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Get common records from list of list in linq

I have a list contains another list where I supposed to get the common elements.
Class model:
PlanInfo has shiftName, ilist of Plan.
Plan has start time, end time
public class Plan
{
public int Start { get; set; }
public int End { get; set; }
}
public class PlanInfo
{
public string ShiftName { get; set; }
public IList<Plan> lstPlan { get; set; }
}
iList of PlanInfo contains
[“shift1”, [1000,1200]],
[“shift2”,[1000,1100]],
[“shift3”,[1000,1200]]
Expected output in this should be empty since 1000,1200 doesn’t exist in shift2
[“shift1”, [1000,1200]],
[“shift2”,[[1000,1200],[1000,1100]],
[“shift3”,[1000,1200]]
Should return [1000,1200] since it’s common in all lists.
I tried using intersect, but here IList<PlanInfo is not fixed length. it could have more than one records.
Kindly suggest me which LINQ query serve the above result

Hmm, If I understand the requirements: Given a list of PlanInfo, find any Plans common to all PlanInfo...
var totalPlanInfos = planInfos.Count();
var commonPlans = planInfos
.SelectMany(x => x.Plans
.Select(p => new { x.ShiftName, Plan = p }))
.GroupBy(x => x.Plan)
.Where(x => x.Count() == totalPlanInfos)
.Select(x => x.Key)
.ToList();
This assumes that a Plan can only be counted once within a PlanInfo. (No duplicate plans) This also assumes that the plan info references for the same start/end times are pointing to the same object instance. If not, then you cannot group on the Plan, you will need a unique key (Like a plan ID) to group on. If these are EF entities pulled from a DbContext then they will be the same reference.
First get the total # of plan infos. In your example this would return 3.
Next, for all plan infos, use SelectMany to fetch the Plans, but compose that down into the PlanInfo.ShiftName + the Plan. This flattens your one to many. Next group by the Plan so that we can count the # of PlanInfos that each Plan appears in. Any/all counts that match the total number of PlanInfos means a Plan that appears in all PlanInfos, Select the Key to get that grouped Plan(s) and that should have it.
Edit: adding an example...
[Test]
public void TestPlanCheck()
{
var plan1 = new Plan { Start = 1, End = 2 };
var plan2 = new Plan { Start = 2, End = 3 };
var plan3 = new Plan { Start = 3, End = 4 };
var planInfos = new List<PlanInfo>
{
new PlanInfo{ Name = "Test1", Plans = new []{ plan1, plan2}.ToList() },
new PlanInfo{Name = "Test2", Plans = new []{plan2, plan3}.ToList()},
new PlanInfo{Name = "Test3", Plans = new []{ plan3, plan2}.ToList() }
};
var totalPlanInfos = planInfos.Count();
var commonPlans = planInfos
.SelectMany(x => x.Plans
.Select(p => new { x.Name, Plan = p }))
.GroupBy(x => x.Plan)
.Where(x => x.Count() == totalPlanInfos)
.Select(x => x.Key)
.ToList();
}
private class Plan
{
public int Start { get; set; }
public int End { get; set; }
}
private class PlanInfo
{
public string Name { get; set; }
public List<Plan> Plans { get; set; }
}
That was the test I had run using these stub classes. In this case the test will return back 1 match, for the Plan 2 value.
To outline the issue with ensuring plan references for the same start/end times match: If the setup looked like this:
[Test]
public void TestPlanCheck()
{
var plan1 = new Plan { Start = 1, End = 2 };
var plan2A = new Plan { Start = 2, End = 3 };
var plan2B = new Plan { Start = 2, End = 3 };
var plan3 = new Plan { Start = 3, End = 4 };
var planInfos = new List<PlanInfo>
{
new PlanInfo{ Name = "Test1", Plans = new []{ plan1, plan2A}.ToList() },
new PlanInfo{Name = "Test2", Plans = new []{plan2B, plan3}.ToList()},
new PlanInfo{Name = "Test3", Plans = new []{ plan3, plan2B}.ToList() }
};
var totalPlanInfos = planInfos.Count();
var commonPlans = planInfos
.SelectMany(x => x.Plans
.Select(p => new { x.Name, Plan = p }))
.GroupBy(x => x.Plan)
.Where(x => x.Count() == totalPlanInfos)
.Select(x => x.Key)
.ToList();
}
In this case even though plan 2A and 2B have the same start/end time, the group by would not group them together because they represent 2 references to 2 objects. This though would be fine:
var plan2A = new Plan { Start = 2, End = 3 };
var plan2B = plan2A;
Both point to the same reference. If you do have different references for the same plan ranges, you would need a planID then group on a PlanId. Ideally though I would check why the references don't match because they should to avoid potential errors based on assumptions of equality.

