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Possible solutions for an .Net 4 compiler bug that raise an MissingMemberException by acessing the index property of an SqlParameterCollection from an SqlCommand

, 14 May 2014 CPOL
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In legacy applications you can get a MissingMemberException bei acessing a SqlParameterCollection if you work with object-variables there are reference a SqlCommand-Instance.

Introduction

After i megrate a legacy application from ASP.Net 3.5 to ASP.Net 4 I was very surprised that I get a MissingFieldException when the code attempted to access an out parameter and return value ​​of a storage procedure by using the index property of an SqlParameterCollection.

After I investigated the cause of the problem, i stated, it must be a compiler error.

The cause of the problem was that the code with an object-variable worked, which was assigned an instance of a sqlcommand-objects. the compiler now correctly recognized that 'Parameters' is a SqlParameterCollection. However, they now try to access it and retrieve parameters on the basis of the indexes in the collection or the names, you get refillable following exception. However, the same code works fine under ASP.Net 2.0 and 3.5.

The Exception

System.MissingMemberException: Overload resolution failed because no accessible 'Parameters' 
accepts this number of arguments.  

Example

Dim cmd = new SqlCommand(...)
cmd.Parameters.Add("@erg").Value = 1
Dim val as Int32 = cmd.Parameters("@erg").Value '<--MissingMemberException 

Solution 1

One can circumvent this behavior by using the correct typ for the variable instead of an object variable:

Dim cmd AS new SqlCommand(...) '<--use the correct typ
cmd.Parameters.Add("@erg").Value = 1
Dim val as Int32 = cmd.Parameters("@erg").Value '<--Works fine

Solution 2

Or you can cast the Parameters-Propertie to an SqlParameterCollection and it will also work.

Dim cmd = new SqlCommand(...)
cmd.Parameters.Add("@erg").Value = 1
Dim val as Int32 = DirectCast(cmd.Parameters, SqlParameterCollection)("@erg").Value '<--Works fine too 

Note

Parameters.GetType will return SqlParameterCollection but do not be fooled.

Dim cmd = new SqlCommand(...)
cmd.Parameters.GetType() '<-- Return SqlParameterCollection

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

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About the Author

Peter BCKR
Software Developer (Senior)
Germany Germany
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