How to Load Related Data Objects – The ‘Auto-Load’ Approach

private static void printLocations(List<Location> locations) {
   if (locations == null) {
       Log.i(TAG, "Restaurant locations have not been loaded");
   } else if (locations.size() == 0) {
       Log.i(TAG, "There are no related locations");
   } else {
       for (Location location : locations) {
           Log.i(TAG, "Location: Street address - " + location.getStreetAddress() + ", City - " + location.getCity());
       }
   }
}

API example:

private static void fetchingFirstPageAsync() {
   final long startTime = System.currentTimeMillis();

   final AsyncCallback<List<Restaurant>> callback = new AsyncCallback<List<Restaurant>>() {
       @Override
       public void handleResponse(List<Restaurant> restaurants) {
           Log.i(TAG, "Loaded " + restaurants.size() + " restaurant objects");

           for (Restaurant restaurant : restaurants) {
               Log.i(TAG, "Restaurant name = " + restaurant.getName());
               printLocations(restaurant.getLocations());
           }

           Log.i(TAG, "Total time (ms) - " + (System.currentTimeMillis() - startTime));
       }

       @Override
       public void handleFault(BackendlessFault fault) {
           Log.e(TAG, fault.getMessage());
       }
   };

   Backendless.Data.of(Restaurant.class).getObjectCount(new AsyncCallback<Integer>() {
       @Override
       public void handleResponse(Integer count) {
           Log.i(TAG, "Total restaurants in the Backendless storage - " + count);
           Backendless.Data.of(Restaurant.class).find(callback);
       }

       @Override
       public void handleFault(BackendlessFault fault) {
           Log.e(TAG, fault.getMessage());
       }
   });
}

private fun printLocations(locations: List<Location>?) {
   when {
       locations == null -> Log.i(TAG, "Restaurant locations have not been loaded")
       locations.size == 0 -> Log.i(TAG, "There are no related locations")
       else -> for (location in locations) {
           Log.i(TAG, "Location: Street address - ${location.streetAddress}, City - ${location.city}")
       }
   }
}

API example:

private fun fetchingFirstPageAsync() {
   val startTime = System.currentTimeMillis()

   val callback = object : AsyncCallback<List<Restaurant>> {
       override fun handleResponse(restaurants: List<Restaurant>) {
           Log.i(TAG, "Loaded ${restaurants.size} restaurant objects")

           for (restaurant in restaurants) {
               Log.i(TAG, "Restaurant name = ${restaurant.name}")
               printLocations(restaurant.locations)
           }

           Log.i(TAG, "Total time (ms) - ${System.currentTimeMillis() - startTime}")
       }

       override fun handleFault(fault: BackendlessFault) {
           Log.e(TAG, fault.message)
       }
   }

   Backendless.Data.of(Restaurant::class.java).getObjectCount(object : AsyncCallback {
       override fun handleResponse(count: Int?) {
           Log.i(TAG, "Total restaurants in the Backendless storage - $count")
           Backendless.Data.of(Restaurant::class.java).find(callback)
       }

       override fun handleFault(fault: BackendlessFault) {
           Log.e(TAG, fault.message)
       }
   })
}

@interface Restaurant : NSObject

@property (strong, nonatomic) NSString *name;
@property (strong, nonatomic) NSArray *locations;

@end

@interface Location : NSObject

@property (strong, nonatomic) NSString *city;
@property (strong, nonatomic) NSString *street;

@end

Method to print out related locations:

- (void)printLocations:(NSArray<Location *> *)locations {
    if (!locations) {
        NSLog(@"Restaurant locations have not been loaded");
    }
    else {
        if (locations.count == 0) {
            NSLog(@"There are no related locations");
        }
        else {
            for (Location *location in locations) {
                NSLog(@"Location: Street address - %@, City - %@", location.street, location.city);
            }
        }
    }
}

API example:

NSLog(@"============ Fetching first page ============");
    
NSDate *startTime = [NSDate date];
DataStoreFactory *dataStore = [Backendless.shared.data of:[Restaurant class]];
    
[dataStore findWithResponseHandler:^(NSArray *restaurants) {
    NSLog(@"Loaded %lu restaurant objects", (unsigned long)restaurants.count);
        
    [dataStore getObjectCountWithResponseHandler:^(NSInteger totalRestaurants) {
        NSLog(@"Total restaurants in the Backendless storage - %li",(long)totalRestaurants);
        for (Restaurant *restaurant in restaurants) {
            NSLog(@"\nRestaurant name = %@", restaurant.name);
            [self printLocations:restaurant.locations];
        }
        NSLog(@"Total time (ms) - %g", 1000*[[NSDate date] timeIntervalSinceDate:startTime]);
    } errorHandler:^(Fault *fault) {
        NSLog(@"Error: %@", fault.message);
    }];
        