One can use Aggregate with Intersect on PlanInfo.Plans like:
var plansCommon = planInfoList.Select(p => p.Plans)
.Aggregate<IEnumerable<Plan>>((p1, p2) =>
p1.Intersect(p2, new PlanComparer()))
.ToList();
// Implement IEqualityComparer
class PlanComparer : IEqualityComparer<Plan>
{
public bool Equals(Plan x, Plan y)
{
if (x.Start == y.Start &&
x.End == y.End)
return true;
return false;
}
public int GetHashCode(Plan obj)
{
return obj.Start.GetHashCode() ^ obj.End.GetHashCode();
}
}
The Intersect will recursively apply on Plans list of each PlanInfo to provide list of Plan common across all.

Filtering from list of C# or LINQ

I am trying to filter from attachList the taxheaderID, it comes from my database which is structured as such.
public int attachmentID { get; set; }
public int headerID { get; set; }
public string uploadedfilename { get; set; }
public string originalfilename { get; set; }
public string foldername { get; set; }
Here is the code that gets data from the database:
public JsonResult GetAllAttach()
{
using (car_monitoringEntities contextObj = new car_monitoringEntities())
{
var attachList = contextObj.car_taxcomputationattachment.ToList();
return Json(attachList, JsonRequestBehavior.AllowGet);
}
}
These are my attempts:
attachList
.Select(x => x.headerID)
.Where(x => x == x)
.Take(1);
and:
attachList = attachList
.Where(al => attachList
.Any(alx => al.taxheaderID == alx.headerID
&& al.headerID == alx.headerID));
The problem is I want to parse multiple attach on a single headerID or filter them base on headerID. For example:
Problem to fix:
This is the table
Desired output:
Combined
data table:
data table
data table 2
Here is the actual solution that was made to get the output, but my coworker told me that it is not a good practice that's why I'm trying to filter it in the function itself. apologies for the trouble, thanks!
<div ng-repeat="att in attach|filter:{headerID:header.headerID}:true">
{{att.uploadedfilename}} <br />
</div>

To get attachments by Id
public JsonResult GetAllAttach(int headerId)
{
using (car_monitoringEntities contextObj = new car_monitoringEntities())
{
var attachList = contextObj.car_taxcomputationattachment
.Where(x => x.headerID == headerId)
.ToList();
return Json(attachList, JsonRequestBehavior.AllowGet);
}
}
If you want to have all data in one JSON result, then you need to create a nested view model.

Assuming you have the header id on which you want to filter in a local variable, you are almost correct
int headerIdToFind = 19;
// think of x as a local variable inside a foreach loop which
// iterates over each item in the attachList (it does not exist
// outside the where method)
// this is what you got wrong when you compared the item to itself
var filteredAttach = attachList.Where(x => x.headerId = headerIdToFind);
// if you want to select only some properties based on header id
// you can use select to project those properties
var filteredAttach = attachList.Where(x => x.headerId = headerIdToFind).
Select(x => new {x.attachmentId, x.folderName});
// based on last image, you only want to select (project) header id and the
// filename. so you do not need where (filter) at all
// you can put all the properties you need in the select clause
var filteredAttach = attachList.Select(x => new {x.headerId, x.attachmentId});
// you can enumerate the filtered attach list of convert it into a list
var filteredAttach = filteredAttach.ToList();

get collection with where clause as collection in Linq

Here is my service method:
public List<RelatedInvoiceData> GetRelatedInvoices(InvoiceSearch invoiceSearchFilters)
{
List<InvoiceInfoView> invoices = _wiseStepDbContext.InvoiceInfoView.Where(i => i.RecruiterCompanyId == _securityManager.CurrentRecruiterCompanyId).ToList();
List<RelatedInvoiceData> relatedInvoiceViewCollection = GetRelatedInvoiceCollection(invoices);
if (invoiceSearchFilters.CustomerId > 0)
{
relatedInvoiceViewCollection = relatedInvoiceViewCollection.Where(i => i.CustomerId == invoiceSearchFilters.CustomerId).ToList();
}
if (invoiceSearchFilters.VendorId > 0)
{
relatedInvoiceViewCollection = relatedInvoiceViewCollection.Where(i => i.VendorId == invoiceSearchFilters.VendorId).ToList();
}
return relatedInvoiceViewCollection;
}
here is my filterObject :
public class InvoiceSearch
{
public int[] CustomerId { get; set; }
public int[] VendorId { get; set; }
}
Previously I used where in linq for single customer Id now i want filter with multiple customerIds and multiple VendorIds.
Now I want to go with array of CustomerIds. How to write LINQ for Array in Where clause. Thanks for any help

