Spatial Data Delete API

There are two way to delete a spatial value from an object in the database:

1. Using Backendless Console
2. Using API

Deleting Data with Console

To delete a spatial value in console, simply clear out the contents of a cell and press Enter. Backendless Console confirms that the object has been updated:

Deleting Data with the API

Deleting a spatial value from an object using the API is technically the object update operation with the spatial value property set to null. The following algorithm can be used to perform deletion:

1. Retrieve from the database the data object which contains the spatial property to be deleted.
2. Set the property value to null.
3. Save the object back in the database.

The example below demonstrates the approach:

Custom Class ApproachDictionary/Map Approach

Objective-CSwift

Person class:

@interface Person : NSObject

@property (strong, nonatomic) BLPoint *location;

@end

Code to delete a spatial property value in the database:

[[Backendless.shared.data of:[Person class]] findFirstWithResponseHandler:^(Person *firstPerson) {
    firstPerson.location = nil;
    [[Backendless.shared.data of:[Person class]] saveWithEntity:firstPerson responseHandler:^(NSDictionary *response) {
        // location has been deleted
    } errorHandler:^(Fault *fault) {
        NSLog(@"Error: %@", fault.message);
    }];
} errorHandler:^(Fault *fault) {
    NSLog(@"Error: %@", fault.message);
}];

Building class:

@objcMembers class Building: NSObject {
    var objectId: String?
    var name: String?
    var shape: BLPolygon?
}

Code to save an object in the database:

[[Backendless.shared.data of:[Person class]] findFirstWithResponseHandler:^(Person *firstPerson) {
    firstPerson.location = nil;
    [[Backendless.shared.data of:[Person class]] saveWithEntity:firstPerson responseHandler:^(NSDictionary *response) {
        // location has been deleted
    } errorHandler:^(Fault *fault) {
        NSLog(@"Error: %@", fault.message);
    }];
} errorHandler:^(Fault *fault) {
    NSLog(@"Error: %@", fault.message);
}];

Objective-CSwift

[[Backendless.shared.data ofTable:@"Person"] findFirstWithResponseHandler:^(NSDictionary *firstPerson) {
    NSMutableDictionary *person = [firstPerson mutableCopy];
    person[@"location"] = [NSNull null];
    [[Backendless.shared.data ofTable:@"Person"] saveWithEntity:person responseHandler:^(NSDictionary *response) {
        // location has been deleted
    } errorHandler:^(Fault *fault) {
        NSLog(@"Error: %@", fault.message);
    }];
} errorHandler:^(Fault *fault) {
    NSLog(@"Error: %@", fault.message);
}];

Backendless.shared.data.ofTable("Person").findFirst(responseHandler: { firstPerson in
    var firstPerson = firstPerson
    firstPerson["location"] = NSNull()
    Backendless.shared.data.ofTable("Person").save(entity: firstPerson, responseHandler: { response in
        // location has been deleted
    }, errorHandler: { fault in
        print("Error: \(fault.message ?? "")")
    })
}, errorHandler: { fault in
    print("Error: \(fault.message ?? "")")
})

Alternatively, the same result can be achieved using the bulk update API operation. With this approach you can delete a spatial property either in a single or multiple objects. This is done with a query (the where clause) used in the API request. For example, the following query uniquely identifies a single object: objectId = 'XXX-XXX-XXX'. Consider an example demonstrating the approach:

Objective-CSwift

NSString *whereClause = @"email = 'bob@thebuilder.com'";
NSDictionary *changes = @{@"location": [NSNull null]};
[[Backendless.shared.data ofTable:@"Person"] updateBulkWithWhereClause:whereClause changes:changes responseHandler:^(NSInteger objectsUpdated) {
    // objectsUpdated is how many objects were updated by the API call
} errorHandler:^(Fault *fault) {
    NSLog(@"Error: %@", fault.message);
}];

let whereClause = "email = 'bob@thebuilder.com'"
let changes = ["location": NSNull()]
Backendless.shared.data.ofTable("Person").updateBulk(whereClause: whereClause, changes: changes, responseHandler: { objectsUpdated in
    // objectsUpdated is how many objects were updated by the API call
}, errorHandler: { fault in
    print("Error: \(fault.message ?? "")")
})