如何在 C# 中使用 flag 属性从枚举中取回位掩码值？

Question

In our database we have a bitmask that represents what types of actions a user can make.

In our C# client when we retrieve this integer value from the database we construct an enum/flag. It looks somewhat like the following:

[Flags]
public enum SellPermissions
{
    Undefined = 0,
    Buy = 1,
    Sell = 2,
    SellOpen = 4,
    SellClose = 8
    // ...
}

In our application I have an edit permissions page which I then use to modify the value of this enum using the bitwise OR on different enum values.

permissions = SellPermisions.Buy | SellPermissions.Sell;

Now, after these changes are made, in my database call I need to call an update/insert sproc which is expecting an integer value.

How do I get the integer bitwise value back out of my enum/flag so I can set the modified permissions in the database?

Answer 1

我能够通过将变量转换为int来实现。

int newPermissions = (int)permissions.

Answer 2

int permissionsValue = (int) permissions;

Answer 3

You can use HasFlag() like this:

SellPermissions permissions = SellPermissions.Buy | SellPermissions.Sell;

if(permissions.HasFlag(SellPermissions.Sell))
{
    MessageBox.Show("You have Sell permissions");
}