EntityFramework.Core.dll中出现“System.InvalidCastException”类型的异常，但未在用户代码中处理

Question

I am trying to get the long value associated to an ActivityLogType it is associated to either a create , edit , and delete record in the database.

It is used for an audit / activity log that is needed.

public enum ActivityLogType
{
    Create = 1,
    Update = 2,
    Delete = 3 
}

My getter method:

public ActivityType GetType(ActivityLogType type)
{
    var id = (long)type;

    Console.WriteLine(id); // <---- this produces a 1 in the console. So the cast works?

    return _context.ActivityTypes.Where(x => x.Id == id).FirstOrDefault(); // <-- This line throws the error 
}

UPDATE 1

un-lucky suggested using (long)ActivityLogType.Create to get the desired output. I tried this: (Still not working)

public ActivityType GetType(ActivityLogType type)
{

    switch (type)
    {
        case ActivityLogType.Create:
            return _context.ActivityTypes.Where(x => x.Id == (long)ActivityLogType.Create).FirstOrDefault();
        case ActivityLogType.Update:
            return _context.ActivityTypes.Where(x => x.Id == (long)ActivityLogType.Update).FirstOrDefault();
        case ActivityLogType.Delete:
            return _context.ActivityTypes.Where(x => x.Id == (long)ActivityLogType.Delete).FirstOrDefault();
        default:
        return null;
    }

}

UPDATE 2

Here is the ActivityType entity

public class ActivityType
{

    public ActivityType()
    {
        this.Activities = new HashSet<Activity>();
    }

    [Key, DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public long Id { get; set; }

    [Display(Name = "Label")]
    public string Label { get; set; }

    [Display(Name = "Display Order")]
    public int Order { get; set; }

    [Display(Name = "Is Active")]
    public bool IsActive { get; set; }

    [Display(Name = "Activities")]
    public virtual ICollection<Activity> Activities { get; set; }
}

Answer 1

你可以试试这个：

long id= Int64.Parse(Convert.ChangeType(type, Enum.GetUnderlyingType(type.GetType())).ToString());