Friday, July 29, 2011

Using Drupal menu system callback mapping to retrieve JSON or XML data

In my previous post I talked about Drupal menu system callback mapping. Today I'm going to show you how Drupal menu system callback mapping can be used to retrive JSON or XML data.

The way to accomplish the task is to register a path for a menu item with an optional argument. If you pass that optional argument along with the request URL callback function will return JSON data else it will return XML data. In that way callback function will serve both data formats.

Following is a coding example of above mentioned scenario.

<?php
//hook_perm implementation
function example_perm() {
    return array(
        'access city'
    );
}

//hook_menu implementation
function example_menu() {
    $items = array();
 
    //menu item 
    $items['full_city_list'] = array(
        'title' => t('City List JSON'
        ), 'page callback' => 'full_city_list', 'page arguments' => array(
            1
        ), 'access arguments' => array(
            'access city'
        ), 'type' => MENU_CALLBACK);   

    return $items;
}

function full_city_list() {
 $jsonParam=arg(1);//optional argument
 $result = db_query("SELECT  tid,name FROM term_data  WHERE  vid=2 order by name ASC");
 
 if(strcmp($jsonParam, "json") == 0){
    $response = array();
    
    while ($city_data = db_fetch_object($result)) {
        $response[$city_data->name]['city_name'] = $city_data->name;
        $response[$city_data->name]['tid'] = $city_data->tid;
    }

    if (!empty($response)) {
        //encodes city data as json  
        $jsonstrCityList = json_encode($response);
        echo $jsonstrCityList;
    } else {
        return false;
    }
 }elseif(strcmp($jsonParam, "") == 0){
 //sending city data as xml
 $dom = new DOMDocument("1.0");
    $root_elm = $dom->createElement("markers");
    $root = $dom->appendChild($root_elm);    

    while ($city_data = db_fetch_object($result)) {

        $marker_elm = $dom->createElement("marker");
        $marker_node = $root->appendChild($marker_elm);

        $marker_node->setAttribute("name", $city_data->name);
        $marker_node->setAttribute("tid", $city_data->tid);
    }
    header("Content-type: text/xml");
    echo $dom->saveXML();
 }
}
?>



output for http://example.com/full_city_list/json
{"Agalawatta":{"city_name":"Agalawatta","tid":"156"},"Ahungalla":{"city_name":"Ahungalla","tid":"214"},"Akurana":{"city_name":"Akurana","tid":"164"},"Akuressa":{"city_name":"Akuressa","tid":"162"},"Aluthgama":{"city_name":"Aluthgama","tid":"120"},"Ambalangoda":{"city_name":"Ambalangoda","tid":"125"},"Ampara":{"city_name":"Ampara","tid":"211"},"Anuradhapura":{"city_name":"Anuradhapura","tid":"46"},"Arugambay":{"city_name":"Arugambay","tid":"114"},"Avissawella":{"city_name":"Avissawella","tid":"212"},"Badulla":{"city_name":"Badulla","tid":"108"},"Balangoda":{"city_name":"Balangoda","tid":"149"},"Balapitiya":{"city_name":"Balapitiya","tid":"486"},"Bandarawela":{"city_name":"Bandarawela","tid":"197"}}


output for http://example.com/full_city_list
<markers>
<marker name="Agalawatta" tid="156"/>
<marker name="Ahungalla" tid="214"/>
<marker name="Akurana" tid="164"/>
<marker name="Akuressa" tid="162"/>
<marker name="Aluthgama" tid="120"/>
<marker name="Ambalangoda" tid="125"/>
<marker name="Ampara" tid="211"/>
<marker name="Anuradhapura" tid="46"/>
<marker name="Arugambay" tid="114"/>
<marker name="Avissawella" tid="212"/>
<marker name="Badulla" tid="108"/>
<marker name="Balangoda" tid="149"/>
<marker name="Balapitiya" tid="486"/>
<marker name="Bandarawela" tid="197"/>
</markers>

Wednesday, July 20, 2011

Drupal menu system callback mapping

How does drupal menu system callback mapping happen?

When a user makes a request to drupal through a browser, using the request URL drupal menu system decides which callback function to invoke.

what is a callback function?

Callback function in this case is a php function which gets called when a user trying to access a path that has already been registered in a menu item.