} errorHandler:^(Fault *fault) {
    NSLog(@"Error: %@", fault.message);
}];

@objcMembers class Restaurant: NSObject {
    var name: String?
    var locations: [Location]?
}

@objcMembers class Location: NSObject {
    var city: String?
    var street: String?
}

Method to print out related locations:

func printLocations(_ locations: [Location]?) {
    if locations == nil {
        print("Restaurant locations have not been loaded")
    }
    else if let locations = locations {
        if locations.count == 0 {
            print("There are no related locations")
        }
        else {
            for location in locations {
                if let city = location.city,
                    let street = location.street {
                    print("Location: Street address - \(street), City - \(city)")
                }
            }
        }
    }
}

API example:

print("============ Fetching first page ============")
        
let startTime = Date()
let dataStore = Backendless.shared.data.of(Restaurant.self)
        
dataStore.find(responseHandler: { restaurants in            
    print("Loaded \(restaurants.count) restaurant objects")

    dataStore.getObjectCount(responseHandler: { totalRestaurants in
        print("Total restaurants in the Backendless storage - \(totalRestaurants)")
                
        if let restaurants = restaurants as? [Restaurant] {
            for restaurant in restaurants {
                print("\nRestaurant name = \(restaurant.name ?? "")")
                self.printLocations(restaurant.locations)
            }
            print("Total time (ms) - \(Int(Date().timeIntervalSince(startTime) * 1000))")
        }
                
    }, errorHandler: { fault in
        print("Error: \(fault.message ?? "")")
    })
}, errorHandler: { fault in
    print("Error: \(fault.message ?? "")")
})

const Backendless = require('backendless')
/*
 Or use `import Backendless from 'backendless'` for client side.
 If you don't use npm or yarn to install modules, you can add the following line
 <script src="//api.backendless.com/sdk/js/latest/backendless.min.js"></script>
 to your index.html file and use the global Backendless variable.
*/

Backendless.initApp('YOUR_APP_ID', 'YOUR_JS_API_KEY')

const loadRestaurants = () => {
  return Backendless.Data.of('Restaurant').find()
}

const onSuccess = restaurants => {
  restaurants.forEach(restaurant => {
    printLocations(restaurant.locations)
  })
}

const printLocations = locations => {
  if (!locations) {
    return console.log('Restaurant locations have not been loaded')
  }

  if (!locations.length) {
    return console.log('There are no related locations')
  }

  locations.forEach(location => {
    console.log(`Location: Street address - ${ location.streetAddress }, City - ${ location.city }`)
  })
}

const onError = error => {
  console.error('Server reported an error: ', error.message)
  console.error('error code: ', error.code)
  console.error('http status: ', error.status)
}

Promise.resolve()
  .then(loadRestaurants)
  .then(onSuccess)
  .catch(onError)

static void _printLocations(List<Map> locations) {
  if (locations == null) {
    print("Restaurant locations have not been loaded");
  } else if (locations.isEmpty) {
    print("There are no related locations");
  } else {
    for (Map location in locations) {
      print("Location: Street address - ${location['streetAddress']}, City - ${location['city']}");
    }
  }
}

API example:

static void _fetchingFirstPageAsync() {
   int startTime = DateTime.now().millisecondsSinceEpoch;

   Backendless.Data.of("Restaurant").getObjectCount().then((count) {
     print("Total restaurants in the Backendless storage - $count");
    
     Backendless.Data.of("Restaurant").find().then((restaurants) {
       print("Loaded ${restaurants.length} restaurant objects");

       restaurants.forEach((restaurant) {
         print("Restaurant name = ${restaurant['name']}");
         _printLocations(restaurant['locations'].cast

============ Fetching first page using the SYNC API ============
Loaded 4 restaurant objects
Total restaurants in the Backendless storage - 4
Restaurant name = McDonald's
There are no related locations
Restaurant name = Buca Di Bepo
There are no related locations
Restaurant name = Cantina Laredo
Location: Street address - 123 Main St., City - Frisco
Restaurant name = Endless Sweets
There are no related locations
Total time (ms) - 548
============ Fetching first page using the ASYNC API ============
Loaded 4 restaurant objects
Total restaurants in the Backendless storage - 4
Restaurant name = McDonald's
There are no related locations
Restaurant name = Buca Di Bepo
There are no related locations
Restaurant name = Cantina Laredo
Location: Street address - 123 Main St., City - Frisco
Restaurant name = Endless Sweets
There are no related locations
Total time (ms) - 305