WhereFilterXform.cs

/// <summary>
/// Builds the where filter implementation.
/// </summary>
/// <param name="info">The information.</param>
/// <returns>ICommandSingleResultExpression&lt;TFilter, TResult&gt;.</returns>
public IExecutableCommandInfo BuildWhereFilterTransform(IExecutableCommandInfo info)
{
    var mappings = info.Parameters
        .Join(_processor.CommandResultInfo.RetrieveResultSetMappings(typeof(TResult)).Export(), parameter =>
                parameter.SourceColumn, pair => pair.Key,
            (parameter, pair) =>
                new Tuple<string, Type, string, string>(
                    pair.Key,                                 //Property Name
                    pair.Value.PropertyMetadata.PropertyType, //Property Type
                    parameter.ParameterName,                  //Parameter Name
                    pair.Value.ActiveAlias                    //Result Column Name
                    ))
        .GroupJoin(WhereFilterOptions, tuple => tuple.Item1, pair => pair.Key,
            (tuple, pairs) => new { tuple, comparer = pairs.Select(kvp => kvp.Value).FirstOrDefault() })
        .Select(o => new Tuple<string, Type, string, string, object>(
            o.tuple.Item1,                                          //Property Name
            o.tuple.Item2,                                          //Property Type
            o.tuple.Item3,                                          //Parameter Name
            o.tuple.Item4,                                          //Result Column Name
            o.comparer ?? GetDefaultCompareMethod(o.tuple.Item2)    //Comparer
            ));

    return new ExecutableCommandInfo
    {
        CommandText = info.CommandText + string.Concat(mappings.Select(o =>
        {
            var parameter = info.Parameters.SingleOrDefault(param => param.ParameterName == o.Item3);

            var compareFormat = string.Empty;
            //If no matching parameter or value is null or DBNull, don't add a comaparison.
            if (parameter?.Value != null && parameter.Value != DBNull.Value)
            {
                if (o.Item5 is CompareMethod)
                    compareFormat = Comparison.GetComparisonFormat((CompareMethod)o.Item5);
            }

            var value = o.Item5 as ComparisonOverride;
            compareFormat = value != null ? value.OverrideText : compareFormat;

            if (compareFormat.Contains('{'))
                compareFormat = string.Format(compareFormat, o.Item3, "[" + o.Item4 + "]");

            return compareFormat;
        })),
        DbCommandType = info.DbCommandType,
        Parameters = info.Parameters
    };
}