ORA-01008 with all variables bound

Question

I'm using System.Data.OracleClient which does parameter-binding by name and are verifying that CommandText and Parameters are in sync:

    public string CommandText { get; set; }
    public IEnumerable<OracleParameter> Parameters { get; set; }

    private void VerifyThatAllParametersAreBound()
    {
        var variableNames = Regex.Matches(CommandText, ":\\w+")
            .Cast<Match>().Select(m => m.Value).ToArray();
        var parameteterNames = Parameters.Select(p => p.ParameterName).ToArray();

        var unboundVariables = variableNames.Except(parameteterNames).ToArray();
        if (unboundVariables.Length > 0)
        {
            throw new Exception("Variable in CommandText missing parameter: "
                + string.Join(", ", unboundVariables) + ".");
        }

        var unboundParameters = parameteterNames.Except(variableNames).ToArray();
        if (unboundParameters.Length > 0)
        {
            throw new Exception("Parameter that is not used in CommandText: "
                + string.Join(", ", unboundParameters) + ".");
        }
    }

Still one query throws ORA-01008: not all variables bound. When manually inserting the parameter-values into the offending CommandText the query runs, so the CommandText and Parameters-values should be ok. I'm using : as prefix both for variables and parameternames and it's working for the other queries.

How can I pinpoint the cause of this exception?

Answer 1

The mistake was not specifing DBNull.Value for null-values. So

new OracleParameter(":Foo", item.Foo)

had to preplaced with

item.Foo == null 
    ? new OracleParameter(":Foo", DBNull.Value) 
    : new OracleParameter(":Foo", item.Foo)

I think it was working earlier with ODT.NET without null-checks, but have not confirmed it. Apparently System.Data.OracleClient is dropping parameters with null-value.