All Questions
64
questions
100
votes
1
answer
90k
views
Cannot use a lambda expression as an argument to a dynamically dispatched operation without first casting it to a delegate or expression tree type
I am working with .NET4.5 and VS2013, I have this query that gets dynamic result from db.
dynamic topAgents = this._dataContext.Sql(
"select t.create_user_id as \"User\", sum(t.netamount) as \"...
- 59.6k
19
votes
5
answers
344
views
Is there an elegant LINQ solution for SomeButNotAll()?
Here is what I'm trying to do overall. Just to be clear, this isn't homework or for a contest or anything. Hopefully, I've made the wording clear enough:
Problem
Given a set of strings in the same ...
- 61.3k
17
votes
2
answers
16k
views
When to use LINQ's .ToList() or .ToArray()
After running this code:
var input = new List<T>( ... );
var result = input.Select( t => new U(t) );
U first1 = null;
foreach ( U u1 in result )
if ( first1 == null )
first1 = ...
- 4,508
11
votes
4
answers
3k
views
Execution-Deferred IQueryable<T> from Dynamic Linq?
I am using Dynamic Linq to perform some queries (sorry but it's my only option). As a result, I am getting an IQueryable instead of an IQueryable<T>. In my case, I want an IQueryable<Thing>...
- 13.2k
8
votes
2
answers
3k
views
DbGeometry makevalid?
I'm new to this. I don't know how to use the SqlSpatialFunction MakeValid.
I have a DbGeometry which is a polygon. This polygon is not valid and I want to
make it valid.
Can anyone explain how to use ...
- 3,912
5
votes
1
answer
3k
views
Comparing two collections with IEquatable while using only LINQ
This question is for educational purposes only and I can solve it easily by using for loop that returns false on first mismatch.
I am implementing IEquatable<CustomerFeedbackViewModel> on ...
- 59.6k
5
votes
3
answers
10k
views
Combine two lists into one based on property
I would like to ask whether there's an elegant and efficient way to merge two lists of MyClass into one?
MyClass looks like this:
ID: int
Name: string
ExtID: int?
and the lists are populated from ...
- 1,072
3
votes
2
answers
2k
views
Split a List of an Object group by some properties with lambda expression
This is My Type:
public class MyObj {
public long Number { get; set; }
public string Name { get; set; }
public string Message { get; set; }
public DateTime RegisterDate { get; set; }
}...
- 13.4k
3
votes
2
answers
1k
views
Linq's Enumerable.Count method checks for ICollection<> but not for IReadOnlyCollection<>
Background:
Linq-To-Objects has the extension method Count() (the overload not taking a predicate). Of course sometimes when a method requires only an IEnumerable<out T> (to do Linq), we will ...
- 61.1k
3
votes
1
answer
1k
views
Adding a character at the beginning of a string if it does not exist using LINQ
I have a string which I apply some LINQ methods. After applying a Replace, I would like to add a '/' character at the beginning of the resulting string if and only if it does not exists yet.
For ...
- 10.2k
3
votes
2
answers
1k
views
Create a parent -> children hierarchy from two collections
I have two separate collections instances filled with data
List<Parent> parents;
List<Child> children;
two collections can be connected through Child.ParentId, and Parent.Children.
...
- 6,398
3
votes
0
answers
693
views
MVC view compilation using wrong .NET Framework
An existing web application is using .NET Framework 4.5.1.
The project has the setting MvcBuildViews set to true.
The project also uses a Prepend extension method for IEnumerable<T>.
Stuff ...
- 1,091
2
votes
2
answers
5k
views
convert foreach to linq expression
I have the following code which transforms a List of myCar objects to an Array of Car objects from a third-party web service so I can then pass the cars to the 3rd party web service:
var cars = new ...
- 3,971
2
votes
2
answers
71
views
Linq Any() times out
I am trying to compare two data tables using Linq. Very simple tables, just one column but have about 44,000 rows. I use the following but when I trace it, when it gets to if (dr.Any()), it just sits ...
- 2,108
2
votes
3
answers
364
views
Failure to implicitly convert class to base class when using LINQ IEnumerable.ToDictionary()
I have the following situation which is confusing me.
Given:
public class ThermoRawFile : MsDataFile { }
public abstract class MSDataFile { }
I am unable to run this LINQ IEnumerable.ToDictionary()...
- 3,501
2
votes
5
answers
3k
views
Using C# LINQ to concat a filtered List<object> to List<string>
This is probably easy for someone more experienced with LINQ and the Lambda expressions in C#. I'm just starting out with them, so I must be missing something.
I have a custom object like this:
...
