### The Problem:

In short, the problem occurs when the `MSDataSetGenerator` tool runs, but the `System.Data.DataSetExtensions` assembly has not yet been loaded into the current Visual Studio process.  

### The Solution: 

One way to load the assembly is just to open any XSD file and *THEN* re-generate the designer code.

The following steps should generate the appropriate designer file:

1. Open any XSD file to the designer view (this loads `DataSetExtensions.dll`)
2. Right Click on the XSD and Select `Run Custom Tool`

**Here's a full [step by step walkthrough with pictures of the issue and solution][walkthrough]**

### Other Instances:

This problem has been reported to Microsoft in the following bug tickets:

* [#668724 - MSDataSetGenerator generates incorrect output sometimes][MS 668724]
* [#733077 - MSDataSetGenerator does not generate TypedTableBase<T> derived classes][MS 733077]

It is also addressed in the SO Question: 

* [Typed Dataset not using TypedTableBase in .NET 4][SO Question]

[MS 668724]: http://connect.microsoft.com/VisualStudio/feedback/details/668724/
[MS 733077]: http://connect.microsoft.com/VisualStudio/feedback/details/733077/
[SO Question]: https://stackoverflow.com/a/5172739/1366033

[walkthrough]: http://imgur.com/a/H9nwo

I have an XML Schema Definition (XSD) file in Visual Studio 2010. The DataSet Designer should [generate a strongly typed dataset][2] in the <code><i>&lt;name&gt;</i>.designer.vb</code> file

Depending on a number of errant factors, it seems to sporadically provide strong typing for enumerable operations (used in LINQ or for each loops)

For instance, sometimes the generated code base is able to detect the type, and sometimes it's not:

[![Screenshot Code Examples][1]][1]

The offending code seems to be whether or not the generated file has the function:



    Public Overridable Function GetEnumerator() As IEnumerator Implements IEnumerable.GetEnumerator
        Return Me.Rows.GetEnumerator
    End Function

If it does, then calling the enumerator for the function will return a boring `object`.  
If it doesn't, then the enumerator will return the appropriate type.

## My Question:

### How can I get it to consistently generate the appropriate behavior?

Our source code doesn't contain generated code, so each developer needs to generate it for themselves.  This results in some machines getting compiler errors with improper typing, while others don't... with *the same exact source code*.

Some things that appear to having something to do with it:

* Assembly version targeted to .NET 4.0 VS .NET 4.0 Client
* Whether or not the XSD, designer, or usage files are open during generation
* Others?

### Possible Workarounds:

* Include strong typing / casting with all declarations
* Include properly generated file in source control


[1]: https://i.stack.imgur.com/N91Xh.png
[2]: https://learn.microsoft.com/en-us/visualstudio/data-tools/create-and-configure-datasets-in-visual-studio