In the given example-1 if a browser makes a request using the URL "http://example.com/hello", menu system will look for a menu item which contains that path and invokes the relevant callback function in this case, "hello()".

example-1

<?php

//hook_perm implementation  
function example_perm() {
    return array(
        'access hello'
    );
}

//hook_menu implementation  
function example_menu() {
    $items = array();
    //menu item   
    $items['hello'] = array(
    'title' =--> t('hello'
    ), 'page callback' => 'hello', 'page arguments' => array(
    0
    ), 'access arguments' => array(
    'access hello'
    ), 'type' => MENU_CALLBACK);

    return $items;
}

//callback function  
function hello() {
    echo "hello!";
}
?>  

Output for example-1
hello!

example-2

This example shows how to get city data in json or xml using a request URL.

<?php

//hook_perm implementation
function example_perm() {
    return array(
        'access hello'
    );
}

//hook_menu implementation
function example_menu() {
    $items = array();
    //menu item 
    $items['hello'] = array(
        'title' => t('hello'
        ), 'page callback' => 'hello', 'page arguments' => array(
            0
        ), 'access arguments' => array(
            'access hello'
        ), 'type' => MENU_CALLBACK);

    $items['full_city_list_json'] = array(
        'title' => t('City List JSON'
        ), 'page callback' => 'full_city_list_json', 'page arguments' => array(
            0
        ), 'access arguments' => array(
            'access hello'
        ), 'type' => MENU_CALLBACK);

    $items['full_city_list_xml'] = array(
        'title' => t('City List XML'
        ), 'page callback' => 'full_city_list_xml', 'page arguments' => array(
            0
        ), 'access arguments' => array(
            'access hello'
        ), 'type' => MENU_CALLBACK);

    return $items;
}

function hello() {
    echo "hello!";
}

function full_city_list_json() {
    $response = array();
    $result = db_query("SELECT  tid,name FROM term_data  WHERE  vid=2 order by name ASC");
    while ($city_data = db_fetch_object($result)) {
        $response[$city_data->name]['city_name'] = $city_data->name;
        $response[$city_data->name]['tid'] = $city_data->tid;
    }

    if (!empty($response)) {
        //encodes city data as json  
        $jsonstrCityList = json_encode($response);
        echo $jsonstrCityList;
    } else {
        return false;
    }
}

function full_city_list_xml() {
//sending city data as xml
    $dom = new DOMDocument("1.0");
    $root_elm = $dom->createElement("markers");
    $root = $dom->appendChild($root_elm);

    $result = db_query("SELECT  tid,name FROM term_data  WHERE  vid=2 order by name ASC");

    while ($city_data = db_fetch_object($result)) {

        $marker_elm = $dom->createElement("marker");
        $marker_node = $root->appendChild($marker_elm);

        $marker_node->setAttribute("name", $city_data->name);
        $marker_node->setAttribute("tid", $city_data->tid);
    }
    header("Content-type: text/xml");
    echo $dom->saveXML();
}

?>

Outputs for example-2

for http://example.com/full_city_list_json

{"Agalawatta":{"city_name":"Agalawatta","tid":"156"},"Ahungalla":{"city_name":"Ahungalla","tid":"214"},"Akurana":{"city_name":"Akurana","tid":"164"},"Akuressa":{"city_name":"Akuressa","tid":"162"},"Aluthgama":{"city_name":"Aluthgama","tid":"120"},"Ambalangoda":{"city_name":"Ambalangoda","tid":"125"},"Ampara":{"city_name":"Ampara","tid":"211"},"Anuradhapura":{"city_name":"Anuradhapura","tid":"46"},"Arugambay":{"city_name":"Arugambay","tid":"114"},"Avissawella":{"city_name":"Avissawella","tid":"212"},"Badulla":{"city_name":"Badulla","tid":"108"},"Balangoda":{"city_name":"Balangoda","tid":"149"},"Balapitiya":{"city_name":"Balapitiya","tid":"486"},"Bandarawela":{"city_name":"Bandarawela","tid":"197"}}

for http://example.com/full_city_list_xml

<markers>
<marker name="Agalawatta" tid="156"/>
<marker name="Ahungalla" tid="214"/>
<marker name="Akurana" tid="164"/>
<marker name="Akuressa" tid="162"/>
<marker name="Aluthgama" tid="120"/>
<marker name="Ambalangoda" tid="125"/>
<marker name="Ampara" tid="211"/>
<marker name="Anuradhapura" tid="46"/>
<marker name="Arugambay" tid="114"/>
<marker name="Avissawella" tid="212"/>
<marker name="Badulla" tid="108"/>
<marker name="Balangoda" tid="149"/>
<marker name="Balapitiya" tid="486"/>
<marker name="Bandarawela" tid="197"/>
</markers>


As in example-2 after you grabbed the city data in json or in xml you can parse them and use in any of your applications.

