Bug 16530 - Bug in LINQ Join over IEnumerable data when both rows have a "null" key
Summary: Bug in LINQ Join over IEnumerable data when both rows have a "null" key
Status: RESOLVED FIXED
Alias: None
Product: Class Libraries
Classification: Mono
Component: System.Core ()
Version: 3.2.x
Hardware: PC All
: --- normal
Target Milestone: Untriaged
Assignee: Marek Safar
URL:
Depends on:
Blocks:
 
Reported: 2013-11-30 10:55 UTC by donsyme
Modified: 2013-12-02 13:07 UTC (History)
2 users (show)

Tags:
Is this bug a regression?: ---
Last known good build:

Notice (2018-05-24): bugzilla.xamarin.com is now in read-only mode.

Please join us on Visual Studio Developer Community and in the Xamarin and Mono organizations on GitHub to continue tracking issues. Bugzilla will remain available for reference in read-only mode. We will continue to work on open Bugzilla bugs, copy them to the new locations as needed for follow-up, and add the new items under Related Links.

Our sincere thanks to everyone who has contributed on this bug tracker over the years. Thanks also for your understanding as we make these adjustments and improvements for the future.


Please create a new report on GitHub or Developer Community with your current version information, steps to reproduce, and relevant error messages or log files if you are hitting an issue that looks similar to this resolved bug and you do not yet see a matching new report.

Related Links:
Status:
RESOLVED FIXED

Description donsyme 2013-11-30 10:55:12 UTC
This is a bug in the Mono Join method implementation for IEnumerables when used with Nullables. Joins are happening for rows where both columns have "null", this is a mistake. This is still present in 3.2.5.

F# repro below (there will be a C# repro too). .NET gives the right results.

GroupJoin should also be checked.

------


open System
open System.Linq

type Customer(name:string, cost:float, quantity:Nullable<int>) = 
    member x.Name = name
    member x.Cost = cost
    member x.Quantity = quantity

let c1 = Customer( name="Don", cost=6.2, quantity=Nullable())
let c2 = Customer( name="Peter", cost=4.2, quantity=Nullable(10))

let db = [c1;c2]

db.Join(db,(fun i -> i.Quantity),(fun i -> i.Quantity),(fun i j -> (i.Cost, j.Cost))).ToArray()
// expect [(4.2, 4.2)]
// get  [(6.2, 6.2); (4.2, 4.2)]
Comment 1 Marek Safar 2013-12-02 13:07:53 UTC
Fixed in master