无法在LINQ to EF查询中创建常量值

Question

I am trying to retrieve data from a user class webpages_membership for verifying a token password change.

Wehn I try to run this query to get the necessary information from the database:

bool any = ttf.webpages_Membership
    .Any(x => x.UserId.Equals(userid)
         && x.PasswordVerificationToken == rt
         && x.PasswordVerificationTokenExpirationDate < DateTime.Now);

if (any == true) {

}

I get this exception

Unable to create a constant value of type 'DBContext.Models.Customers'. Only primitive types or enumeration types are supported in this context.

How can I avoid that exception?

Answer 1

Use this, to ensure that the LINQ expression only have constant values. Do also use == instead of .Equals (I'm not sure if .Equals can be correctly processed by LINQ. Perhaps it's possible, but I'm sure that == works fine).

var now = DateTime.Now;

ttf.webpages_Membership
    .Any(x => x.UserId == userid && 
         x.PasswordVerificationToken == rt &&
         x.PasswordVerificationTokenExpirationDate < now);

LINQ examines the expression tree of the lambda predicate, and can transfer constant values to the server. I think it doesn't treat DateTime.Now as a constant, unless you capture it in a variable as shown.