Android, MongoDB, MongoLab Hosted Sample App Part Two

This tutorial describes how to perform READ and UPDATE operations on a Mongolab hosted Mongodb database using a REST API. The first part of the tutorial can also be found at this blog

Lets dive in….

I have updated the structure of my contact record to the following.

/**
* Formats the contact details for MongoHLab Posting
* @param contact: Details of the person
* @return
*/
public String createContact(MyContact contact)
{
return String
.format("{\"first_name\": \"%s\", "
+ "\"last_name\": \"%s\", \"email\": \"%s\", "
+ "\"phone\": \"%s\"}",
contact.first_name, contact.last_name, contact.email, contact.phone);
}

MongoDB allows you to have a dynamic schema. Feel free to experinment with various schemas when you are done with this tutorial.

This code can be downloaded from github at this link

Figure 1: List of contacts    Figure 2: Select and update a given record

 

Async Task to fetch contacts

package com.wordpress.michaelkyazze.codeperspective102.MongoLab;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.ArrayList;

import android.os.AsyncTask;

import com.mongodb.BasicDBList;
import com.mongodb.BasicDBObject;
import com.mongodb.DBObject;
import com.wordpress.michaelkyazze.codeperspective102.MyContact;
/**
* Async Task to retrieve your stored contacts from mongolab
* @author KYAZZE MICHAEL
*
*/
public class GetContactsAsyncTask extends AsyncTask<MyContact, Void, ArrayList<MyContact>> {
static BasicDBObject user = null;
static String OriginalObject = "";
static String server_output = null;
static String temp_output = null;

@Override
protected ArrayList<MyContact> doInBackground(MyContact... arg0) {

ArrayList<MyContact> mycontacts = new ArrayList<MyContact>();
try
{

QueryBuilder qb = new QueryBuilder();
URL url = new URL(qb.buildContactsGetURL());
HttpURLConnection conn = (HttpURLConnection) url
.openConnection();
conn.setRequestMethod("GET");
conn.setRequestProperty("Accept", "application/json");

if (conn.getResponseCode() != 200) {
throw new RuntimeException("Failed : HTTP error code : "
+ conn.getResponseCode());
}

BufferedReader br = new BufferedReader(new InputStreamReader(
(conn.getInputStream())));

while ((temp_output = br.readLine()) != null) {
server_output = temp_output;
}

// create a basic db list
String mongoarray = "{ artificial_basicdb_list: "+server_output+"}";
Object o = com.mongodb.util.JSON.parse(mongoarray);

DBObject dbObj = (DBObject) o;
BasicDBList contacts = (BasicDBList) dbObj.get("artificial_basicdb_list");

for (Object obj : contacts) {
DBObject userObj = (DBObject) obj;

MyContact temp = new MyContact();
temp.setDoc_id(userObj.get("_id").toString());
temp.setFirst_name(userObj.get("first_name").toString());
temp.setLast_name(userObj.get("last_name").toString());
temp.setEmail(userObj.get("email").toString());
temp.setPhone(userObj.get("phone").toString());
mycontacts.add(temp);

}

}catch (Exception e) {
e.getMessage();
}

return mycontacts;
}
}

View contacts Activity

package com.wordpress.michaelkyazze.codeperspective102;

import java.util.ArrayList;
import java.util.concurrent.ExecutionException;

import android.app.ListActivity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;
import com.wordpress.michaelkyazze.codeperspective101.R;
import com.wordpress.michaelkyazze.codeperspective102.MongoLab.GetContactsAsyncTask;

/**
* This activity retrieves the mongolab contacts and displays them in a listview.
* @author KYAZZE MICHAEL
*
*/
public class ViewContactsActivity extends ListActivity{
ArrayList<MyContact> returnValues = new ArrayList<MyContact>();
ArrayList<String> listItems = new ArrayList<String>();
String valueTOUpdate_id;
String valueTOUpdate_fname;
String valueTOUpdate_lname;
String valueTOUpdate_phone;
String valueTOUpdate_email;

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

//Get your cloud contacts
GetContactsAsyncTask task = new GetContactsAsyncTask();
try {
returnValues = task.execute().get();
} catch (InterruptedException e) {
e.printStackTrace();
} catch (ExecutionException e) {
e.printStackTrace();
}

for(MyContact x: returnValues){

listItems.add(x.getFirst_name());
}

setListAdapter(new ArrayAdapter<String>(this,
android.R.layout.simple_list_item_1, listItems));
}
@Override
protected void onListItemClick(ListView l, View v, int position, long id) {
super.onListItemClick(l, v, position, id);

String selectedValue = (String) getListAdapter().getItem(position);
Toast.makeText(this, selectedValue, Toast.LENGTH_SHORT).show();
selectedContact(selectedValue);

Bundle dataBundle = new Bundle();
dataBundle.putString("_id", valueTOUpdate_id);
dataBundle.putString("first_name", valueTOUpdate_fname);
dataBundle.putString("last_name", valueTOUpdate_lname);
dataBundle.putString("phone", valueTOUpdate_phone);
dataBundle.putString("email", valueTOUpdate_email);
Intent moreDetailsIntent = new Intent(this,UpdateContactsActivity.class);
moreDetailsIntent.putExtras(dataBundle);
startActivity(moreDetailsIntent);
}

/*
* Retrieves the full details of a selected contact.
* The details are then passed onto the Update Contacts Record.
*
* This is a quick way for demo purposes.
* You should consider storing this data in a database, shared preferences or text file
*/
public void selectedContact(String selectedValue){
for(MyContact x: returnValues){
if(selectedValue.contains(x.getFirst_name())){
valueTOUpdate_id = x.getDoc_id();
valueTOUpdate_fname = x.getFirst_name();
valueTOUpdate_lname = x.getLast_name();
valueTOUpdate_phone = x.getPhone();
valueTOUpdate_email = x.getEmail();
}
}

}
}

Happy Coding 🙂