I am attempting to use the following code to do an update on a table with entity framework. The where statement will only work if I remove the and, either side of the and will bring results, but the and results in a null. I know that the value I am searching for exists.
foreach (fdd element in FddList)
{
var slist = context.ResidenceFDDs.ToList<ResidenceFDD>();
ResidenceFDD fddtoupdate = slist
.Where(s =>
s.StName.Contains("Adrienne") &&
s.StNum == element.addressnumb.ToString())
.FirstOrDefault<ResidenceFDD>();
fddtoupdate.Comments = "Comment newly added.";
context.SaveChanges();
}
if you are using .toString() then use as below
ResidenceFDD fddtoupdate = slist.Where(
s =>
s.StName.Contains("Adrienne") &&
s.StNum == element.addressnumb.ToString())
.FirstOrDefault<ResidenceFDD>().AsEnumerable();
Related
I am having two lists and filter based on a group of values.
var UserIdList = response.Users.Select(p => p.Id).ToList();
var filteredRecords =
(from o in om.Organizations join u in om.Users on o.Id equals u.OrganizationId where UserIdList.Contains(u.Id)
select new { Enabled = o.Enabled, Id = u.Id }).ToList();
Now i want to set 'Exists' property in 'response.Users' to true if 'Id' exists in filteredRecords.
Please let me know how can I set value with out using foreach loop.
I have tried with
response.Users.Where(x => x.Exists = (filteredRecords .Any(z => z.Id == x.Id))).ToList();
but could not succeed as it is giving only filter results.
I want full records which are matched and which are not
Linq doesn't really support update scenarios as it's for querying data.
For lists however there's a ForEach extension method:
UserList
.ToList()
.ForEach(item=> item.Exists = filteredRecords.Any(f=> f.Id == item.Id));
Is this clearer to read and easier to understand than a foreach loop...
Edit (after question updates)
// You can't use this... it won't even compile,
// x.Exists = ... is an assignment not a condition
response.Users.Where(x => x.Exists = (filteredRecords .Any(z => z.Id == x.Id))).ToList();
What you want to do is to work with a subset of users and update the values.
response
.Users
.Where(x=> filteredRecords.Any(z => z.Id == x.Id))
.ToList() // This materialises your IEnumerable/IQueryable to allow the ForEach extension method
.ForEach(x => x.Exists = true);
you could of course use:
var usersToEnable = response.Users.Where(x=> filteredRecords.Any(z => z.Id == x.Id);
foreach(var user in usersToEnable)
user.Enabled = true;
As a direct response to:
Please let me know how can I set value with out using foreach loop. I have tried with
response.Users.Where(x => x.Exists = (filteredRecords .Any(z => z.Id == x.Id))).ToList(); but could not succeed as it is giving only
filter results. I want full records which are matched and which are
not
What you've done there is selected a collection of response user items you wish to have Exists set to true.
Now you need to set that bool in this filtered collection, and then return the full response collection afterwards, instead of returning the filtered collection.
I think this is where you're getting confused.
I would like to select only the records that have the field "1" from the string eventTriggers (that looks something like this : "00100010" )
I've tried and succesfully done so with more than 1 calls .. but i doubt its efficient. Basically I would want something like this ... but apprently LINQ does not support this.
(LINQ to Entities does not recognize the method 'Char get_Chars(Int32)' method, and this method cannot be translated into a store expression.)
using (var service = new dB.Business.Service.BaseBusinessService<memo>())
{
List<memo> result = service.Repository.GetQuery().Where(p => p.ID == ID && p.eventTriggers[index] == '1').ToList();
}
Any hints towards the correct solution ? Thank you !
I Had the same problem and solved It with substring.
ervice.Repository.GetQuery().Where(p => p.ID == ID && p.eventTriggers.Substring(index,1) == "1").ToList();
EF can't convert the char array operation into a valid query. How about
IEnumerable<Memo> memos
using (var service = new dB.Business.Service.BaseBusinessService<Memo>())
{
memos = service.Repository.GetQuery()
.Where(p => p.ID == ID).AsEnumerable();
}
var result = memos.Where(m => m.eventTriggers[index] == '1').ToList();
This gets all the memos with a matching ID locally then filters on the eventTriggers array.
Alternatively you could convert eventTriggers into a numeric value and use a bit mask, this would probably be a much faster query.
Linq looking like this,
using (var service = new dB.Business.Service.BaseBusinessService<Memo>())
{
result = service.Repository.GetQuery()
.Where(p =>
p.ID == ID
&&
m.eventTriggers & mask != 0).ToList();
}
more exapmles here
Solved:
using (var service = new dB.Business.Service.BaseBusinessService<memo>())
{
List<memo> result = service.Repository.GetQuery().Where(p => p.ID == ID && p.eventTriggers.Contains('1')).ToList();
}
I am having an issue with getting linq to entities to perform well. The query I have (not mine, maintaining someone's code :-)), has several includes that I've determined are all necessary for the WPF screen that consumes the results of this query.
Now, the SQL generated executes very fast and only returns one row of data. But it is returning 570 columns, and i think the performance hit is in the overhead of creating all the objects and all of those fields.
