Displaying multiple colors on a single data bar

like below fixes the issue You can do this assuming that you have set the reverse relationship for pupilID (i.e. a relationship from Pupil to the Loan). If you call that relationship loan, and have an NSArrayController, PupilsController bound to the collection of Pupils, then your first table could be bound to PupilsController.arrangedObjects.loan.loadID and your other columns bound as you'd expect.
On a purely stylistic side note, the pupilID property would more appropriately be named pupil. Core Data is no an ORM and you're not in SQL JOIN land any more. Name the properties what they are, not how they're implemented under the hood by Core Data.

will be helpful for those in need Different colors for single series(or elements of same series) is not yet implemented or provided by the Achartengine library... :
But there are methods using multiple series or Stacked bar graph

   int[] expense = {50, 75, 100, 125, 150, 175, 200, 225 };

  static ArrayList<Integer> series1 = new ArrayList<Integer>();
  static ArrayList<Integer> series2 = new ArrayList<Integer>();
  static ArrayList<Integer> series3 = new ArrayList<Integer>();

for(int i=0;i<expense.lenght;i++)
 { 
  if(expense[i]> 50 & expense[i]<100)
   { series1.add(expense[i]);
     series2.add(0);
    series3.add(0);}

if(expense[i]> 100 & expense[i]<150)
 {.......}
}

Hope this helps Another solution is to set array of colors for series, then set colorByPoint: true, see: http://jsfiddle.net/7VNwk/2/

        series: [{
            type: 'column',
            name: 'Vengadesh',
            data: [2, 2, 2],
            colors: ['blue', 'red', 'green'],
            colorByPoint: true

        }]

With these it helps You should do one request for multiple users, then iterate over them:
Get all users:

// rather than getting just user 1
url: USERS_URL,

const users$ = sources.HTTP // users (plural)
.filter(res$ => res$.request.url.indexOf(USERS_URL) === 0)
.mergeAll()
.map(res => res.body)
.startWith([]); // start with an empty array

users.map(user => 
  div('.user-details', [
    h1('.user-name', user.name),
    h4('.user-email', user.email),
    a('.user-website', {href: user.website}, user.website)
  ])
)

function main(sources) {
  const USERS_URL = 'http://jsonplaceholder.typicode.com/users/';
  const getAllUsers$ = sources.DOM.select('.get-all').events('click')
    .map(() => {
      return {
        url: USERS_URL,
        method: 'GET'
      };
    });

  const users$ = sources.HTTP
    .filter(res$ => res$.request.url.indexOf(USERS_URL) === 0)
    .mergeAll()
    .map(res => res.body)
    .startWith([])

  const vtree$ = users$.map(users => {
    return div('.users', [
      button('.get-all', 'Get all users'),
      ...users.map(user => 
        div('.user-details', [
          h1('.user-name', user.name),
          h4('.user-email', user.email),
          a('.user-website', {href: user.website}, user.website)
        ])
      )
    ])
  });

  return {
    DOM: vtree$,
    HTTP: getAllUsers$
  };
}

To fix this issue Change your compile dependency to compile 'com.github.PhilJay:MPAndroidChart:v2.2.4' I tried your code with that version of MpAndroidChart and it worked perfectly, when I changed to the version you used, same it produced the error you have.