使用LINQ在XML文件中搜索2个不同的元素

Question

I want to use the following linq search, but to modify it so it will also search in users and admins.

NAME , ID and PASS are strings given for compare. If all 3 match, then the program knows what kind of user it is, admin or user, and moves from there. Otherwise, he isn't in any list and an error will show.

XElement xelement = XElement.Load(@"c:\user.xml");
IEnumerable<XElement> users = xelement.Elements();
foreach (var user in users)
{
  if((user.Element("Id").Value==ID)&&(user.Element("Username").Value==NAME)&&(user.Element("Password").Value==PASS))

}

The xml file is built like this:

<Data>    
    <UserList>
        <User Id="123" Username="abc" Password="abc123"></User>
    </UserList>
    <AdminList>
        <Admin Id="123" Username="abc" Password="abc123"></Admin>
    </AdminList>
</Data>    

Answer 1

Your current code uses LINQ to XML classes, but you don't actually use any LINQ queries.

What you can do is:

1. Get admins and users separately

    XDocument xDoc = XDocument.Load(@"c:\\user.xml"); var admins = xDoc.Root.Element("AdminList").Elements("Admin"); var users = xDoc.Root.Element("UserList").Elements("User"); 

2. Concatenate them together:

    var adminsAndUsers = admins.Select(x => new { Element = x, Type = "Admin" }) .Concat(users.Select(x => new { Element = x, Type = "User" })); 

3. Query result collection looking for matching user. I used (string)XAttribute casting instead of XAttribute.Value property, because it's more safe to use (won't throw an exception when attribute does not exist).

    var user = adminsAndUsers.FirstOrDefault( x => (string)x.Element.Attribute("Id") == ID && (string)x.Element.Attribute("Username") == NAME && (string)x.Element.Attribute("Password") == PASS); 

4. Check query results

    if(user != null) { // user is there var type = user.Type; } else { // no user matches } 

Answer 2

try this solution

structure

 public struct test
        {
            public bool isStudent;
            public string id;
            public string Username;
            public string Password;
        }



List<test>  users = doc.Descendants("User").Where(e => e.Attribute("Id").Value == "123").Select(e => new test{ isStudent = true, id = e.Attribute("Id").Value, Username = e.Attribute("Username").Value, Password = e.Attribute("Username").Value }).ToList();
              List<test>  admins = doc.Descendants("Admin").Where(e => e.Attribute("Id").Value == "123").Select(e => new test { isStudent = false, id = e.Attribute("Id").Value, Username = e.Attribute("Username").Value, Password = e.Attribute("Username").Value }).ToList();
            List<test> allTogether = users.Concat(admins).ToList();
            foreach (var xElement in allTogether)
            {
               //check if xElement property isStudent is true
            }

now in allTogether list you can check avery property that you need.