I've tried using lazy loading, but that doesn't seem to have any effect on performance.
I've tried removing any of the "include" statements that aren't necessary, but it appears that they all are needed.
here's the linq query:
var myQuery =
from appt in ctx.Appointments
.Include("ScheduleColumnProfile")
.Include("EncounterReason")
.Include("Visit")
.Include("Visit.Patient")
.Include("Visit.Patient.PatientInsurances")
.Include("Visit.Patient.PatientInsurances.InsuranceType")
.Include("Visit.Patient.PatientInsurances.InsuranceCarrier")
.Include("MasterLookup")
.Include("User1")
.Include("User2")
.Include("Site")
.Include("Visit.Patient_CoPay")
.Include("Visit.Patient_CoPay.User")
.Include("Visit.VisitInstructions.InstructionSheet")
where appt.VisitId == visitId
&& appt.MasterLookup.LookupDescription.ToUpper() != Rescheduled
&& appt.Site.PracticeID == practiceId
&& appt.MasterLookup.LookupDescription.ToUpper() != Cancelled
orderby appt.AppointmentId descending
select appt;
The SQL generate is 4000 lines long with 570 columns in the select statment and 3 or 4 Union ALLs, so I'm not going to paste it here unless someone REALLY wants to see it. Basically, i'm looking for a way to get rid of the unions if possible, and trim down the columns to only what's needed.
Help!
:-)
if anyone is keeping track, this is the solution that ended up working for me. Thanks to everyone who commented and made suggestions... it eventually lead me to what i have below.
ctx.ContextOptions.LazyLoadingEnabled = true;
var myQuery =
from appt in ctx.Appointments
where appt.VisitId == visitId
&& appt.MasterLookup.LookupDescription.ToUpper() != Rescheduled
&& appt.Site.PracticeID == practiceId
&& appt.MasterLookup.LookupDescription.ToUpper() != Cancelled
orderby appt.AppointmentId descending
select appt;
var myAppt = myQuery.FirstOrDefault();
ctx.LoadProperty(myAppt, a => a.EncounterReason);
ctx.LoadProperty(myAppt, a => a.ScheduleColumnProfile);
ctx.LoadProperty(myAppt, a => a.Visit);
ctx.LoadProperty(myAppt, a => a.MasterLookup);
ctx.LoadProperty(myAppt, a => a.User1);
ctx.LoadProperty(myAppt, a => a.User2);
ctx.LoadProperty(myAppt, a => a.PatientReferredProvider);
var myVisit = myAppt.Visit;
ctx.LoadProperty(myVisit, v => v.Patient);
ctx.LoadProperty(myVisit, v => v.Patient_CoPay);
ctx.LoadProperty(myVisit, v => v.VisitInstructions);
ctx.LoadProperty(myVisit, v => v.EligibilityChecks);
var pat = myVisit.Patient;
ctx.LoadProperty(pat, p => p.PatientInsurances);
//load child insurances
foreach (PatientInsurance patIns in myAppt.Visit.Patient.PatientInsurances)
{
ctx.LoadProperty(patIns, p => p.InsuranceType);
ctx.LoadProperty(patIns, p => p.InsuranceCarrier);
}
//load child instruction sheets
foreach (VisitInstruction vi in myAppt.Visit.VisitInstructions)
{
ctx.LoadProperty(vi, i => i.InstructionSheet);
}
//load child copays
foreach (Patient_CoPay coPay in myAppt.Visit.Patient_CoPay)
{
ctx.LoadProperty(coPay, c => c.User);
}
//load child eligibility checks
foreach (EligibilityCheck ec in myAppt.Visit.EligibilityChecks)
{
ctx.LoadProperty(ec, e => ec.MasterLookup);
ctx.LoadProperty(ec, e => ec.EligibilityResponse);
}
I would recommend creating a new Class that contains only the properties that you need to display. When you project to a new type you don't need to have Include statements, but you can still access the navigation properties of the entity.
var myQuery = from appt in ctx.Appointments
where appt.VisitId == visitId
&& appt.MasterLookup.LookupDescription.ToUpper() != Rescheduled
&& appt.Site.PracticeID == practiceId
&& appt.MasterLookup.LookupDescription.ToUpper() != Cancelled
orderby appt.AppointmentId descending
select new DisplayClass
{
Property1 = appt.Prop1,
Proeprty2 = appt.Visit.Prop1,
.
.
.
};
If I want to iterate through a collection, and call a function on each element in the collection, I could go with :
foreach (var obj in objColl)
{
MyFunction(obj);
}
Should I want to do this with linq, I can use either of those :
//#1
var unused = (from var obj in objColl select MyFunction(obj)).ToList();
//#2
var unused = objColl.Select(obj => MyFunction(obj)).ToList();
I know this works, but it doesn't seem right. Of course, my actual cases are more complex queries that that, but it comes down to this since I could build my IQueryable with Linq and iterate through it and call the function.
