LINQ動態查詢

Question

如何動態地生成LINQ查詢：

int[] IDArray = {55, 36}; 

public IQueryable<ContactListView> FindAllContacts(int loggedUserID, int[] IDArray) 
{ 
    var result = (
       from contact in db.Contacts 

       //Start of dynamic part... 
       where 
       contact.UserID == loggedUserID 
       foreach (var id in IDArray) 
       { 
        where contact.UserID == id 
       } 
       // End of dynamic part 

       orderby contact.ContactID descending       
       select new ContactListView 
       { 
        ContactID = contact.ContactID, 
        FirstName = contact.FirstName, 
        LastName = contact.LastName        
       }); 

    return result; 
} 

感謝，
島

Answer 1

你就不能使用Contains？我假設你想要生成一個具有IN子句的查詢。這裏有一個例子：Creating in queries with linq to sql。

int[] IDArray = {55, 36}; 

public IQueryable<ContactListView> FindAllContacts(int loggedUserID, int[] IDArray) 
{ 
    var result = (
       from contact in db.Contacts 
       where contact.UserID == loggedUserID 
        && IDArray.Contains(contact.UserID) 
       orderby contact.ContactID descending       
       select new ContactListView 
       { 
        ContactID = contact.ContactID, 
        FirstName = contact.FirstName, 
        LastName = contact.LastName        
       }); 

    return result; 
} 

Answer 2

你可能想where IDArray.Contains(contact.UserID)