We Keep Coding

Update IQueryable result before using as join in next query

I need to use Linq to Entity Framework to query a LOCATION table to get the record of the location code with the MAX effective date, then use that result as a join in the next query.
I BELIEVE I need to do convert before the IQueryable is used, because I have that last clause in the second query where I want to exclude records where the FLOOR code is in the excludedSchools list. That excludedSchools list will have the newLocationCode in it.
So, I need to update the values in the IQueryable result before I use it. Can I do this? Here is my code:
using (var db = new TheContext())
{
IQueryable<LocationTable> locatinWithMaxEffDate =
(from lc in db.LocationTable
where lc.EFF_STATUS == "A" && lc.EFFDT <= DateTime.Now
group lc by lc.LOCATION into g
select g.OrderByDescending(x => x.EFFDT).FirstOrDefault()
);
foreach (var location in locatinWithMaxEffDate.ToList())
{
string newLocationCode;
if(codeMappingDictionary.TryGetValue(location.FLOOR, out newLocationCode))
{
// how do I update locatinWithMaxEffDate FLOOR value
// with newLocationCode so it works in the query below?
location.FLOOR = newLocationCode;
}
}
var query =
(from fim in db.PS_PPS_FIM_EE_DATA
join mloc in locatinWithMaxEffDate on fim.LOCATION equals mloc.LOCATION
where
fim.EMPL_STATUS == PsPpsFimEeData.EmployeeStatusValues.Active
&& fim.AUTO_UPDATE == PsPpsFimEeData.AutoUpdateValues.Enabled
&& includeJobCodes.Contains(fim.JOBCODE)
&& !excludedSchools.Contains(mloc.FLOOR)
select new PpsAdministratorResult
{
SchoolId = mloc.FLOOR,
Login = fim.OPRID,
EmployeeId = fim.EMPLID,
}
With the code above, the locatinWithMaxEffDate does not have the updated FLOOR values. I can see why this is, but can't seem to fix it.
So far, I have tried introducing another list to ADD() the new location record to, then casting that as an IQueryable, but I get an error about primitive vs concrete types.

I decided to make things easier on myself. Since both sets of data are very small (fewer than 1000 records each) I call take the entire set of data as an annonymous type:
using (var db = new TheContext())
{
IQueryable<LocationTable> locatinWithMaxEffDate =
(from lc in db.LocationTable
where lc.EFF_STATUS == "A" && lc.EFFDT <= DateTime.Now
group lc by lc.LOCATION into g
select g.OrderByDescending(x => x.EFFDT).FirstOrDefault()
);
var query =
(from fim in db.PS_PPS_FIM_EE_DATA
join mloc in locatinWithMaxEffDate on fim.LOCATION equals mloc.LOCATION
where
fim.EMPL_STATUS == PsPpsFimEeData.EmployeeStatusValues.Active
&& fim.AUTO_UPDATE == PsPpsFimEeData.AutoUpdateValues.Enabled
&& includeJobCodes.Contains(fim.JOBCODE)
select new PpsAdministratorResult
{
SchoolId = mloc.FLOOR,
Login = fim.OPRID,
EmployeeId = fim.EMPLID,
}
}
Then, just work with the two objects:
List<PpsAdministratorResult> administratorList = new List<PpsAdministratorResult>();
foreach (var location in query.ToList())
{
string newLocationCode;
if(schoolCodeMappings.TryGetValue(location.SchoolId, out newLocationCode)) // && newLocationCode.Contains(location.LOCATION))
{
location.SchoolId = newLocationCode;
}
if( !excludedSchools.Contains(location.SchoolId) )
{
administratorList.Add(location);
}
}
Now, I have the list I want.

Moving a LINQ sub query to an extension method fails at runtime

I'm working out this LINQ query in LINQPad. I'm doing something like this:
var perms = (from x in db.TableName // etc
select new ProfilePermission
{ // etc
});
perms = perms.Concat(from x in db.TableName // etc
select new ProfilePermission
{ // etc
});
var results = (from pi in db.AnotherTable
where pi.IsActive
select new MyViewModel
{
KeyId = pi.Id,
Permissions = (from pm in perms
where pi.ChildId == pm.ChildId
select pm)
}
Using this sub query works. So, I figured, let's move it to an extension method. I tried doing this:
public static IQueryable<ProfilePermission> GetProfilePermissions
(
this IMkpContext db
)
{
var perms = (from x in db.TableName // etc
select new ProfilePermission
{ // etc
});
perms = perms.Concat(from x in db.TableName // etc
select new ProfilePermission
{ // etc
});
return perms;
}
var results = (from pi in db.AnotherTable
where pi.IsActive
select new MyViewModel
{
KeyId = pi.Id,
Permissions = (from pm in db.GetProfilePermissions()
where pi.ChildId == pm.ChildId
select pm)
}
Now I get a message:
NotSupportedException: LINQ to Entities does not recognize the method 'System.Linq.IQueryable`1[PublicationSystem.Model.ViewModels.ProfilePermission] GetProfilePermissions(PublicationSystem.Model.IMkpContext)' method, and this method cannot be translated into a store expression.
Why does the sub query work one way, and not the other? I thought that perms ended up as an IQueryable<> either way.