Edit:
Here is one example of what I did. (Item# are things I can't disclose)
var dummyValue = (from
Item7 in dal.GetAgencyConvertions().Where(age => age.SourceName == "Item1" && age.TargetName == "Item2")
join Item6 in dal.GetAgencyConvertions().Where(age => age.SourceName == "Item2" && age.TargetName == "Item3") on Item6.TargetValue equals Item7.SourceValue
join agency in dal.GetAgencies() on Item7.SourceValue equals agency.Agency
orderby Item7.TargetValue
select vl.ValueListItems.Add(agency.ID, Item7.TargetValue)).ToList();
Go with the simple foreach, as you are clearly wanting to perform an action on (and/or using) the objects in your collection as opposed to wishing to project/filter/group/etc. the items in the sequence. LINQ is about the latter set of operations.
Edit: In the case of your update, I would simply create a query, and then iterate over the query in the foreach to perform the action.
var query = from Item7 in dal.GetAgencyConvertions().Where(age => age.SourceName == "Item1" && age.TargetName == "Item2")
join Item6 in dal.GetAgencyConvertions().Where(age => age.SourceName == "Item2" && age.TargetName == "Item3") on Item6.TargetValue equals Item7.SourceValue
join agency in dal.GetAgencies() on Item7.SourceValue equals agency.Agency
orderby Item7.TargetValue
select new { ID = agency.ID, Value = Item7.TargetValue };
foreach (var item in query)
vl.ValueListItems.Add(item.ID, item.Value);
To be frank, you have the same loop happening in your code, you merely mask it by using the ToList() extension method. As a byproduct, you are creating a list of values that you have no intention of using, while somewhat obfuscating the true intention of the code, all to save maybe a few characters.
Typically, a query shouldn't have any side effects (i.e. it shouldn't modify the state of the data or other data in your application) which raises the question, does MyFunction modify the state of your application? If it does, then you should use a foreach loop.
How about an Each() extension method?
public static void Each<T>(this IEnumerable<T> target, Action<T> action)
{
if (target == null) return;
foreach (T obj in target)
action(obj);
}
With Linq, can I use a conditional statement inside of a Where extension method?
var query = someList.Where(a => (someCondition)? a == "something" : true);
so, if 'someCondition' is false, 'Where' will be skipped.
Yes you can like:
var query = someList.Where(a => a == "something");
if (condition)
{
query = query.Where(b => b == "something else");
}
var result = query.ToList();
Because Where is producing an IQueryable, the execution is deferred until the ToList in my example so you can chain Wheres together as much as you want and then just execute it after you have passed all your conditions.
Make use of WhereIf extenstion method avaialbe in linq
Example
if (SearchControlMain.PostingID.HasValue)
query = query.Where(q => q.PostingID == SearchControlMain.PostingID);
instead of above go for the below
query = query.WhereIf(SearchControlMain.CategoryID.HasValue, q => q.CategoryID == SearchControlMain.CategoryID);
LINQ WhereIf Extension Method
LINQ to SQL Where Clause Optional Criteria
Not sure if this is appropriate but it is quite useful, you can use ifs quite handily with conditional where clauses:
var r = (from p in productinfo.tblproduct
where p.Accountid == accountid
select p);
if (uuf1 != null)
r = r.Where(p => p.UnitUserField1 == uuf1);
if (uuf2!= null)
r = r.Where(p => p.UnitUserField2 == uuf2);
So the where clause will be amended according to what is in UUF1 or UUF2 i.e. you might have only UUF1 with info, in which case it will take that and ignore the UUF2 where clause, you might have both in which it will take both or you might not have anything in UUF1 or 2 and your where clause will just take the accountid as the where clause.
In my case there were two "conditional" where depending on search keys, so I did:
var query = db.Package.Include("SomeThing")
.Where(item => searchString1 == null || searchString1 == "" || item.Contains(searchString1))
.Where(item => searchString2 == null || searchString2 == "" || item.Contains(searchString2));
...
from item in items
where condition1
&& (condition2 ? true : condition3)
select item
This is how can you can do it with the noob Linq syntax.
This applies the condition3 only if condition2 is false.
If condition2 is true, you are essentially doing && true which has no effect on the where clause.
So it is essentially doing this:
if(condition2)
{
from item in items
where condition1
select item
else
{
from item in items
where condition1
&& condition3
select item
}
I had a scenario like this where I had to check for null within the list itself. This is what I did.
items = from p in items
where p.property1 != null //Add other if conditions
select p;
// Use items the way you would use inside the if condition
But as Kelsey pointed out this would work too -
items = items.Where(a => a.property1 != null);
I'm not sure what the question is, but a possible answer could be:
Yes,
list.Where(item => { if (Foo(item)) return true; else return false; });
It would be a complicated way of saying something simple, though.
In my case, I wanted to keep the elements which met my criteria and log the ones that didn't without iterating multiple times.
var merchantsWithLocations = allMerchants.Where(m =>
{
if (m.Locations?.Any() != true)
{
_logger.Log("Merchant {merchantId} has no locations", m.Id);
return false;
}
return true;
};
Any time you want to do a side-effect per element (such as logging), breaking out the lambda into a statement body makes it easy to reason about.