- 16.9k
2
votes
1
answer
542
views
Translating WITH ROLLUP SQL statement to LINQ
I need a help to translate a statement from LINQ to SQL
SQL
SELECT MONTH(ind_receita.lad_ins_date) as 'Month', SUM(ind_receita.valor) as Monthly_Value
FROM ind_receita
WHERE YEAR(ind_receita....
- 4,668
2
votes
2
answers
227
views
How to sort IEnumerable with limited result count? (another implementation of .OrderBy.Take)
I have a binary file which contains more than 100 millions of objects and I read the file using BinaryReader and return (Yield) the object (File reader and IEnumerable implementation is here: ...
- 1,672
1
vote
2
answers
2k
views
Get the Substrings within the List<string> collection using Linq
I've a collection list.
List<string> mycollections = new List<string>(new string[]
{
"MyImages/Temp/bus.jpg",
"MyImages/Temp/car.jpg",
...
- 5,678
1
vote
1
answer
62
views
Compile a list of unique objects using LINQ
Having the pseudo code
class Bar {int BarId;}
class Foo {
List<Bar> Bars;
}
Using Linq, how should I select all avaiable unique bars from the foo list ?
List<Foo> foos = GetFoos(); //...
- 14.6k
1
vote
1
answer
723
views
Inheritance and Polymorphism in LINQ Lambdas
I've got a couple of classes inheriting from a base class
Public MustInherit Class BaseClass
Public Property Name as String
End Class
Public MustInherit Class ClassA
Inherits BaseClass
...
- 26.5k
1
vote
1
answer
1k
views
Cannot implicitly convert type 'System.Linq.IQueryable' to 'System.Data.Entity.Infrastructure.DbQuery'
I receive this error when I put the following code:
var rec = (bNoTracking ? tblOrders.AsNoTracking() : tblOrders);
...
...
...
//error on next line: Cannot implicitly convert type 'System.Linq....
- 1,866
1
vote
3
answers
272
views
How to join two tables with null values in referenced fields
The table t1("PO1") and the t2("DTM") contains following values
Table t1
PO101(string) Loop_Id (Int)
Item_1 6
Item_2 8
---
Table t2
DTM02(string) Loop_Id(...
- 5,751
1
vote
1
answer
568
views
Linq Return grouped Table as Datatable
I wrote a function that returns a DataTable Object. For the following code
Public Function GetArtikelsAbove50(ByVal limit As Integer) As DataTable
Dim query = _Set.Ten_Most_Expensive_Products....
- 5,475
1
vote
0
answers
250
views
Ignore certain string in list of split string while splitting in c#
I need to split string in given lines based on list of string given. For this I use list of string to split line value and it works perfectly fine for most of the case but not for some of them.
As ...
- 123
1
vote
1
answer
60
views
Linq to Entities filtering out default parameters
Say I have the below method where the insuredNumber is required to be populated but the remaining three parameters may contain default values as below
Method Signature:
public List<...
- 6,456
1
vote
1
answer
1k
views
How can I invoke several clients' async methods and aggregate the results into one task generically?
The following code is intended to reduce redundant code by allowing you to generically invoke the same selector on a set of "getters" (data retrieval clients) and have all of the results combined. The ...
- 9,870
1
vote
1
answer
422
views
Resultant LinQ Query to a new DataTable
Refer to earlier post/Question:
LINQ to Swap few Columns to Rows of a DataTable using C#
I want the resultant of the query interms of a new dataTable directly instead of defining columns in the new ...
- 5,678
0
votes
3
answers
136
views
Linq Select that will generate tied scores for similar values
I'm trying to generate a simple league table with positional numbers based on scores.
e.g. Given the following
List<Player> players = new List<Player>() {
new Player { Name = "John", ...
- 43.9k
0
votes
4
answers
330
views
handling no result found
Following line throw exception if there is no matching record found.
Guid stuId= context.Students.FirstOrDefault(x => x.Name == student.Name).Id;
I understand, i can handle above line
var stuId=...
- 940
0
votes
4
answers
267
views
LINQ Replace Different String Values
I constructed a variable by parsing a text file with some addresses.
FileInfo fi = new FileInfo(@"C:\temp\Addresses.txt")
var ZipCodesAndCountryCodes = File.ReadLines(fi.FullName)
.Select(...
- 1,692
0
votes
3
answers
147
views
Using Anonymous method not preferred by .NET itself?
I am trying to learn the anonymous method and tried out this sample.
So, whenever I am trying to call WriteLog function i can just use
()=> { return "someLogData" };
The advantage is that, I ...
0
votes
2
answers
179
views
IEnumerable<> being skipped by foreach code; Converting IEnumerable<> to List<> doesnt return anything
Basically I have this code:
public static async Task<bool> SubmitOrdertoBroker(CASOrderModel order, IEnumerable<CASOrderItemModel> modelOrderItems)
{
ObservableCollection<...
