CurrentUtcDateTime does not exist - Entity Framework and MySql - mysql

Question

I am having a problem with canonical functions in Entity Framework 4.1 and MySql Connector/Net 6.4.3.
According to Microsoft cannonical functions are understood and translated into the local SQL dialect by all database providers from the SQL generated by LINQ; http://msdn.microsoft.com/en-us/library/bb738626.aspx However, my code chokes on CurrentUtcDateTime(), which is listed here; http://msdn.microsoft.com/en-us/library/bb738563.aspx
Here is the LINQ query (from NopCommerce) that generates the offensive SQL:
public List<Poll> GetPolls(int languageId, int pollCount, bool loadShownOnHomePageOnly)
{
bool showHidden = NopContext.Current.IsAdmin;
var query = (IQueryable<Poll>)_context.Polls;
if (!showHidden)
{
query = query.Where(p => p.Published);
query = query.Where(p => !p.StartDate.HasValue || p.StartDate <= DateTime.UtcNow);
query = query.Where(p => !p.EndDate.HasValue || p.EndDate >= DateTime.UtcNow);
}
if (loadShownOnHomePageOnly)
{
query = query.Where(p => p.ShowOnHomePage);
}
if (languageId > 0)
{
query = query.Where(p => p.LanguageId == languageId);
}
query = query.OrderBy(p => p.DisplayOrder);
if (pollCount > 0)
{
query = query.Take(pollCount);
}
var polls = query.ToList();
return polls;
}
query.ToList() generates the SQL below:
SELECT`Project1`.`PollID`, `Project1`.`LanguageID`, `Project1`.`Name`,
`Project1`.`Published`, `Project1`.`ShowOnHomePage`, `Project1`.`DisplayOrder`,
`Project1`.`SystemKeyword`, `Project1`.`StartDate`, `Project1`.`EndDate`
FROM (SELECT`Extent1`.`PollID`, `Extent1`.`LanguageID`, `Extent1`.`Name`,
`Extent1`.`SystemKeyword`, `Extent1`.`Published`, `Extent1`.`ShowOnHomePage`,
`Extent1`.`DisplayOrder`, `Extent1`.`StartDate`, `Extent1`.`EndDate`
FROM `Nop_Poll` AS `Extent1` WHERE ((((`Extent1`.`Published` = 1) AND
((`Extent1`.`StartDate` IS NULL) OR (`Extent1`.`StartDate` <= (CurrentUtcDateTime()))))
AND ((`Extent1`.`EndDate` IS NULL) OR (`Extent1`.`EndDate` >= (CurrentUtcDateTime()))))
AND (`Extent1`.`ShowOnHomePage` = 1)) AND (`Extent1`.`LanguageID` = #p__linq__0))
AS `Project1` ORDER BY `Project1`.`DisplayOrder` ASC LIMIT 2147483647
This is error is outputed:
*FUNCTION myDatabase.CurrentUtcDateTime does not exist
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
Exception Details: MySql.Data.MySqlClient.MySqlException: FUNCTION myDatabase.CurrentUtcDateTime does not exist*
Am I missing something? Please advice. Thanks.

Answer 1

I encountered this exact same problem and lost almost two days trying to figure it out. It appears to be a bug in the EntityFramework mappings for MySql.
The solution is to move the DateTime.UtcNow calculation outside of the scoped lambda and plug in the actual value.
var utcNow = DateTime.UtcNow;
query = query.Where(p => p.Published);
query = query.Where(p => !p.StartDate.HasValue || p.StartDate <= utcNow);
query = query.Where(p => !p.EndDate.HasValue || p.EndDate >= utcNow);

Answer 2

Based on Bohemian's suggestion, I fixed this issue with a "bypass" function.
CREATE FUNCTION `your_schema`.`CurrentUtcDateTime` ()
RETURNS TIMESTAMP DETERMINISTIC
RETURN UTC_TIMESTAMP();

Answer 3

Use UTC_TIMESTAMP()