Bug #105728 Parameter name overrides query attributes

Description:
When a query attribute and a command parameter have the exact same name, Connector/NET overwrites the value for the attribute with the value from the parameter of the same name. This prevents the value of the attribute being retrieved successfully using mysql_query_attribute_string.

It occurs whether the command is prepared or not.

How to repeat:
Use MySQL Server 8.0.26 or later, and install the query_attributes component as per https://dev.mysql.com/doc/refman/8.0/en/query-attributes.html#query-attributes-prerequisit...

Run the following C# code:

using var cmd = new MySqlCommand("select mysql_query_attribute_string('name') as attribute, @name as parameter;", connection);
cmd.Attributes.SetAttribute("name", "attribute");

cmd.Parameters.AddWithValue("name", "parameter");
// workaround: prefix the parameter name with "@"
// cmd.Parameters.AddWithValue("@name", "parameter");

// also happens when preparing the command
// cmd.Prepare();

using var reader = cmd.ExecuteReader();
while (reader.Read())
{
	// prints "parameter"; expect "attribute"
	Console.WriteLine(reader.GetValue(0));
	
	// prints "parameter"
	Console.WriteLine(reader.GetValue(1));
}

Suggested fix:
Connector/NET shouldn't send the names for parameters, but only attributes; it's not expected that adding parameters will also add attributes with the same name.

Hello Bradley Grainger,

Thank you for the bug report.
Verified as described.

Regards,
Ashwini Patil

This is no longer a bug. Please use our latest release, Connector/NET 8.0.30.

It's fixed if you don't prepare the command, but still broken if you uncomment 'cmd.Prepare();' from my example repro code.

Posted by developer:
 
Fixed as of the upcoming MySQL Connector/NET 8.0.31 release, and here's the proposed changelog entry from the documentation team:

When a query attribute and a command parameter have the exact same name,
Connector/NET overwrites the value of the attribute with the value from
the parameter, which then prevents using mysql_query_attribute_string to
retrieve an accurate value for the attribute. Connector/NET now removes
all parameter names when sending a prepared statement.

Thank you for the bug report.