I have a MySQL DB that I'm trying to query with the Entity Framework.
I have a Match table that looks like this:
match_id, winning_hero1, winning_hero2, winning_hero3, winning_hero4, winning_hero5
with a winning_hero being identified by an integer.
given a list of hero ids, I want to return all matches where these heroes were all on the winning team together.
something like this:
public List<MatchEntity> GetAllMatchesWithWinningHeroes(List<int> heroList)
{
List<MatchEntity> matchList = null;
using (var context = new dotaEntities())
{
switch (heroList.Count)
{
case 1:
matchList = context.MatchEntities.Where(m => m.winning_hero1 == heroList[0]
|| m.winning_hero2 == heroList[0]
|| m.winning_hero3 == heroList[0]
|| m.winning_hero4 == heroList[0]
|| m.winning_hero5 == heroList[0]).ToList();
break;
case 2:
matchList = context.MatchEntities.Where(m => (m.winning_hero1 == heroList[0]
|| m.winning_hero2 == heroList[0]
|| m.winning_hero3 == heroList[0]
|| m.winning_hero4 == heroList[0]
|| m.winning_hero5 == heroList[0])
&& (m.winning_hero1 == heroList[1]
|| m.winning_hero2 == heroList[1]
|| m.winning_hero3 == heroList[1]
|| m.winning_hero4 == heroList[1]
|| m.winning_hero5 == heroList[1])).ToList();
break;
case 3:
//etc..
}
return matchList;
}
}
Is there a "nicer" way to go about selecting these matches?
Thank you.
What you need is this:
using (var context = new dotaEntities())
{
var matchList = context.MatchEntities.Where(m =>
heroList.Contains(m.winning_hero1) &&
heroList.Contains(m.winning_hero2) &&
heroList.Contains(m.winning_hero3) &&
heroList.Contains(m.winning_hero4) &&
heroList.Contains(m.winning_hero5)).ToList();
}
But, your data design is wrong. In your Match table, you should only have a MatchID (PK), and probably MatchName or MatchDate, and in your Hero table, you should have HeroID (PK), HeroName,... Then, you should have a third table (MatchHero) just to create a many-to-many relationship between the two tables. In your MatchHero table, you'll have MatchID and HeroID.
I think this is what you want:
using (var context = new dotaEntities())
{
matchList = context.MatchEntities.Where(m=>
( heroList.Contains(m.winning_hero1)?1:0 +
heroList.Contains(m.winning_hero2)?1:0 +
heroList.Contains(m.winning_hero3)?1:0 +
heroList.Contains(m.winning_hero4)?1:0 +
heroList.Contains(m.winning_hero5)?1:0
) == heroList.Count
).ToList();
}
This assumes that all winning_heros are different.
Related
Code
if(Model.CurrentStatus == 1 || Model.CurrentStatus == 2)
{
//can display those records..
}
else if((Model.CurrentStatus == 3 || Model.CurrentStatus == 4) && Model.Date != null)
{
if(Model.Date <= 30 days)
{
//can display those records..
}
}
I have tried the following code and unable to complete it fully as expected
#Html.Partial("Filter", new IndexModel()
{
Id = Model.Id,
Collection = Model.Collection.Where((a => a.CurrentStatus == 1 || a.CurrentStatus == 2)
&& )
})
How to convert the above if condition to linq in cshtml. Thanks
the else-if relationship is an OR relationship. So simply combine the two lines. the inner nested if inside the else if is an AND relationship. This would go into the second set of parentheses
Collection = Model.Collection.Where
(
(a => a.CurrentStatus == 1 || a.CurrentStatus == 2) ||
((a.CurrentStatus == 3 || a.CurrentStatus == 4) && a.Date != null && a.Date <= 30)
)
EDIT:
Here is another suggestion: extract the readable code into an own method that evaluates the condition and returns the boolean result. This way you can make a predicate that can be accepted by the Where method:
private bool IsForDisplay( ModelDataType Model )
{
if(Model.CurrentStatus == 1 || Model.CurrentStatus == 2)
{
//can display those records..
return true;
}
else if((Model.CurrentStatus == 3 || Model.CurrentStatus == 4) && Model.Date != null)
{
if(Model.Date <= 30 days)
{
//can display those records..
