The parameterized query … expects the parameter '@units', which was not supplied

Question

I\'m getting this exception:

The parameterized query \'(@Name nvarchar(8),@type nvarchar(8),@units nvarchar(4000),@rang\' expects the parameter \'@uni

Answer 1

This extension class was useful to me a couple of times so far, for those issues:

public static class DbValueExtensions
{
    // Used to convert values coming from the db
    public static T As(this object source)
    {
        return source == null || source == DBNull.Value
            ? default(T)
            : (T)source;
    }

    // Used to convert values going to the db
    public static object AsDbValue(this object source)
    {
        return source ?? DBNull.Value;
    }
}

You would normally use it in two scenarios. First, when creating parameters for your query:

var parameters = new Dictionary
{
    { "@username", username.AsDbValue() },
    { "@password", password.AsDbValue() },
    { "@birthDate", birthDate.AsDbValue() },
};

or when parsing the SqlReader values:

while (reader.Read())
{
    yield return new UserInfo(
        reader["username"].As(),
        reader["birthDate"].As(),
        reader["graduationDate"].As(),
        reader["nickname"].As()
    );
}