Deleting Single Object¶

Blocking Method¶

Using Dictionary

Long result = Backendless.Data.Of( "TABLE-NAME" ).Remove( String objectId );
Long result = Backendless.Data.Of( "TABLE-NAME" ).Remove( Dictionary<string, object> entity );

Custom Class

public long Backendless.Data.Of<E>().Remove( String objectId );
public long Backendless.Data.Of<E>().Remove( E entity );

Non-Blocking API¶

Using Dictionary

void Backendless.Data.Of( "TABLE-NAME" ).Remove( String objectId, 
                                               AsyncCallback<long> responder )
void Backendless.Data.Of( "TABLE-NAME" ).Remove( Dictionary<string, object> entity, 
                                               AsyncCallback<long> responder )

Custom Class

public void Backendless.Data.Of<E>().Remove( String objectId, AsyncCallback<long> responder )
public void Backendless.Data.Of<E>().Remove( E entity, AsyncCallback<long> responder )

where:

Argument	Description
`TABLE-NAME`	Name of the table where the object represented by `System.Collections.Generic.Dictionary` or `objectId` will be deleted.
`E`	A .NET class of the data object to delete.
`entity`	.NET object to delete, must be of type E or `System.Collections.Generic.Dictionary` (depending on the method used). Must contain a value for the `objectId` property which identifies the object to be deleted.
`responder`	a responder object which will receive a callback when the method successfully deletes the object or if an error occurs. Applies to the non-blocking method only.

Return Value¶

The blocking method returns the timestamp when the object is deleted. The non-blocking call receives the return value through a callback executed on the AsyncCallback object.

Example¶

Blocking API¶

public static void DeleteContact()
{
  // create new contact object first. Then we will delete it.
  Dictionary<String, Object> contact = new Dictionary<String, Object>();
  contact.Add( "name", "Jack Daniels" );
  contact.Add( "age", 147 );
  contact.Add( "phone", "777-777-777" );
  contact.Add( "title", "Favorites" );

  Dictionary<String, Object> savedContact = Backendless.Persistence.Of( "Contact" ).Save( contact );

  // now delete the saved object
  Backendless.Persistence.Of( "Contact" ).Remove( savedContact );
}

Non-blocking API¶

public static void DeleteContactAsync()
{
  // create new contact object first. Then we will delete it.
  Dictionary<String, Object> contact = new Dictionary<String, Object>();
  contact.Add( "name", "Jack Daniels" );
  contact.Add( "age", 147 );
  contact.Add( "phone", "777-777-777" );
  contact.Add( "title", "Favorites" );

  AsyncCallback<long> deleteObjectCallback = new AsyncCallback<long>(
    deletionTime =>
    {
      System.Console.WriteLine( "object has been deleted" );
    },
    error =>
    {
    }
  );

  AsyncCallback<Dictionary<String, Object>> saveObjectCallback = new AsyncCallback<Dictionary<String, Object>>(
    savedContact =>
    {
      System.Console.WriteLine( "object has been created" );
      // now delete the saved object
      Backendless.Persistence.Of( "Contact" ).Remove( savedContact, deleteObjectCallback );
    },
    error =>
    {
    }
  );

  Backendless.Persistence.Of( "Contact" ).Save( contact, saveObjectCallback );
}

Consider the following class:

package com.sample;

public class Contact
{
  private String objectId;
  private String name;
  private int age;
  private String phone;
  private String title;

  public String getObjectId() {
    return objectId;
  }

  public void setObjectId( String objectId ) {
    this.objectId = objectId;
  }

  public String getName() {
    return name;
  }

  public void setName( String name ) {
    this.name = name;
  }

  public int getAge() {
    return age;
  }

  public void setAge( int age ) {
    this.age = age;
  }

  public String getPhone() {
    return phone;
  }

  public void setPhone( String phone ) {
    this.phone = phone;
  }

  public String getTitle() {
    return title;
  }

  public void setTitle( String title ) {
    this.title = title;
  }
}

The following code saves a new instance of the Contact class and subsequently updates it:

Blocking API¶

public void deleteContact()
{
    // make sure to put the initApp call somewhere early on 
    // in the app - main activity is the best place

    // save a new object first, so there is something to delete.
    Contact contact = new Contact();
    contact.setName( "Jack Daniels" );
    contact.setAge( 147 );
    contact.setPhone( "777-777-777" );
    contact.setTitle( "Favorites" );
    Contact savedContact = Backendless.Persistence.save( contact );

    // now delete the saved object
    Long result = Backendless.Persistence.of( Contact.class ).remove( savedContact );
 }

Non-Blocking API¶

public void deleteContact()
{
    // put the initApp call somewhere early on in your app, perhaps main activity

    // create a new object, so there is something to delete
    Contact contact = new Contact();
    contact.setName( "Jack Daniels" );
    contact.setAge( 147 );
    contact.setPhone( "777-777-777" );
    contact.setTitle( "Favorites" );

    Backendless.Persistence.save( contact, new AsyncCallback<Contact>() 
    {
      public void handleResponse( Contact savedContact )
      {
        Backendless.Persistence.of( Contact.class ).remove( savedContact, 
                                                            new AsyncCallback<Long>() 
        {
          public void handleResponse( Long response )
          {
            // Contact has been deleted. The response is the 
            // time in milliseconds when the object was deleted
          }
          public void handleFault( BackendlessFault fault )
          {
            // an error has occurred, the error code can be 
            // retrieved with fault.getCode()
          }
        } );
      }
      @Override
      public void handleFault( BackendlessFault fault )
      {
        // an error has occurred, the error code can be retrieved with fault.getCode()
      }
    });
 }