return true;
}
}
return false;
}
now you can use it simply in the linq expression:
#Html.Partial("Filter", new IndexModel()
{
Id = Model.Id,
Collection = Model.Collection.Where(a => IsForDisplay(a))
});
I have a large project where I have dozens of linq statements where I am looking for a matching record by checking several fields to see if they match or both field and compared field are null.
var testRecord = new { firstField = "bob", secondField = (string)null, thirdField = "ross" };
var matchRecord = dataContext.RecordsTable.FirstOrDefault(vi =>
(vi.first == testRecord.firstField || ((vi.first == null || vi.first == string.Empty) && testRecord.firstField == null))
&& (vi.second == testRecord.secondField || ((vi.second == null || vi.second == string.Empty) && testRecord.secondField == null))
&& (vi.third == testRecord.thirdField || ((vi.third == null || vi.third == string.Empty) && testRecord.thirdField == null)));
//do stuff with matchRecord
Ideally I would replace all that duplicated code (used around 50 times across the system I'm working on) with something like the following
Expression<Func<string, string, bool>> MatchesOrBothNull = (infoItem, matchItem) => (
infoItem == matchItem || ((infoItem == null || infoItem == string.Empty) && matchItem == null));
var matchRecord = dataContext.RecordsTable.FirstOrDefault(vi =>
MatchesOrBothNull(vi.first, testRecord.firstField)
&& MatchesOrBothNull(vi.second, testRecord.secondField)
&& MatchesOrBothNull(vi.third, testRecord.thirdField));
//do stuff with matchRecord
My question is two-fold: First, is there a matched or both null function already available? (I've looked without luck).
Second, the code block above compiles, but throws a "no supported translation to sql" error, is there a way to have a function in the where clause? I know that there is a translation because it works if I don't pull it into the function. How can I get that translated?
First of all you can check whether string is null or empty with single code which is called : String.IsNullOrEmpty(vi.first). You need a method like this one :
public bool MatchesOrBothNull(string first,string second){
if(first==second||String.IsNullOrEmpty(first)||String.IsNullOrEmpty(second))
return true;
else return false;
}
You can use it in where clause
var matchRecord = dataContext.RecordsTable.Where(vi =>
MatchesOrBothNull(vi.first, testRecord.firstField)
&& MatchesOrBothNull(vi.second, testRecord.secondField)
&& MatchesOrBothNull(vi.third, testRecord.thirdField)
).FirstOrDefault();
I need to perform a count operation on this Entity Framework (EF6) data set using a relatively complex expression as a WHERE clause and expecting it to return about 100k records.
The count operation is obviously where records are materialized and therefore the slowest of operations to take place. The count operation is taking about 10 seconds in our production environment which is unacceptable.
Note that the operation is performed on the DbSet directly (db being the Context class), so no lazy loading should be taking place.
How can I further optimize this query in order to speed up the process?
The main use case is displaying an index page with multiple filter criteria but the the function is also used for writing generic queries to the ParcelOrderstable as required for other operations in the service classes which might be a bad idea resulting in very complex queries resulting from laziness and might potentially be a future problem.
The count is later used for pagination, and a much smaller number of records (e.g. 500) is actually displayed. This is a database-first project using SQL Server.
ParcelOrderSearchModel is a C#-class that serves to encapsualte query parameters and is used exclusively by service classes in order to call the GetMatchingOrdersfunction.
Note that on the majority of calls, the majority of the parameters of ParcelOrderSearchModel will be null.
