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i have a enum type like below
[Flags]
public enum WeekDays
{
Monday = 1,
Tuesday = 2,
Wednesday = 4,
Thursday = 8,
Friday = 16,
Saturday = 32,
Sunday = 64,
}
WeekDays dw = WeekDays.Friday | WeekDays.Monday | WeekDays.Saturday;
int dwInt = (int)dw;
var list = query.Where(f => f.FromDateTime.DayOfWeek == dwInt "??????????? what can i do there????").ToList();
898
The "|=" operator actually adds a flag to the enum, so the enum now contains two flag bits. You can use "|=" to add bits, while & will test bits without setting them. And Bitwise AND returns a value with 1 in the targeted bit if both values contain the bit.
Enum Flags Attribute The idea of Enum Flags is to take an enumeration variable and allow it hold multiple values. It should be used whenever the enum represents a collection of flags, rather than representing a single value. Such enumeration collections are usually manipulated using bitwise operators.
In Entity Framework, this feature will allow you to define a property on a domain class that is an enum type and map it to a database column of an integer type. Entity Framework will then convert the database value to and from the relevant enum as it queries and saves data.
Starting from Entity Framework 6.1, you can use the HasFlag extension method in your requests.
For example:
query.Where(f => f.FromDateTime.DayOfWeek.HasFlag(WeekDays.Friday | WeekDays.Monday)).ToList();
See https://entityframework.codeplex.com/workitem/1497 for details about the feature request and implementation.
173
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