If I understand correctly, you mean that i.CustomerId is now an array or List<>. If that's the case, then you can use the.Contains() method. Something like this should do what you want: relatedInvoiceViewCollection = relatedInvoiceViewCollection.Where(i => i.CustomerId.Contains(invoiceSearchFilters.CustomerId)).ToList();
Edit: This question may be helpful if you want to check for intersections in two arrays, which you can do in your case like this:relatedInvoiceViewCollection = relatedInvoiceViewCollection.Where(i => i.CustomerId.Intersect(invoiceSearchFilters.CustomerId).Any()).ToList();

relatedInvoiceViewCollection.Where(x => relatedInvoiceViewCollection.Contains(invoiceSearchFilters.CustomerId)).ToList();
or
relatedInvoiceViewCollection.Where(x => x.Contains(invoiceSearchFilters.CustomerId)).ToList();

How do I count the number of child collection's items using LINQ Method Syntax?

Let's say I have a schema, representing Question entities. Each question can be voted up, voted down or, of course, not voted at all - just like here in StackOverflow. I want to get the number of voteups for a given user.
int number = (from q in userDbContext.Questions
from qv in q.QuestionVotes
where qv.IsVoteUp
select qv).Count();
I want to write the same query, but using Method Syntax. How do I do this with the same example?

You can use SelectMany:
userDbContext.Questions.SelectMany(x => x.QuestionVotes).Count(x => x.IsVoteUp);

This LINQ query demonstrates how to do that using 3 level structure tree > branch > leaf as an example.
So the code below gives you the number of the leaves from all branches of all trees (all or only colored with the given color):
public class Calculator
{
public int CountAllLeafsOn(List<Tree> trees, string сolor = null)
{
// Count the leafs (all from all branches of all trees, or only if they are colored with the provided color)
return сolor == null
? trees.Sum(tree => tree.Branches.Sum(branch => branch.Leaves.Count))
: trees.Sum(tree => tree.Branches.Sum(branch => branch.Leaves.Count(leaf => leaf.Color.Equals(сolor))));
}
}
public class Tree
{
public List<Branch> Branches { get; set; }
}
public class Branch
{
public List<Leaf> Leaves { get; set; }
}
public class Leaf
{
public string Color { get; set; }
}
Hope that helps.

It must work:
int number = userDbContext.Questions
.Select(x => x.QuestionVotes.Count(y => y.IsVoteUp))
.Sum();
It will get the count of filtered child items for each parent. Then Sum() will compute the sum of these values.

You can count children using Where like this:
foreach (YourCollectionType item in datagrid.Items)
{
var children = datagrid.ItemsSource.OfType<YourCollectionType>().Where(x => x.Item1 == item.Item1 && x.Item2 == item.Item2 && x.Item3 == item.Item3 && x.Item4 == item.Item4);
item.Results = children.Count();
Trace.TraceInformation(item.Results.ToString());
}

c# Searching List<t> inside another List<T>

How would I search for a value within a List<t> inside another List<t>
i.e.
//FooInner Class
public class FooInner {
public int FooInnerId { get; set; }
public String FooValue { get; set; }
}
//FooOuter Class
public class FooOuter {
public int FooOuterId { get; set; }
public List<FooInner> FooInnerCollection { get; set; }
}
If I just wanted to find a value in the outer class
// Working code
List<FooOuter> fooOuterCollection = GetSomeData();
var tmp = fooOuterCollection.Find( f => f.FooOuterId == 2 );
But what if I wanted the FooInner Object where FooOuterId == 2 and FooInnerCollection.FooInnerId == 4 (or contains depending how you look at it).
Hopefully that makes sense.

fooOuterCollection
.Where(outer => outer.FooOuterID == 2)
.SelectMany(outer => outer.FooInnerCollection)
.FirstOrDefault(fooInner => fooInner.FooInnerId == 4);
First we filter the outer objects to only include those with Id == 2
Then we use SelectMany to flatten out the multiple InnerCollections that we may find
Finally we filter based on the inner Id == 4

You can get inner object like this-
var temp= fooOuterCollection.Where(f => f.FooOuterId == 2)
.SelectMany(f => f.FooInnerCollection)
.FirstOrDefault(fi => fi.FooInnerId == 4));
If you need outer object, you need to use Any() extension method to see if inner list contains required element -
var temp = fooOuterCollection.FirstOrDefault(f => f.FooOuterId == 2 &&
f.FooInnerCollection.Any(fi => fi.FooInnerId == 4);

You could just use LINQ's query syntax:
var results = from o in outerList
where o.FooOuterId == 2
from i in o.FooInnerCollection
where i.FooInnerId == 4
select i;