public List<ParcelOrderDto> GetMatchingOrders(ParcelOrderSearchModel searchModel)
{
// cryptic id known --> allow public access without login
if (String.IsNullOrEmpty(searchModel.KeyApplicationUserId) && searchModel.ExactKey_CrypticID == null)
throw new UnableToCheckPrivilegesException();
Func<ParcelOrder, bool> userPrivilegeValidation = (x => false);
if (searchModel.ExactKey_CrypticID != null)
{
userPrivilegeValidation = (x => true);
}
else if (searchModel.KeyApplicationUserId != null)
userPrivilegeValidation = privilegeService.UserPrivilegeValdationExpression(searchModel.KeyApplicationUserId);
var criteriaMatchValidation = CriteriaMatchValidationExpression(searchModel);
var parcelOrdersWithNoteHistoryPoints = db.HistoryPoint.Where(hp => hp.Type == (int)HistoryPointType.Note)
.Select(hp => hp.ParcelOrderID)
.Distinct();
Func<ParcelOrder, bool> completeExpression = order => userPrivilegeValidation(order) && criteriaMatchValidation(order);
searchModel.PaginationTotalCount = db.ParcelOrder.Count(completeExpression);
// todo: use this count for pagination
}
public Func<ParcelOrder, bool> CriteriaMatchValidationExpression(ParcelOrderSearchModel searchModel)
{
Func<ParcelOrder, bool> expression =
po => po.ID == 1;
expression =
po =>
(searchModel.KeyUploadID == null || po.UploadID == searchModel.KeyUploadID)
&& (searchModel.KeyCustomerID == null || po.CustomerID == searchModel.KeyCustomerID)
&& (searchModel.KeyContainingVendorProvidedId == null || (po.VendorProvidedID != null && searchModel.KeyContainingVendorProvidedId.Contains(po.VendorProvidedID)))
&& (searchModel.ExactKeyReferenceNumber == null || (po.CustomerID + "-" + po.ReferenceNumber) == searchModel.ExactKeyReferenceNumber)
&& (searchModel.ExactKey_CrypticID == null || po.CrypticID == searchModel.ExactKey_CrypticID)
&& (searchModel.ContainsKey_ReferenceNumber == null || (po.CustomerID + "-" + po.ReferenceNumber).Contains(searchModel.ContainsKey_ReferenceNumber))
&& (searchModel.OrKey_Referencenumber_ConsignmentID == null ||
((po.CustomerID + "-" + po.ReferenceNumber).Contains(searchModel.OrKey_Referencenumber_ConsignmentID)
|| (po.VendorProvidedID != null && po.VendorProvidedID.Contains(searchModel.OrKey_Referencenumber_ConsignmentID))))
&& (searchModel.KeyClientName == null || po.Parcel.Name.ToUpper().Contains(searchModel.KeyClientName.ToUpper()))
&& (searchModel.KeyCountries == null || searchModel.KeyCountries.Contains(po.Parcel.City.Country))
&& (searchModel.KeyOrderStates == null || searchModel.KeyOrderStates.Contains(po.State.Value))
&& (searchModel.KeyFromDateRegisteredToOTS == null || po.DateRegisteredToOTS > searchModel.KeyFromDateRegisteredToOTS)
&& (searchModel.KeyToDateRegisteredToOTS == null || po.DateRegisteredToOTS < searchModel.KeyToDateRegisteredToOTS)
&& (searchModel.KeyFromDateDeliveredToVendor == null || po.DateRegisteredToVendor > searchModel.KeyFromDateDeliveredToVendor)
&& (searchModel.KeyToDateDeliveredToVendor == null || po.DateRegisteredToVendor < searchModel.KeyToDateDeliveredToVendor);
return expression;
}
public Func<ParcelOrder, bool> UserPrivilegeValdationExpression(string userId)
{
var roles = GetRolesForUser(userId);
Func<ParcelOrder, bool> expression =
po => po.ID == 1;
if (roles != null)
{
if (roles.Contains("ParcelAdministrator"))
expression =
po => true;
else if (roles.Contains("RegionalAdministrator"))
{
var user = db.AspNetUsers.First(u => u.Id == userId);
if (user.RegionalAdministrator != null)
{
expression =
po => po.HubID == user.RegionalAdministrator.HubID;
}
}
else if (roles.Contains("Customer"))
{
var customerID = db.AspNetUsers.First(u => u.Id == userId).CustomerID;
expression =
po => po.CustomerID == customerID;
}
else
{
expression =
po => false;
}
}
return expression;
}
If you can possibly avoid it, don't count for pagination. Just return the first page. It's always expensive to count and adds little to the user experience.
And in any case you're building the dynamic search wrong.
