External module Validate

const users = [
{
  uid: '_:user1',
  username: 'user1',
  addresses: [{
    uid: '_:user1address1',
    postcode: 2444
  }]
},
{
  uid: '_:user2',
  username: 'user2',
  addresses: [
    {
      uid: '_:user2address1',
      postcode: 2000
    },
    {
      uid: '_:user2address2',
      postcode: 2000
    }
  ]
}];
const params = {
 node: user1uid,
 edgename: 'addresses',
 linkednodesuids: [user1addressuid]
};
// this will return true as user1 does have address 1
const result = await xvalidatenodelinkstxn(params, dgraphclient);

const users = [
 { username: 'user1', age: 33, street: '123 state'},
 { username: 'user2', age: 35},
 { username: 'user3'}
];

// will return true username is a predicate for every user
const result = await xValidateNodePredicatesTxn({
    nodes: userUids,
    predicates: ['username']
}, dgraphClient);