Description

Abhi (abhisheksinha89)

opened on Mar 21, 2018

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Steps to reproduce

Create a simple cmdlet with this method as the ProcessRecord()

protected override void ProcessRecord()
{
        DataTable dt = new DataTable("test");
        dt.Columns.Add("Name", typeof(string));
        dt.Columns.Add("Age", typeof(string));
        DataRow dr = dt.NewRow(); dr["Name"] = "John"; dr["Age"] = "20";
        DataRow dr2 = dt.NewRow(); dr["Name"] = "Susan"; dr["Age"] = "25";
        dt.Rows.Add(dr); dt.Rows.Add(dr2);
        WriteObject(dt, enumerateCollection: true);
}

Expected behavior

Return type should be a System.Array with the 2 rows enumerated.
(This works on Powershell 5 with the full .NET Framework)

Actual behavior

Return type is a DataTable not a System.Array with the rows enumerated.

Environment data

> $PSVersionTable

Activity

1. mklement0 commented on Mar 21, 2018

   

   Michael Klement (mklement0)

   on Mar 21, 2018

   Contributor

   More actions

   At least at first glance the current behavior makes more sense, given that [System.Data.DataTable] does not implement the [System.Collections.IEnumerable] interface and PowerShell therefore doesn't consider it a collection.

   That the behavior changed is definitely disconcerting, however, and I hope someone else can shed light on this.

   Using WriteObject(dt.Rows, enumerateCollection: true) instead fixes the problem (because the type of .Rows is [System.Data.DataRowCollection], which does implement [IEnumerable])
2. BrucePay commented on Mar 21, 2018

   

   Bruce Payette (BrucePay)

   on Mar 21, 2018

   Collaborator

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   The issue is here in the code:
   

   PowerShell/src/System.Management.Automation/engine/LanguagePrimitives.cs

   Line 479 in 41b3161

   #if !CORECLR

   
   Enumerating DataTables is explicitly disabled .

   #if !CORECLR
               if (typeof(DataTable).IsAssignableFrom(objectType))
               {
                   return LanguagePrimitives.DataTableEnumerable;
               }
   #endif
   

   I don't know why this was done or if there is any reason not to turn it back on (other than it's a breaking change from 6.0). I've marked it for review by the committee.

   Reacted by Michael Klement
3. Bruce Payette (BrucePay)

   added

   WG-Enginecore PowerShell engine, interpreter, and runtimecore PowerShell engine, interpreter, and runtime

   Issue-Discussionthe issue may not have a clear classification yet. The issue may generate an RFC or may be reclassifthe issue may not have a clear classification yet. The issue may generate an RFC or may be reclassif

   Review - CommitteeThe PR/Issue needs a review from the PowerShell CommitteeThe PR/Issue needs a review from the PowerShell Committee

   on Mar 21, 2018
4. daxian-dbw commented on Mar 21, 2018

   

   Dongbo Wang (daxian-dbw)

   on Mar 21, 2018

   Member

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   I think the code was if/def'ed out originally when DataTable is not available in .NET Core.
5. Steve Lee (SteveL-MSFT)

   added

   Committee-ReviewedPS-Committee has reviewed this and made a decisionPS-Committee has reviewed this and made a decision

   and removed

   Review - CommitteeThe PR/Issue needs a review from the PowerShell CommitteeThe PR/Issue needs a review from the PowerShell Committee

   on Mar 28, 2018
6. SteveL-MSFT commented on Mar 28, 2018

   

   Steve Lee (SteveL-MSFT)

   on Mar 28, 2018

   Member

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   @PowerShell/powershell-committee reviewed this and it makes sense to have it consistent in that datarows are enumerated
7. Aditya Patwardhan (adityapatwardhan)

   closed this as completedin #6511on Mar 29, 2018
8. Ilya (iSazonov)

   added

   Resolution-FixedThe issue is fixed.The issue is fixed.

   on Mar 30, 2018
9. Matteo-T commented on Oct 31, 2022

   

   Matteo Taveggia (Matteo-T)

   on Oct 31, 2022

   More actions

   FWIW, there is a typo in Abhi (@abhisheksinha89)'s repro:

       // ...
       DataRow dr2 = dt.NewRow(); dr2["Name"] = "Susan"; dr2["Age"] = "25";   // dr2, instead of dr!
       // ...

   which would make it look like this was not fixed :-)

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