Using Yahoo Query Language in Liferay(YQL)

Yahoo Query Language (YQL)

The Yahoo Query Language is an expressive SQL-like language that lets you query, filter, and join data across Web services. With YQL, apps run faster with fewer lines of code and a smaller network footprint.

Download Liferay YQL portlet from following location

You can find source and war file

https://sourceforge.net/projects/meeralferay/files/LiferayYQLPortlet/

Note: Portlet developed in Liferay 6.1GA2 EE version

If you want deploy in CE version you just do changes in liferay-plugin-package.properties

Liferay 6.1 EE version

name=LiferayYQL

module-group-id=liferay-ee

module-incremental-version=1

tags=

short-description=

change-log=

page-url=http://www.liferay.com

author=Liferay, Inc.

licenses=EE

liferay-versions=6.1.20

Liferay 6.1 CE version

name LiferayYQL

module-group-id=liferay

module-incremental-version=1

tags=

short-description=

change-log=

page-url=http://www.liferay.com

author=Liferay, Inc.

licenses=LGPL

liferay-versions=6.1.1

Understanding YQL:

Yql provide syntax’s like sql so that we can fetch data from yahoo web services.

We already know about web service like SOAP and REST but YQL is very simple to use in web sites.

This is very special language to yahoo to fetch yahoo data .

But we can also provide our data available to YQL using data tables.

The following scenarios we can use YQL

Fetch Weather Information
Fetch Stock Market Information Up to date
Currency conversion
Fetch yahoo news

How to use YQL:

Open Yahoo console from fowling URL

http://developer.yahoo.com/yql/console/

Select any tables which are left side

Select any tables it will populate sample query in console text box

You can click on Test button and see the result.

Here YQL provide to kinds of data JSON and XML before click on test button you can select any of formats then data will be showed in result part.

Once the result is desirable then copy the URL which showed in bottom this URL can be used to get content.

Once get content you can display into your website

Example:

Lets us assume we want display weather information in our web site:

Go to Yahoo console

http://developer.yahoo.com/yql/console/

Execute following YQL query

select * from weather.forecast where location=90210

Select JSON and Test

In the result you can see the data related to weather you can identify json or xml structure and retrieve in website.

We can use YQL in different ways:

I suggest you use two ways

YUI YQL java script library

Simple jquery AJAX

YUI YQL java script library:

To use YQL in your application first we need following YQL and YUI library

And use YUI use method and add required modules we need to add yql module when we work with YQL

The following is complete code

YUI().use('node','yql', function(Y) {

var res = Y.one('#res');

var woeid = '2502265';

Y.YQL('select * from weather.forecast where woeid='+woeid, function(r) {

var el = Y.Node.create('<div class="mod"></div>');

el.set('innerHTML', '<h2>Weather for ' + zip + '</h2>' + r.query.results.channel.item.description);

res.set('innerHTML',r.query.results.channel.item.description);

});

</script>

<div id="res">Weather Info Here</div>

Simple jquery AJAX:

We can also used jquey Ajax to execute YQL queries

Generally All YQL queries requested by following URL

http://query.yahooapis.com/v1/public/yql

We need to pass following parameters to above URL

q : the YQL query which you desire

format: type of data xml or json

env: env is type of parameter which specified where data table are available

For more info we need read about data tables

diagnostics: is Boolean value it will give error information in response if anything fails

callback: is optional parameter

The following is example:

http://query.yahooapis.com/v1/public/yql?q=select * from weather.forecast where woeid=2502265&format=json&diagnostics=true&env=http://datatables.org/alltables.env&callback=

Note:

When we execute any YQL statement in YQL console for each statement we will gate URL in the bottom

If see URL you can identify url and its query string but here all parameters are encoded format.

For know what parameters using you yql statement you can decode URL. The following is URL decoding in online.

http://www.url-encode-decode.com/

$(document).on('ready',function(){

var weatherQuery='select * from weather.forecast where woeid=2502265’

$.ajax({

url: 'http://query.yahooapis.com/v1/public/yql',

dataType:"json",

data: {

q:weatherQuery,

format:"json",

diagnostics:"true",

env:"http://datatables.org/alltables.env",//env:"store://datatables.org/alltableswithkeys",

callback:""

type: "get",

success: function(r){

$('#res').html(r.query.results.channel.item.description);

beforeSend: function(){

complete: function(){

error: function(){

}

});

</script>

<div id="res">Weather Info Here</div>

YQL can fetch against yahoo web services

The following are some information about data tables

You can see all tables and execute query in YQL console and find the data structure and use

Get Stocks quotes information:

Table: yahoo.finance.quotes

Query: select * from yahoo.finance.quotes where symbol in ("YHOO","AAPL","GOOG","MSFT")

Get Stock Market Indexes

Table: yahoo.finance.quoteslist/ yahoo.finance.quotes

Query: select * from yahoo.finance.quotes where symbol in ("^hsi","^bsesn","^nsei","^dji","^ixic")

Get Top Stories from news table:

Table: yahoo feed

Query: select * from feed where url='http://news.yahoo.com/rss/topstories'

Get Weather Organization ID(Weoid) from Longitude and Latitude

Table: geo.placefinder

Query: select * from geo.placefinder where text="22.2500,114.1667" and gflags="R"

For more info about gflags: http://developer.yahoo.com/boss/geo/docs/control-parameters.html

Get Weather Organization ID(Weoid) from Address

Table: geo.placefinder

Query: select * from geo.placefinder where text='Central,Honk Kong' and gflags='R'

WE can also fetch html from websites using YQL

If some time we did not find any web services simple from web page you can fetch data and you can filter the content.

Here in where condition we need to pass xpathnotation

Fetch some use full data from Yahoo finance page like all Stock indexes

select * from html where url="http://finance.yahoo.com/" and xpath='//div[@class="desc"]'

select * from html where url="http://finance.yahoo.com/q?s=yhoo" and

xpath='//div[@id="yfi_headlines"]/div[2]/ul/li/a'

Note:

We can open page and identify the required content from page using Chrome inspect element option.

Find the xpath of content and apply to YQL.

Important Points:

YQL is like sql statements to fetch content from yahoo web services.
These all information they provided as data tables. So that we can use YQL against data tables to fetch the content.
YQL provide xml and JSON formats.
Each YQL statement can be provided as web URL so that we can directly execute in browser and see the result.
To fetch the content from data table yahoo provides one URL and we need to use that public URL and pass some query parameter to get result. By this we can send Ajax calls.
Yahoo provide special module YQL module from their java script library i.e. YUI.
We can use YUI yql library to get content from data tables.
YQL very convenient way to use in web site because we can use this with java script libraries like jquery,YUI or other java script libraries.
YQL also provide way to fetch html content for web page as json or xml format so that we can use this data in website this scenarios happen when we don’t have web services.

Reference Links

YQL tutorial

http://yuilibrary.com/yui/docs/yql/

YQL console

http://developer.yahoo.com/yql/console/

YQL complete tutorial

http://developer.yahoo.com/yql/

Data Tables

http://developer.yahoo.com/yql/guide/yql-opentables-chapter.html

Xpath tutorial:

http://www.w3schools.com/xpath/

Online URL encodes and decodes:

http://www.url-encode-decode.com/

Author: Meera Prince

About Meera Prince

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Using Yahoo Query Language in Liferay(YQL)