Reflection.Emit added properties not visible

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After performing a Pivot in SQL I end up with a datasource with a few known columns and a variable amount of unknown (at design time) columns.

I used the classic DataSet - DataTable solution, but started hitting OutOfMemory exceptions while processing the data (60,000 rows and 95 columns).

I then realized I needed a lighter weight solution and so used Reflection.Emit to construct my types at runtime. This worked perfectly giving me a 10x performance increase over the DataTables, however, the processing code was quite complex, so for simplicity sake I changed the code to generate a type that inherits from a defined base type where the base type contains the known columns and I used Reflection.Emit to define a new type extending the base class and adding the extra columns at run time.

This simplified the code nicely and I can construct and fully populate these objects correctly.

The problem is that when I bind them to a DataGrid, only the base type's columns are visible. If I add a reference to the object in the debugger I can also only see the properties of the base class (Grid.DataSource(0)), however if I check the type I can see all the properties are there - Grid.DataSource(0).GetType.GetProperties().

Anyone know why the DataGrid and other data visualizers refuse to find these added properties?

Posted 2-Feb-14 20:55pm

Brendon Webber

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Abhinav S · Answer 1 · 2014-02-02T20:58:00

Solution 1

You have to give the approrpate flags to emit fields - e.g. http://msdn.microsoft.com/en-us/library/system.reflection.fieldattributes%28v=vs.110%29.aspx[^].

Posted 2-Feb-14 20:58pm

Abhinav S

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Brendon Webber 3-Feb-14 3:18am

The backing field for my property has been defined with FieldAttributes.Private and the property has been defined with the Read and Write PropertyAttributes.

The Emit solution works when I do not inherit my generated class type from a defined base type, therefore I feel that my properties are defined correctly.

It would seem that there is an issue with extending defined types.