There are basically 3 steps to fetch data from Google.

1. Register an application.

We need to register an application at Google API Console. Go to the Google console page using the link provided and create an aplication.

Steps involve in registering an application are:-

a.) Create project by providing name to the project.

b.) Turn ON the service required, in our case it is Google Plus API.

c.) Create a Oauth 2.0 Client ID.

d.) Create the OAuth 2.0 ClientId and provide the callback URL where google will send the authorization token.

e.) Note down Client ID and Client Secret as generated in the above step.

2. Obtain an Access Token from the Google Authorization Server.

Obtaining an access token involves 2 steps.

a.) Request for Authorization Code.

In this step, we will request the Google server for authorization code by providing registered application client ID in the URL to Google server.

I created an action to redirect to Goolge, when someone want to connect to google plus.

String CLIENT_ID =client_id_obtained from registered app
String CALLBACK_URL = callback_url_as_mentioned in the registered app.
String GOOGLE_PLUS_SCOPE='https://www.googleapis.com/auth/plus.me'    // scope is the permissions we are requesting.

Action code is as:

def registerOnGooglePlus = {
String authorizeUrl = "https://accounts.google.com/o/oauth2/auth?scope=${GOOGLE_PLUS_SCOPE}&
redirect_uri=${CALLBACK_URL}&response_type=code&client_id=${CLIENT_ID}&access_type=offline"
URL urlForGooglePlus = new URL(authorizeUrl)
redirect(url: urlForGooglePlus)
}

The Redirect will take user to permissions page, if the user is already logged-in or will take to login page and then permissions page.

After approving the required permissions, user will redirect back to the application’s registered Callback URL with the authorization code.

b.) Request for Access Token with the authorization code obtained from the above action.

Access Token can be received by a POST request using the Client Secret and authorization code received.

The POST call requires 5 properties to be send in the body of the request in the encoded form.

	code : The authorization code returned from the initial request
	client_id : The client_id obtained during application registration
	client_secret : The client secret obtained during application registration
	redirect_uri : The URI registered with the application
	grant_type : authorization_code

// Sample action to receive authorization code

def callBack={
StringBuilder sb = new StringBuilder("code=");
sb.append(URLEncoder.encode(code, "UTF-8"));
sb.append("&client_id=");
sb.append(URLEncoder.encode(clientId, "UTF-8"));
sb.append("&client_secret=");
sb.append(URLEncoder.encode(clientSecret, "UTF-8"));
sb.append("&redirect_uri=");
sb.append(URLEncoder.encode(callbackUrl, "UTF-8"));
sb.append("&grant_type=");
sb.append(URLEncoder.encode('authorization_code', "UTF-8"));

String URL_TO_REQUEST_TOKEN= 'https://accounts.google.com/o/oauth2/token'

URL url = new URL(URL_TO_REQUEST_TOKEN);
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
try {
connection.setRequestMethod("POST");
connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
connection.setRequestProperty("Content-Length", "" + sb.toString().length());
connection.setRequestProperty("Host", "accounts.google.com");
OutputStreamWriter outputStreamWriter = new OutputStreamWriter(connection.getOutputStream());
outputStreamWriter.write(sb.toString());
outputStreamWriter.flush();
log.debug("Response code ${connection.responseCode} , Message : ${connection.responseMessage}")
String resultData = connection.content.text
def responseJson = JSON.parse(resultData)
String ACCESS_TOKEN = responseJson?.access_token
}
catch (Exception e) {
e.printStackTrace()
}
}

3. Calling Google API.

Now, with the help of access token, we can call google API to fetch Data by appending the access token in the GET request.

Example:

To fetch person’s profile data

GET :  https://www.googleapis.com/oauth2/v1/userinfo?access_token=ACCESS_TOKEN

To get list of profile acitivties

 GET :  https://www.googleapis.com/plus/v1/people//activities/public?access_token=ACCESS_TOKEN

References:-
http://code.google.com/apis/accounts/docs/OAuth2WebServer.html

http://code.google.com/apis/accounts/docs/OAuth2.html

Hope this helps..!!!

Vishal Sahu
vishal[at]intelligrape[dot]com
www.intelligrape.com

The class has been named GoogleAjaxSearch because it uses the Google AJAX Search API

//Case 1 Simple Search
String searchQuery = "my search Query"
GoogleAjaxSearch googleAjaxSearch = new GoogleAjaxSearch(searchQuery)
println googleAjaxSearch.results //Type List<Expando>, Just print it to see available properties

//Case 2: Get Number Of Indexed Pages in Google
String searchQuery = "site:intelligrape.com"
GoogleAjaxSearch googleAjaxSearch = new GoogleAjaxSearch(searchQuery)
println googleAjaxSearch.estimatedResultCount

//Case 3: Redo a search with same SearchQuery or a different Search Query
String searchQuery = "search string"
GoogleAjaxSearch googleAjaxSearch = new GoogleAjaxSearch(searchQuery)
googleAjaxSearch.redo() //Re-Search with same query
googleAjaxSearch.redo("New Query") // Re-Search With New Query