The difference is that at the place you've used the extension method, it's not executed, but becomes a part of another expression (Select in your case), i.e. is memorized as MethodCallExpression to a method that is not recognized by EF query provider.
If you indeed use the extension method in some top level query construct like Join or GroupJoin, it will work. Or if you can move the call outside the query and store the result into a variable.
For instance, in your case the following will work:
var results =
from pi in db.AnotherTable
where pi.IsActive
join pm in db.GetProfilePermissions() on pi.ChildId equals pm.ChildId into permissions
select new MyViewModel
{
KeyId = pi.Id,
Permissions = permissions
};
as well as this:
var permissions = db.GetProfilePermissions();
var results =
from pi in db.AnotherTable
where pi.IsActive
select new MyViewModel
{
KeyId = pi.Id,
Permissions = (from pm in permissions
where pi.ChildId == pm.ChildId
select pm)
};

ASP.Net MVC 5 Entity Framework Select Where In?

I have 3 tables Project, Province, ProjProvRel
In my project page when I add data I select multiple provinces for each project
means my Province is multi select dropdown list.
I insert data it is working I get the inserted Id and added to ProjProvRel with selected Ids of Province
Now In details view I want to display my data but I could not solve it.
here is my code:
// GET: Project/Details/5
public ActionResult Details(int? id)
{
if (id == null)
return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
var mydata = db.Projects.Find(id);
if (mydata == null)
{
return HttpNotFound();
}
var prov_id = from o in db.ProRel where o.ProjectId.Equals(id) select o.ProvinceIds;
foreach (var p_id in prov_id)
{
int[] PIds = new int[] {p_id};
}
var Prov= from c in db.Provinces where c.ID in pIds;
ViewBag.Province = Prov;
return View(mydata);
}
one problem is how can I select data from table based on where condition
var prov_id = from o in db.ProRel where o.ProjectId.Equals(id) select o.ProvinceIds;
is the above query correct ? I am new to ASP.Net MVC
also blow query is correct ?
var Prov= from c in db.Provinces where c.ID in pIds;
how can I select data from Table Province where province.ID in PIds

Get the rows from ProRel where the ProjectId matches with id:
var prov_ids = db.ProRel.Where(r => r.ProjectId == id).Select(r => r.ProvinceId);
Get the provinces that can be found from prov_id:
var provs = db.Provinces.Where(p => prov_id.Any(i => p.ID == i));
I hope you don't mind the lambda-style LINQ.
Also, I think you should consider your variable naming. For example, prov_id gives the idea of a single id and since you declared the type implicitly it is difficult to tell otherwise.

Reduce linq query for filtering

I have a view with 3 textboxes which bind to properties in the ViewModel SupplierName, Contact, Address and one button which bind to SearchCommand property in my ViewModel.
My requirement is to filter Supplier records based on the above properties. I used EntityFramework.
The user can enter any of the above textboxes which lead me to write 9 different queries.
For instance if the user inputs data only on the SupplierName textbox then I need to run one query with SupplierName as parameter. If the user enters SupplierName and Contact textboxes then I need to run another query. And so on.
Here is my code:
public IEnumerable<Model.Supplier> GetAllSuppliersBySearch(string nameMatch, string contactMatch, string phoneMatch)
{
if(nameMatch!=null)
{
var q = from f in Context.Suppliers
where f.SupplierName==nameMatch
select f;
}
else if(contactMatch!=null)
{
var q = from f in Context.Suppliers
where f.ContactName==contactMatch
select f;
}
else if(phoneMatch!=null)
{
var q = from f in Context.Suppliers
where f.ContactName==contactMatch
select f;
}
return q.AsEnumerable();
}
Instead of writing multiple queries, how to accomplish this with one query or in any optimized way?

