Typed Dataset not using TypedTableBase in .NET 4

问题

I'm migrating our DAL class library to .NET 4 (from .NET 3.5). We're using typed datasets quite often, and we often iterate over tables:

foreach(var row in ds.MyTable) var tmp = row.ID;

This does not work anymore, as the designer changes the dataset's code so that tables do not derive from TypedTableBase<T> anymore, but from DataTable (and implement the non-generic IEnumerable). That's what the diff shows. Therefore, the row is of type object at compile-time.

Does anybody know if this is the usual behavior? At the moment, I'm doing it the way shown below, but I hope there's a more elegant solution:

foreach(var row in ds.MyTable.Cast<MyDs.MyRow>()) var tmp = row.ID;

回答1:

Just ran into this today and was able to correct it by doing the following:

Select the xsd files in the solution explorer and click "Run Custom Tool". The designer files will be regenerated using TypedTableBase instead of DataTable and IEnumerable.

回答2:

The accepted answer is mostly complete, but will not fully resolve the issue.
Here's a reproduction of my question and answer on this issue.

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:

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

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

Other Instances:

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

#668724 - MSDataSetGenerator generates incorrect output sometimes
#733077 - MSDataSetGenerator does not generate TypedTableBase derived classes

回答3:

All this is correct but in my case I had to support source code which needs to run with .Net 2.0 and .Net 4.0. My objective was to change as little code as possible.

My solution was to create a partial extension under .Net 4.0 and bind it to the 4.0 application. This looks like:

namespace NamespaceOfMyDataSet
{
    public partial class MyDataSet : global::System.Data.DataSet 
    {
        public partial class MyTypedTable : global::System.Data.TypedTableBase<MyTypedTableRow> 
        {
            public System.Data.DataRowCollection GetRows()
            {
                return this.Rows;
            }
        }
    }
}

This works like a charme!!!

来源：https://stackoverflow.com/questions/4469115/typed-dataset-not-using-typedtablebase-in-net-4

标签

.net-4.0

dataset

strongly-typed-dataset