Android app knows names of Backendless table and column. How to get data?

General
1

Without knowing what is in the table, but only knowing the name of the Backendless table and column, how can Android app fetch data from Backendless table?

2

Yes, please see the examples in the docs:
https://backendless.com/docs/android/doc.html#data_basic_search

3

Thanks.

4

I created a Backendless app called Contact, then I used codeGen to make a download zip. I opened the zip and opened file in Android Studio. However, it failed to run on my phone and on the emulator with Nexus 5.

I want to use the example code in class Contact and the asynchronous method saveNewContact() to learn how to save info to a table in Backendless.
(Contact class in https://backendless.com/docs/android/doc.html#data_basic_search)

5

Can you provide more details on the failure to run?

6

I managed to save data into Backendless table, now I am trying to retrieve that data. I don’t understand how.

The following code has compile errors, but shows what I am trying to do.

package com.examples.contact;

import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.widget.Toast;
import com.backendless.Backendless;
import com.backendless.BackendlessUser;
import com.backendless.IDataStore;
import com.backendless.async.callback.AsyncCallback;
import com.backendless.exceptions.BackendlessFault;
import com.backendless.persistence.DataQueryBuilder;
import java.util.List;
import java.util.Map;

public class FindContactActivity extends Activity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.find_contact);

    Backendless.setUrl( Defaults.SERVER_URL );
    Backendless.initApp( getApplicationContext(), Defaults.APPLICATION_ID, Defaults.API_KEY );
}
void onFindContact() {

    IDataStore<Map> contactStorage = Backendless.Data.of( "Contact" );
    DataQueryBuilder queryBuilder = DataQueryBuilder.create();

    // set where clause
    queryBuilder.setWhereClause( "age < 30" );

    // set related columns
    queryBuilder.setRelated( "address", "phoneNumber" );

    // request sorting
    queryBuilder.setSortBy( "name" );

    //set offset and page size
    queryBuilder.setPageSize( 20 );
    queryBuilder.setOffset( 40 );

    contactStorage.find( queryBuilder, new AsyncCallback&lt;List&lt;Map&gt;>()
    {
        @Override
        public void handleResponse( List&lt;Map&gt; contactObjects )
        {
            Log.i( "MYAPP", "Retrieved " + contactObjects.size() + " objects" );
            Toast.makeText(FindContactActivity.this,"Retrieved " + contactObjects.size() + " objects from Backendless table", Toast.LENGTH_LONG).show();

            BackendlessUser user = Backendless.UserService.CurrentUser();
            if( user != null )
            {
                // get user's phone number (i.e. custom property)
                String phoneNumber = (String) user.getProperty( "phoneNumber" );
                Toast.makeText( FindContactActivity.this, String.format( "phone number: %s", phoneNumber ), Toast.LENGTH_LONG ).show();

                // get user's age (i.e. custom property)
                String age = (String) user.getProperty( "age" );
                Toast.makeText( FindContactActivity.this, String.format( "age: %s", age ), Toast.LENGTH_LONG ).show();

                // get user's adress (i.e. custom property)
                String adress = (String) user.getProperty( "adress" );
                Toast.makeText( FindContactActivity.this, String.format( "adress: %s", adress ), Toast.LENGTH_LONG ).show();
            }

        @Override
        public void handleFault( BackendlessFault fault )
        {
            //Log.e( "MYAPP", "Server reported an error " + fault.getMessage );//compile error at 'getMessage'
            Toast.makeText(FindContactActivity.this,"Backendless Server reported an error ", Toast.LENGTH_LONG).show();
        }
    });
    //&lt;/Map&gt;  //compile error at '&lt;/map&gt;'

}

}

7

If you could provide details on the actual compiler errors, it would help us help you locate the problem…