dapper nuget 1.7 enums mapping

c# dapper enums mysql

Question

I've encountered an issue after I upgraded to the latest version of Dapper from Nuget (v 1.7).

It always return the first enums member (that is, it fail to maps).

I am using MySQL as the database.

CREATE TABLE `users_roles` (
    `userId` INT(11) NOT NULL,
    `roleId` INT(11) NOT NULL,  
    KEY `user_id` (`userId`),
    KEY `role_id` (`roleId`)
);

INSERT INTO `users_roles` (`userId`, `roleId`) VALUES (1, 1);
INSERT INTO `users_roles` (`userId`, `roleId`) VALUES (2, 2);

public enum Role { 
  Anonymous = 0, Authenticate = 1, Administrator = 2
}

var role = Current.Db.Query<Role>(@"SELECT roleId as Role FROM users_roles
    WHERE userId=@id", new { id = 2 }).FirstOrDefault();

It gives the expected output in Dapper nuget v1.6. Is this the correct behavior for the new version (1.7)?

Update:

After doing some testing with a few console application and fresh mvc3 appications I found that the behavior of Dapper enum mapping is inconsistent when you map the enum type directly.

However, mapping an enum as a property of a class somehow consistently returns the correct map

public class User
{
   public int Id { get; set; }
   public Role Role { get; set; }
}

var user = Current.Db.Query<User>(@"SELECT roleId as Role, userId as Id 
    FROM users_roles
    WHERE userId=@id", new { id = 2 }).FirstOrDefault();

the result of user.Role somehow returns the expected output

Popular Answer

Until the bug is fixed my workaround is to modify GetDeserializer method with extra condition

|| type.IsEnum

to use struct deserializer for enums as follows:

        private static Func<IDataReader, object> GetDeserializer(Type type, IDataReader reader, int startBound, int length, bool returnNullIfFirstMissing)
        {
...
            if (!(typeMap.ContainsKey(type) || type.IsEnum /* workaround! */ || type.FullName == LinqBinary))
            {
                return GetTypeDeserializer(type, reader, startBound, length, returnNullIfFirstMissing);
            }
            return GetStructDeserializer(type, startBound);

        }



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