The easy way to loop an XPage managed bean

I got harassed by Nathan (hmmm his blog appears to be down just now) yesterday for not contributing to the XPages dicussions out there so I thought I’d better remedy that. A quick tip is to make sure your Managed Bean implements Iterable if it contains a list of “things” and the obvious behaviour would be to loop over these things. If you implement Iterable you simple loop on the object using the “new” for-loop (when in Java) instead of first returning a List or array and then looping that with a for- or while loop.

Below is an example of a Managed Bean (just a Java-element from 8.5.3) that implements Iterable and hence it implements the iterator() method. That method should return an Iterator for the data you want to expose. Here I just return an iterator to the underlying list.

package com.example;

import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;

import lotus.domino.Database;
import lotus.domino.Document;
import lotus.domino.Session;
import lotus.domino.View;

import com.ibm.domino.xsp.module.nsf.NotesContext;

public class PeopleLister implements Iterable {
  // declarations
  private List people = new LinkedList();

  public PeopleLister() {
    NotesContext ctx = NotesContext.getCurrent();
    Session session = ctx.getCurrentSession();
    try {
      Database db = session.getDatabase(null, "names.nsf");
      View view = db.getView("People");
      Document doc = view.getFirstDocument();
      while (null != doc) {
        this.people.add(doc.getItemValue("FullName")
          .elementAt(0).toString());
        Document docTemp = view.getNextDocument(doc);
        doc.recycle();
        doc = docTemp;
      }
    } catch (Throwable t) {

    }
  }

  public Iterator iterator() {
    return this.people.iterator();
  }

  public String toString() {
    StringBuilder b =
      new StringBuilder(this.people.size() * 25);
    for (String p : this) {
      if (b.length() > 0) b.append(',').append(' ');
      b.append(p);
    }
    return b.toString();
  }

  public String[] getList() {
    return (String[]) people
      .toArray(new String[people.size()]);
  }
}

With that in mind I can just use the bean as follows from SSJS code (e.g. a Label):

var people = new com.example.PeopleLister();
var result = "";
for (p in people) {
  if (result.length() > 0) result += ", ";
  result += p;
}
return result;

Happy coding!

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