Wednesday, July 6, 2011

Parsing JSON (comes as a response to a web request) using java

JSON (JavaScript Object Notation) as in definition is a light weight data exchange format, a fat free alternative to XML. In today's post I will show you how to parse JSON (comes as a response to a web request) using java.

First download json-lib and add it to your classpath. You'll also have to add following libraries to your classpath

  1. commons-lang.jar
  2. commons-beanutils.jar
  3. commons-collections.jar
  4. commons-logging.jar
  5. ezmorph.jar

What you need next is a request url and it's response should be JSON data. You will see mine in the example code I've provided, if you know how to use firebug the task will be much more simpler. In your browser run that request you'll get the JSON data which I parse, it's lengthy that's why I didn't add it in here. If you get untidy JSON data, format it using jasonlint.

Now let's move on to the example code, it's not hard to understand, simply go through it. Refer comments for clarifications.

java code

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.URL;
import net.sf.json.JSONArray;
import net.sf.json.JSONObject;
import net.sf.json.JSONSerializer;

public class JsonParse { 

 public static void main(String[] args) {
  String jsonString = "";

  String city = "London";
  String country = "United+Kingdom";

  //This is the request url  
  String requestUrl = "http://www.bing.com/travel/hotel/hotelReferenceData.do?q="
    + city
    + "%2C+"
    + country
    + "+leave+07%2F08%2F2011+return+07%2F10%2F2011+adults%3A2+rooms%3A1&distanceFrom=22&HotelPriceRange=1%2C2%2C3%2C4&pageOffset=0&pageCount=240&cim=2011-07-08&com=2011-07-10&a=2&c=0&r=1&sortBy=PopularityDesc";
  try {
   URL url = new URL(requestUrl.toString());
   BufferedReader in = new BufferedReader(new InputStreamReader(
     url.openStream()));
   String inputLine;

   while ((inputLine = in.readLine()) != null) {
    //JSON data get stored as a string
    jsonString = inputLine;

   }
   in.close();
   //the way to parse JSON array
   JSONArray json = (JSONArray) JSONSerializer.toJSON(jsonString);
   //getting another JSON string to parse
   String parse1 = json.getString(0);
   
   //the way to parse JSON object
   JSONObject json2 = (JSONObject) JSONSerializer.toJSON(parse1);
   //getting a json array inside JSON object
   JSONArray array1 = json2.getJSONArray("hotels");

   for (int i = 0; i < array1.size(); i++) {
    //getting a JSON object inside JSON array
    JSONObject jhotelrec = array1.getJSONObject(i);    
    System.out.println("Hotel Name= "+jhotelrec.getString("name")+"\n"+"Geo Codes= "+jhotelrec.getJSONArray("geoPoint").getString(0)+","+jhotelrec.getJSONArray("geoPoint").getString(1));
    }

  } catch (IOException e) {
   e.printStackTrace();
  }
 }
 
 

}


Monday, July 4, 2011

xml parsing with java

In certain situations we java programmers may need to access information in XML documents using a java xml parser. This post will guide you to parse a xml document with java, using DOM parser and Xpath.

xmlfile.xml

Given XML document is quite lengthy, but do not worry because parsing a lengthy XML document is as easy as parsing a short XML document :) .

