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David Leedy
David Leedy

Reputation: 3593

Is is possible to do @Unique() inside Java in XPages?

When I want a unique key for documents I'm partial to using @Unique(). I like that it's based on username and time.

Is there a way to get that from inside a Java bean?

If not, what's the best way to get a unique number in Java that would not repeat?

Thanks

Upvotes: 5

Views: 1031

Answers (5)

xpagesbeast
xpagesbeast

Reputation: 816

Yes you can. When you get a handle to Session call evaluate. You can evaluate any formula expressions with this method. 

String ID = (String)session.evaluate("@Unique").elementAt(0);

Upvotes: 5

Peter Presnell
Peter Presnell

Reputation: 380

The following is the LotusScript code I developed a long time ago as part of my .DominoFramework to reproduce the behavior of @Unique(). You should be able to convert this to Java to get a set of values similar to what you are used to.

Function unique() As String
  Dim   Index       As Integer
  Try:  
    On Error GoTo Catch
    Randomize
    Unique = ""
    For Index% = 1 To 4
      Unique$ = Unique$ + Chr$(CInt(Rnd(Index%)*26)+65)
    Next Index%
    Unique$ = Unique$ + "-"
    For Index% = 6 To 11
      Unique$ = Unique$ + Chr$(CInt(Rnd(Index%)*26)+65)
    Next Index%
    Exit Function
Catch:
  Stop
  DominoException.throw Me,  Nothing
  Exit Function
End Function

Upvotes: 0

Oliver Busse
Oliver Busse

Reputation: 3395

What about this:

public String getUnique() {
    try {
        return (String) getCurrentSession().evaluate("@Unique").elementAt(0);
    } catch (NotesException e) {
        return "";
    }
}

// retrieve handle to a Notes-Domino object in the bean class
public static Session getCurrentSession() {
    FacesContext context = FacesContext.getCurrentInstance();
    return (Session) context.getApplication().getVariableResolver()
            .resolveVariable(context, "session");
}

It will return a familiar Unique string. Unfortunately with the signature of your server, not the current username when it runs in a browser. I the client it will work as intended.

Upvotes: 0

Serdar Basegmez
Serdar Basegmez

Reputation: 3355

Russell's answer is correct. But if you need a shorter unique key, you can also try this alternative:

public static String getUnique() {
    String CHARLIST = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXTZabcdefghiklmnopqrstuvwxyz";

    long number=System.currentTimeMillis();
    int base=CHARLIST.length();

    String result="";
     while (number > 0){
      result = CHARLIST.charAt((int)(number%base))+result;
      number = number/base;
     }
     return result;
}

This is basically converts the number of milliseconds from 1970 to 62-base number. You can even shorten this by getting time since 2012/12/31 or so.

Upvotes: 0

Russell Maher
Russell Maher

Reputation: 378

This is what I use whenever I need a unique number:

String controlNumber = UUID.randomUUID().toString();

Upvotes: 9

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