Get a list of elements by their ID in entity framework

Question

How can I get all elements that are in another list by ID? For eg; I have List roles; I\'d like to get all roles from the database that are in this this list by their Id.

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Answer 1

var listOfRoleId = user.Roles.Select(r => r.RoleId);
var roles = db.Roles.Where(r => listOfRoleId.Contains(r.RoleId));