<a>
<e>
<hotels class="array">
   <e class="object">
    <addressLine1 type="string">4 Rue du Mont-Thabor</addressLine1>
    <amenities class="array">
     <e type="string">24</e>
     <e type="string">31</e>
     <e type="string">42</e>
     <e type="string">52</e>
     <e type="string">9</e>
    </amenities>
    <brandCode type="string">69</brandCode>
    <cachedPrice type="number">935</cachedPrice>
    <city type="string">Paris</city>
    <country type="string">US</country>
    <geoPoint class="array">
     <e type="number">48.86536</e>
     <e type="number">2.329584</e>
    </geoPoint>
    <hotelRateIndicator type="string">2</hotelRateIndicator>
    <id type="number">56263</id>
    <name type="string">Renaissance Paris Vendome Hotel</name>
    <neighborhood type="string" />
    <popularity type="number">837</popularity>
    <starRating type="string">5</starRating>
    <state type="string">IdF</state>
    <telephoneNumbers class="array">
     <e type="string" />
    </telephoneNumbers>
    <thumbnailUrl type="string">http://www.orbitz.com//public/hotelthumbnails/53/97/85397/85397_TBNL_1246535840051.jpg
    </thumbnailUrl>
    <total type="number">250</total>
    <ypid type="string">YN10001x300073304</ypid>
   </e>
   <e class="object">
    <addressLine1 type="string">39 Avenue de Wagram</addressLine1>
    <amenities class="array">
     <e type="string">24</e>
     <e type="string">31</e>
     <e type="string">42</e>
     <e type="string">9</e>
    </amenities>
    <brandCode type="string">69</brandCode>
    <cachedPrice type="number">633</cachedPrice>
    <city type="string">Paris</city>
    <country type="string">US</country>
    <geoPoint class="array">
     <e type="number">48.877106</e>
     <e type="number">2.297451</e>
    </geoPoint>
    <hotelRateIndicator type="string">3</hotelRateIndicator>
    <id type="number">112341</id>
    <name type="string">Renaissance Paris Arc de Triomphe Hotel</name>
    <neighborhood type="string" />
    <popularity type="number">796</popularity>
    <starRating type="string">5</starRating>
    <state type="string">IdF</state>
    <telephoneNumbers class="array">
     <e type="string" />
    </telephoneNumbers>
    <thumbnailUrl type="string">http://www.orbitz.com//public/hotelthumbnails/21/72/302172/302172_TBNL_1246535872514.jpg
    </thumbnailUrl>
    <total type="number">250</total>
    <ypid type="string">YN10001x300073331</ypid>
   </e>
   <e class="object">
    <addressLine1 type="string">35 Rue de Berri</addressLine1>
    <amenities class="array">
     <e type="string">24</e>
     <e type="string">31</e>
     <e type="string">42</e>
     <e type="string">9</e>
    </amenities>
    <brandCode type="string">82</brandCode>
    <cachedPrice type="number">706</cachedPrice>
    <city type="string">Paris</city>
    <country type="string">US</country>
    <geoPoint class="array">
     <e type="number">48.873684</e>
     <e type="number">2.306411</e>
    </geoPoint>
    <hotelRateIndicator type="string">3</hotelRateIndicator>
    <id type="number">108606</id>
    <name type="string">Crowne Plaza Hotel PARIS-CHAMPS ELYSÉES</name>
    <neighborhood type="string" />
    <popularity type="number">796</popularity>
    <starRating type="string">5</starRating>
    <state type="string">IdF</state>
    <telephoneNumbers class="array">
     <e type="string" />
    </telephoneNumbers>
    <thumbnailUrl type="string">http://www.orbitz.com//public/pegsimages/CP/thumb_PARAT.jpg
    </thumbnailUrl>
    <total type="number">250</total>
    <ypid type="string">YN10001x300161106</ypid>
   </e>
   </hotels>
 </e>
</a>   


XMLsample.java

In this code I have used DOM parser and xpath java library to query xml document. Here I am trying to extract hotel information[Hotel name, geo codes, star rating] from xmlfile.xml document

package com.eviac.blog;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathExpression;
import javax.xml.xpath.XPathFactory;

import org.w3c.dom.Document;
import org.w3c.dom.NodeList;

public class XMLsample {

 public static void main(String[] args) {

  try {
   // loading the xml document into DOM Document object
   DocumentBuilderFactory domFactory = DocumentBuilderFactory.newInstance();
   domFactory.setNamespaceAware(true);
   DocumentBuilder builder = domFactory.newDocumentBuilder();
   Document doc = builder.parse("xmlfile.xml");

   // XPath object using XPathFactory
   XPath xpath = XPathFactory.newInstance().newXPath();
   
   // XPath Query, compiling the path using the compile() method
   XPathExpression expr = xpath.compile("//hotels/e/name | //hotels/e/starRating | //hotels/e/geoPoint/e/text()");
   Object result = expr.evaluate(doc, XPathConstants.NODESET);
   NodeList nodes = (NodeList) result;
   for (int i = 0; i < nodes.getLength(); i++) {
    System.out.println(nodes.item(i).getTextContent());
   }
  } catch (Exception e) {
   e.printStackTrace();
  }
 }
}


Output
48.86536
2.329584
Renaissance Paris Vendome Hotel
5
48.877106
2.297451
Renaissance Paris Arc de Triomphe Hotel
5
48.873684
2.306411
Crowne Plaza Hotel PARIS-CHAMPS ELYS√ČES
5