountry = new CountryRepository(_db);
IProvinceRepository repProvince = new ProvinceRepository(_db);
ViewModel.Perm = repPermission;
ViewModel. CivicNumber = CivicNumber ;
ViewModel. Street = Street;
ViewModel. City = City;
ViewModel. IsActive =IsActive;
ViewModel. SortField =SortField;
ViewModel. SortDirection = SortDirection ;
ViewModel.ListCountry = repCountry.GetCountryForSearchByUser(true,UserID);
ViewModel.ListProvince = repProvince.GetProvinceSearchByUserID(true, UserID);
ViewModel.ListGrpDescID1 =GrpDescID1;
ViewModel.ListGrpDescID2 = GrpDescID2;
ViewModel.ListGrpDescID3 = GrpDescID3;
ViewModel.ListGrpDescID4 = GrpDescID4;
ViewModel.ListCountryID = ListCountryID;
ViewModel.ListStateID = ListStateID;
ViewModel.LocationTypeID = LocationTypeID;
ViewModel.ListUsageID = ListUsageID;
var LocationType = new SelectList(repGeneric.GetTextByCurrentLang<LocationType, LocationTypeText>(), "ID", "Txt").ToList();
bc.AddDropdownSearchValueNoNew(ref LocationType);
var ListUsage = new SelectList(repGeneric.GetTextByCurrentLang<Usage, UsageText>(), "ID", "Txt").ToList();
ViewModel.ListUsage = ListUsage;
ViewModel.ListLocationType = LocationType;
var ListGrp1 = new SelectList(repGrp.GetAllGrpDescTextForUserByLevel(UserID, 1).AsEnumerable(), "GrpDescID", "GrpDescTxt").ToList();
var ListGrp2 = new SelectList(repGrp.GetAllGrpDescTextForUserByLevel(UserID, 2).AsEnumerable(), "GrpDescID", "GrpDescTxt").ToList();
var ListGrp3 = new SelectList(repGrp.GetAllGrpDescTextForUserByLevel(UserID, 3).AsEnumerable(), "GrpDescID", "GrpDescTxt").ToList();
var ListGrp4 = new SelectList(repGrp.GetAllGrpDescTextForUserByLevel(UserID, 4).AsEnumerable(), "GrpDescID", "GrpDescTxt").ToList();
var t1 = ListGrp1.Select(s => (int?)Convert.ToInt32(s.Value));
var t2 = ListGrp2.Select(s => (int?)Convert.ToInt32(s.Value));
var t3 = ListGrp3.Select(s => (int?)Convert.ToInt32(s.Value));
var t4 = ListGrp4.Select(s => (int?)Convert.ToInt32(s.Value));
ViewModel.ListGrp1 = ListGrp1;
ViewModel.ListGrp2 = ListGrp2;
ViewModel.ListGrp3 = ListGrp3;
ViewModel.ListGrp4 = ListGrp4;
ViewModel.ListGrpTogether = new List<SelectListItem>();
if(ViewModel.GrpName1 != "")
ViewModel.ListGrpTogether.Add(new SelectListItem() { Text = ViewModel.GrpName1 ,Value = "1"});
if (ViewModel.GrpName2 != "")
ViewModel.ListGrpTogether.Add(new SelectListItem() { Text = ViewModel.GrpName2, Value = "2" });
if (ViewModel.GrpName3 != "")
ViewModel.ListGrpTogether.Add(new SelectListItem() { Text = ViewModel.GrpName3, Value = "3" });
if (ViewModel.GrpName4 != "")
ViewModel.ListGrpTogether.Add(new SelectListItem() { Text = ViewModel.GrpName4, Value = "4" });
ViewModel.ListGrpTogether.Insert(0, new SelectListItem() { Text = ViewRes.GeneralString.Choose, Value = "-1", Selected = true });
int iUserID = Convert.ToInt32(Session["UserID"]);
//this is use for Permission
//Get all the user permission about group and province
IEnumerable<int?> usrGrpDesc = _db.UserGroupDescs.Where(p => p.UserID == iUserID).Select(s => s.GrpDescID);
IEnumerable<int?> usrProvince = _db.UserProvinces.Where(p => p.UserID == iUserID).Select(s => s.PrvID);
var ListLocation = from s in _db.Locations.Where(p =>
p.IsDelete == false &&
(IsActive < 0 || IsActive == (p.IsActive == true ? 1 : 0)) &&
(LocationTypeID < 0 || LocationTypeID == p.LocationTypeID) &&
(City == null || p.Address.City.CityName.Contains(City)) &&
(ListUsageID.Count() == 0 || p.Premises.Select(gs => gs.UsageID).Intersect(ListUsageID).Any()) &&