You're calling IEnumerable.Count(Func<ParcelOrder,bool>), which will force client-side evaluation where you should be calling IQueryable.Count(Expression<Func<ParcelOrder,bool>>). Here:
Func<ParcelOrder, bool> completeExpression = order => userPrivilegeValidation(order) && criteriaMatchValidation(order);
searchModel.PaginationTotalCount = db.ParcelOrder.Count(completeExpression);
But there's a simpler, better pattern for this in EF: just conditionally add criteria to your IQueryable.
eg put a method on your DbContext like this:
public IQueryable<ParcelOrder> SearchParcels(ParcelOrderSearchModel searchModel)
{
var q = this.ParcelOrders();
if (searchModel.KeyUploadID != null)
{
q = q.Where( po => po.UploadID == searchModel.KeyUploadID );
}
if (searchModel.KeyCustomerID != null)
{
q = q.Where( po.CustomerID == searchModel.KeyCustomerID );
}
//. . .
return q;
}
I have the following statement, and I want to modify it to not select all tables.
Exclude 2 columns customerItemNo and manufacturerItemNo in the if, and
Exclude 2 columns customerItemNoAppend and manufacturerItemNoAppend in the else if.
How can I do it?
if (p.UserInternal == 'Y' && p.UserActive == 'Y')
inventorySummary = DataProvider.SelectCondition<Q_TBL_INVENTORY_SUMMARY>
(r => r.InventoryLocationNo == location);
else if (p.UserInternal != 'Y' && p.UserActive == 'Y')
inventorySummary = DataProvider.SelectCondition<Q_TBL_INVENTORY_SUMMARY>
(r => r.InventoryLocationNo == location && (r.CustomerID == customerID || r.CustomerID == " "));
else
inventorySummary = new List<Q_TBL_INVENTORY_SUMMARY>();
i have attached object to context, despite i am getting the error Cannot remove an entity that has not been attached.
if (itemRemove != -1)
{
//var deleteDetails = DBContext.ProductCustomizationMasters.Where(p => p.ProductID == this.ProductID && p.CustomCategoryID == catId && p.CustomType == (short)catTypeId).Single();
var deleteDetails = DBContext.ProductCustomizationMasters.Single(p => p.ProductID == this.ProductID && p.CustomCategoryID == catId && p.CustomType == (short)catTypeId);
DBContext.ProductCustomizationMasters.Attach(deleteDetails);
DBContext.ProductCustomizationMasters.DeleteOnSubmit(deleteDetails);
RemoveCategoryItems(catId, catTypeId);
}
private void RemoveCategoryItems(int catId, CategoryType catTypeId)
{
switch (catTypeId)
{
case CategoryType.Topping:
(this.ToppingItems.Where(xx => xx.ToppingInfo.CatID == catId && xx.ProductID == this.ProductID).Single()).IsDefault = false;
FreeToppingItems.RemoveAll(x => x.ProductID == this.ProductID && x.ToppingInfo.CatID == catId);
break;
case CategoryType.Dressing:
(this.DressingItems.Where(xx => xx.DressingInfo.CatID == catId && xx.ProductID == this.ProductID).Single()).IsDefault = false;
FreeDressingItems.RemoveAll(x => x.ProductID == this.ProductID && x.DressingInfo.CatID == catId);
break;
case CategoryType.SpecialInstruction:
(this.InstructionItems.Where(xx => xx.InstructionInfo.CatID == catId && xx.ProductID == this.ProductID).Single()).IsDefault = false;
FreeInstructionItems.RemoveAll(x => x.ProductID == this.ProductID && x.InstructionInfo.CatID == catId);
break;
}
}
FIRST IDEA - You don't need to attach the item that you are going to delete. The item is already attached to the context and the state is being managed. Just skip the attach line and delete the object.
EDIT Since the attach doesn't appear to have been your problem, give this a shot:
if (itemRemove != -1)
{
var deleteDetails = DBContext.ProductCustomizationMasters.Single(p => p.ProductID == this.ProductID && p.CustomCategoryID == catId && p.CustomType == (short)catTypeId);
//Obviously, this isn't going to work directly, you need to actually assign the ID, Primary Key Field here...
var deleteMe = new ProductCustomizationMasters() { PrimaryKey = deleteDetails.PrimaryKey };
DBContext.Attach(deleteMe);
DBContext.DeleteOnSubmit(deleteMe);
DBContext.SubmitChanges();
RemoveCategoryItems(catId, catTypeId);
}
EDIT AGAIN - The code you have posted doesn't appear to be the source of your problem. There is something outside of this code that is setting an object up for deletion from the context ant has not been attached. I suggest working back through your code and inspecting all references to "DeleteOnSubmit" and making sure that those entities are attached when you mark them.