- 877
0
votes
5
answers
4k
views
Using "contains" to query a list <Key-Value> in C#
In my code, I have "sourceElements" is a type of
List<KeyValuePair<string, string>>.
I need to query if the keys of this list contains a particular value and i tried this:
...
0
votes
1
answer
1k
views
Unable to use ICollection.ToList()
I am trying to call ToList() here:
using System.Collections.Generic;
using System.Collections.Specialized;
using System.Linq;
namespace CSVStuff
{
public static class CSVContentGenerator
{
...
- 9,136
0
votes
2
answers
187
views
Get records from Generic Object using LINQ C#
I have generic object and I need to get item {code, description} from it using LINQ Query
Class
[Serializable]
[XmlRoot("Genders")]
public class Gender
{
[XmlElement("Genders")]
public ...
- 5,393
0
votes
2
answers
2k
views
LINQ anonymous object is inaccessible due to its protection level
I have LINQ logic that collects regex parsed data into a dynamically-created dictionary. The issue I am facing is accessing the data in the dictionary (Info).
Regex
.Matches(text, pattern,
...
- 125
0
votes
1
answer
290
views
Observable.Create doesn't work and Observable.ToEnumerable blocks indefinitely
Why the code below doesn't work?
var observable = Observable.Create<int>(o => new Action(() =>
{
o.OnNext(0);
o.OnCompleted();
}));
foreach (var item in observable.ToEnumerable())...
- 25k
0
votes
1
answer
143
views
Dynamic LINQ statement
I am trying to query database using EF and LINQ. I have multiple queries to filter data based on user permissions with in the application.
from p in db.EmployeeDetails
join i in db.EmployeeDept on p....
- 718
0
votes
1
answer
93
views
How to iterate through a list and while iterating, iterate through another list and replace values for upper list with inner list key value pairs
Ok what i want is simple but i could not write it properly
I want to replace each value of a string list with multiple values (another list hold this values). I can write several loops however i want ...
- 23.4k
0
votes
2
answers
542
views
Linq results to a var does not populate values unless refreshed manually
I have this code fragment which returns specific records from a dataset.
DataTable tblr = new DataTable("itemsToValidate");
tblr.Columns.Add("Position", typeof(string));
tblr....
- 5,751
0
votes
1
answer
2k
views
Displaying multiple rows in a single View using Details Scaffolding [closed]
i have an employee details table, where i have a column called Role. Each employee can have more than one role. Currently following is the recordset that I am getting from SQL which i want to display ...
- 37
0
votes
1
answer
66
views
Tranform and Apply Expression via LINQ?
I am looking to support "expression passthru" as follows:
public IFastIndexingCollection<T> {
// Main data structure here =
// Key = property name
// Value = class below
private ...
- 6,547
0
votes
1
answer
88
views
Linq join and count gives me an error... don't know why c#
I'm using asp.net web forms 4.5
I'm trying to join two tables products and lots by
var query = _cc.products.Join(_db.lots,
p => p.parentLotIndex,
...
- 101
0
votes
1
answer
148
views
Which extension method is used when indexing into IEnumerable [duplicate]
When indexing into an IEnumerable, I've noticed that using an index that is out of range will result in a default value being returned. I would have expected to receive an ArgumentOutOfRangeException. ...
- 1,359
0
votes
2
answers
80
views
complicated mvc linq generated sql script
I am pretty new to MVC world, but I been doing asp.net for years now. I started this project with mvc so I can get used to it. I been struggling some overly complicated sql statements linq has been ...
- 317
0
votes
1
answer
1k
views
Index (zero based) must be greater than or equal to zero and less than the size of the argument list in ef 5.0 query
I have code-first based context with following entities:
public class City : IEquatable<City>
{
public City()
{
Posts = new List<Post>();
}
public City(string ...
- 901
0
votes
2
answers
1k
views
LINQ to Swap few Columns to Rows of a DataTable using C#
I've datatable:
location Quarter ppl_required ppl_available
BLR Q1 70 35
BLR Q2 50 45
BLR Q3 25 28
BLR ...
- 5,678
0
votes
0
answers
36
views
How to modify treeBuilder.Dot to generate LEFT JOIN instead of INNER JOIN in custom function generator for NHibernate?
Im trying to extend LINQ to NHibernate provider for my custom function. The problem that I found is that, whenever I try to access a FK from my entity, it generates a "INNER JOIN" statement, ...
- 9
0
votes
1
answer
79
views
Pick elements from list based on a selection criteria which involves previously selected element
I have a list with numbers which are actually distances, say 0.4,1.2, 5.6,7.8,8.9,10.2, ..... 10000.25.
Now I would like to select every element from this list such that the distance between each ...
- 347