(ListCountryID.Count() == 0 || ListCountryID.Any(pl => pl == p.Address.City.Province.Country.CtryID)) &&
(ListStateID.Count() == 0 || ListStateID.Any(pl => pl == p.Address.City.Province.PrvID)) &&
(Street == null || p.Address.Street.Contains(Street)) &&
(CivicNumber == null || p.Address.CivicNumber.Contains(CivicNumber)) &&
((GrpDescID1.Count() == 0 )|| p.GroupLocations.Select(gs => gs.GrpDescID).Intersect(GrpDescID1).Any()) &&
((GrpDescID2.Count() == 0)|| p.GroupLocations.Select(gs => gs.GrpDescID).Intersect(GrpDescID2).Any()) &&
((GrpDescID3.Count() == 0) || p.GroupLocations.Select(gs => gs.GrpDescID).Intersect(GrpDescID3).Any()) &&
((GrpDescID4.Count() == 0 ) || p.GroupLocations.Select(gs => gs.GrpDescID).Intersect(GrpDescID4).Any()) &&
(p.GroupLocations.Select(gs => gs.GrpDescID).Intersect(usrGrpDesc).Any()) &&
((p.Address.City == null || usrProvince.Any(ps => ps.Value == p.Address.City.PrvID)))
)
select new LocationViewModel()
{
LocationID = s.LocationID,
LocationTypeID = s.LocationTypeID,
Long = s.Address.Longitude,
Lat = s.Address.Latitude,
FileNumber = s.LocationFile,
State = s.Address.City.Province.PrvName,
City = s.Address.City.CityName,
Address = s.Address.CivicNumber + " " + s.Address.Street,
Status = s.LocationType.LocationTypeTexts.Where(h => h.Txt != "" && h.LangID == lang || h.LangID == 1).OrderByDescending(g => g.LangID).FirstOrDefault().Txt,
ListGroupe1 = s.GroupLocations.Where(g=>g.GrpDesc.Grp.GrpLevel == 1).Select(grpLoc => grpLoc.GrpDesc.GrpDescTexts.Where(h => h.GrpDescTxt != "" && (h.LangID == lang || h.LangID == 1)).OrderByDescending(g => g.LangID).FirstOrDefault()).Select(txt => txt.GrpDescTxt),
ListGroupe2 = s.GroupLocations.Where(g => g.GrpDesc.Grp.GrpLevel == 2).Select(grpLoc => grpLoc.GrpDesc.GrpDescTexts.Where(h => h.GrpDescTxt != "" && (h.LangID == lang || h.LangID == 1)).OrderByDescending(g => g.LangID).FirstOrDefault()).Select(txt => txt.GrpDescTxt),
ListGroupe3 = s.GroupLocations.Where(g=>g.GrpDesc.Grp.GrpLevel == 3).Select(grpLoc => grpLoc.GrpDesc.GrpDescTexts.Where(h => h.GrpDescTxt != "" && (h.LangID == lang || h.LangID == 1)).OrderByDescending(g => g.LangID).FirstOrDefault()).Select(txt => txt.GrpDescTxt),
ListGroupe4 = s.GroupLocations.Where(g=>g.GrpDesc.Grp.GrpLevel == 4).Select(grpLoc => grpLoc.GrpDesc.GrpDescTexts.Where(h => h.GrpDescTxt != "" && (h.LangID == lang || h.LangID == 1)).OrderByDescending(g => g.LangID).FirstOrDefault()).Select(txt => txt.GrpDescTxt),
DefaultImgPath = s.LocationPictures.Where(p=>p.IsDefault == true && p.IsActive == true).FirstOrDefault().FilePath,
HasPremises = s.Premises.Any(p => p.IsActive == true && p.IsDelete == false)
};
ViewModel.ListLocation = ListLocation.ToList();
return ViewModel;
}
答案 0 :(得分：0)
如果您正在使用它，并且它可以正常工作，那么您可能会延迟加载，因为您没有对.Include()进行任何调用。
答案 1 :(得分：0)
延迟加载是推迟对象的初始化，直到需要它为止。如果您将ListLocation返回给其来电者，正如您上面所写的那样，没有.ToList()（或其他），那么您就会懒散地消耗它。
预先加载是在查询定义时收集查询的结果。在这种情况下，它将一次性检索LINQ查询的结果（在查询被构造时）。通常.ToList()或.Single()或其他人会为您执行此操作。
我怀疑你的代码后面的LINQ查询（ var ListLocation）会消耗你的结果。上面的代码使用了一种延迟加载的方法。
您正在显示您正在呼叫.ToList()，因此您确实正在使用预先加载;即使它是在不同的声明/代码行上。
性能：我不是100％因为这是你的性能问题，但我会使用扩展方法.WhereIf()将你的LINQ重构成这样的东西。这是一个更容易阅读和写作。
var ListLocation = from s in _db.Locations
.Where(p => p.IsDelete == false)
.WhereIf(IsActive >= 0, p=> IsActive == (p.IsActive == true ? 1 : 0))
.WhereIf(LocationTypeID >= 0, p=> LocationTypeID == p.LocationTypeID
.WhereIf(City!=null, p=> p.Address.City.CityName.Contains(City)) //etc