Compose query with lambda syntax:
IQueryable<Supplier> query = Context.Suppliers;
if (!String.IsNullOrEmpty(nameMatch))
query = query.Where(s => s.SupplierName == nameMatch);
if (!String.IsNullOrEmpty(contactMatch))
query = query.Where(s => s.ContactName == contactMatch);
// etc
return query.AsEnumerable();
Another option is adding parameter-checking conditions to query
var query =
from s in Context.Suppliers
where (String.IsNullOrEmpty(nameMatch) || s.SupplierName == nameMatch) &&
(String.IsNullOrEmpty(contactMatch) || s.ContactName == contactMatch)
// etc
select s;

More efficient way of loading children of entity objects in linq to entity query

I have a rather complex linq to entity query that I'm performing, in the end, I have a result set. I loop through that result set, build business objects and return that list of business objects. it's pretty quick, the problem is that 2 of the child properties are complex objects with their own child objects. for every business object in my loop, I then have to make 2 DB calls to fill its child object. Those 2 calls slow down the overall process, is there a better way to do this? noob to EF here. (EF 4,SQL Server 2008,c#)
Get a result set:
var newresult = from r in result // result is another complex query
join subedit in
(from sa in context.Security_Access
join g in context.Security_UserGroup on sa.EntityID equals g.GroupID
where (sa.PrivledgeID == xx) && g.UserID == userId
select new { user = g.UserID, linkid = sa.LinkID }).Distinct() on new { aid = r.AssetId } equals new { aid = subedit.linkid } into theSubEdit
from subEditAccess in theSubEdit.DefaultIfEmpty()
join subdownload in
(from sa in context.Security_Access
join g in context.Security_UserGroup on sa.EntityID equals g.GroupID
where (sa.PrivledgeID == xx|| sa.PrivledgeID == yy) && g.UserID == userId
select new { user = g.UserID, linkid = sa.LinkID }).Distinct() on new { aid = r.AssetId } equals new { aid = subdownload.linkid } into theSubDownload
from subDownloadAccess in theSubDownload.DefaultIfEmpty()
join subView in
(from sa in context.Security_Access
join g in context.Security_UserGroup on sa.EntityID equals g.GroupID
where (sa.PrivledgeID == xx|| sa.PrivledgeID == yy|| sa.PrivledgeID == 101) && g.UserID == userId
select new { user = g.UserID, linkid = sa.LinkID }).Distinct() on new { aid = r.AssetId } equals new { aid = subView.linkid } into theSubView
from subViewAccess in theSubView.DefaultIfEmpty()
select new { r, EditAccess = (int?)subEditAccess.user, DownloadAccess = (int?)subDownloadAccess.user, ViewAccess = (int?)subViewAccess.user };
I then loop through that result set:
foreach (var asset in newresult)
{
// and build a new business object, set its properties
BoAsset boAsset = new BoAsset();
boAsset.HasEditRights = (asset.EditAccess > 0);
boAsset.HasDownloadRights = (asset.DownloadAccess > 0);
boAsset.HasViewRights = (asset.ViewAccess > 0);
boAsset.Description = asset.r.Description;
boAsset.DetailedDescription = asset.r.DetailedDescription;
boAsset.Keywords = asset.r.Keywords;
boAsset.Notes = asset.r.Notes;
boAsset.Photographer = asset.r.Photographer;
boAsset.PhotographerEmail = asset.r.PhotographerEmail;
boAsset.Notes = asset.r.Notes;
boAsset.Author = asset.r.Author;
// these 2 properties i've commented out are
// complex objects/entities, setting them the way I am
// requires me to call 2 separate methods which make 2 DB trips
// per business object.
//boAsset.Domains = GetAssetDomains(asset.r.AssetId);
//boAsset.DomainEntries = GetAssetCustomDomains(asset.r.AssetId);
myListofObjects.Add(boAsset);
}
return myListofObjects;
Is there a better way?

Just add this .Include("Domains").Include("DomainEntries") to your Linq in in context.Security_Access That should get rows from those tables all in one go.
So your "inner" queries would look like:
from sa in context.Security_Access.Include("Domains").Include("DomainEntries")
join g in context.Security_UserGroup on sa.EntityID equals g.GroupID
where (sa.PrivledgeID == xx) && g.UserID == userId
select new { ...
Here is the documentation from MS: http://msdn.microsoft.com/en-us/library/bb738708.aspx

If you want to improve your performance use compile queries !
You can check the example here.
static readonly Func<AdventureWorksEntities, Decimal,
IQueryable<SalesOrderHeader>> s_compiledQuery2 =
CompiledQuery.Compile<AdventureWorksEntities, Decimal, IQueryable<SalesOrderHeader>>((ctx, total) =>
from order in ctx.SalesOrderHeaders.Include("Orders") where order.TotalDue >= total select order);
MSDN
AND
You can Introduce Include suppose to select all the employees along with their departments . If you have a navigational property, you won't need a join at all. You can use Include like this:
List<Employee> employeesWithDepartments = CreateObjectSet<Employee>().
Include(e => e.Department).
ToList();