Extend Validations for Framework

Steps to Prevent Error Situations in BL Contracts

• Don’t use asynchronous calls in synchronous contracts.
• Asynchronous contracts must return a promise. When you call an asynchronous method inside an asynchronous contract, it also returns a promise. In many cases you can return the promise of the asynchronous method as a result of the contract call. The resolve or reject function chain can be manipulated inside the contract to return contract-specific information.
• If you must return a separate promise by your asynchronous contract, ensure that you cover all the outcomes of any asynchronous method that you call inside the contract.

Examples of Continuous and Broken Promise Chain

• Continuous Promise Chain: Following are the code samples for continuous promise chain in different scenarios. Returns the promise unchanged

  return someObject.doSomethingAsynchronous();

  The result is reset before the promise is resolved for extended result. Rejected promise is returned unchanged.

   return someObject.doSomethingAsynchronous().then(function(result){
   // next line converts the result into a JSON object
   return {theResult: result};
   });

  Changes the result before the promise is resolved. Rejected promise is changed to a resolved promise.

  return someObject.doSomethingAsynchronous().then(function(result){
  return {theResult: result};
  },function(error){
  return {theError: error};
  });

• Broken Promise Chain: Following is the code sample for broken promise chain in the given scenario.

  If a new deferred is introduced, all other exceptions must be handled in the contract itself.

  var deferred = when.defer();
  someObject.doSomethingAsynchronous().then(function(result){
   // all exceptions here can NOT be handled by the framework
   deferred.resolve(result);
  }, function(error){
   deferred.reject(error);
  }).catch(fuction(error) {
   deferred.reject(error);
  });
  return deferred.promise;