//Case 4: All Details Available
String searchQuery = "site:intelligrape.com"
GoogleAjaxSearch googleAjaxSearch = new GoogleAjaxSearch(searchQuery)
println googleAjaxSearch.estimatedResultCount //Gives the result count, indexed pages count
println googleAjaxSearch.currentPageIndex    //Search result server side pagination - current page
println googleAjaxSearch.results  //List<Expando> containing results
println googleAjaxSearch.responseStatus //HTTP Status Code
println googleAjaxSearch.responseDetails //Details for response, if any
println googleAjaxSearch.searchQuery     //Search Query
println googleAjaxSearch.moreResultsUrl // Url to hit for next Page of results
println googleAjaxSearch.jsonResult // Complete raw JSON Result from google
println googleAjaxSearch.pages  // Pagination Pages Details

The Class Code Is As Follows:

package myPackage.googleSearch

import grails.converters.JSON

class GoogleAjaxSearch {

    public String searchQuery
    public String responseDetails
    public String moreResultsUrl
    public String jsonResult

    public Integer responseStatus
    public Integer currentPageIndex
    public Integer estimatedResultCount

    public def pages

    public List<Expando> results = []

    private static final String ajaxSearchTarget = "http://ajax.googleapis.com/ajax/services/search/web?v=1.0&q=###SEARCHQUERY###&filter=0"

    public GoogleAjaxSearch(String searchQuery) {
        this.searchQuery = searchQuery
        search()
    }

    public GoogleAjaxSearch() {
        this(null)
    }

    public void redo() {
        search()
    }

    public void redo(String newSearchQuery) {
        this.searchQuery = newSearchQuery
        search()
    }

    private void search() {
        if (searchQuery) {
            URL url = new URL(ajaxSearchTarget.replace('###SEARCHQUERY###', searchQuery))
            URLConnection connection = url.openConnection()
            connection.setDoInput(true)
            InputStream inStream = connection.getInputStream()
            BufferedReader searchResultContent = new BufferedReader(new InputStreamReader(inStream))
            jsonResult = searchResultContent.getText()
            parseJsonAndPopulateObject()
        }
    }

    private void parseJsonAndPopulateObject() {
        def jsonArray = JSON.parse(jsonResult)
        this.responseStatus = Integer.parseInt(jsonArray.responseStatus as String, 10)
        this.responseDetails = jsonArray.responseDetails
        this.moreResultsUrl = jsonArray.responseData.cursor.moreResultsUrl
        this.currentPageIndex = Integer.parseInt(jsonArray.responseData.cursor.currentPageIndex as String, 10)
        this.pages = jsonArray.responseData.cursor.pages
        this.estimatedResultCount = Integer.parseInt(jsonArray.responseData.cursor.estimatedResultCount as String, 10)
        results = jsonArray.responseData.results.collect {
            new Expando(
                    content: it.content,
                    GsearchResultClass: it.GsearchResultClass,
                    titleNoFormatting: it.titleNoFormatting,
                    title: it.title,
                    cacheUrl: it.cacheUrl,
                    unescapedUrl: it.unescapedUrl,
                    url: it.url,
                    visibleUrl: it.visibleUrl
            )
        }
    }
}

Hope That Helps
Regards
Kushal Likhi

All the projects I have worked on had login functionality where we put the userId and projectId into the session. Then in my code I use to get the user from session.userId. Something like

def books = {
   User user = User.get(session.userId)
   Project project = Project.get(session.projectId)
   ......
   .....
}

The above code fails when user directly hits this action because there is no check to verify the user is not null. The simple answer for this problem is either use beforeInterceptor or filters. So we started checking the session.userId in filters. But again there are cases where you dont want to check this session value or you can say there are public urls as well. Now we have to put few if else statements in filter.

Here I got my use case to implement an annotation for controllers and actions which checks for the required fields in the session before getting into the action. So I created an annotation in src/groovy folder

import java.lang.annotation.ElementType
import java.lang.annotation.Retention
import java.lang.annotation.RetentionPolicy
import java.lang.annotation.Target

@Target([ElementType.FIELD, ElementType.TYPE]) // Annotation is for actions as well as controller so target is field and for class
@Retention(RetentionPolicy.RUNTIME) // We need it at run time to identify the annotated controller and action
@interface RequiredSession {
    String[] exclude() default [] // To exclude some of the actions of controller

    String[] fields() default ["userId","projectId"] // The default value is set to userId and projectId that can be overridden while using the   annotation on controller or action.

    String onFailController() default "home" // Default controller when the field not in session is set to index page

    String onFailAction() default "index" // Default action when the field not in session is set to index page
}

Now I created a ApplicationFilters and before redirected the request to any action I check for the condition of session fields if the requested action or controller is annotated. The code in the filter is something like

class ApplicationFilters {
    def filters = {
        validateSession(controller: '*', action: '*') {
            before = {
                if (controllerName) {

//Get the instance of controller class from string value i.e; controllerName
                    def controllerClass = grailsApplication.controllerClasses.find {it.logicalPropertyName == controllerName}

//Read the RequiredSession annotation from controller class
                    def annotation = controllerClass.clazz.getAnnotation(RequiredSession)

//Get the current action from actionName otherwise read default action of controller
                    String currentAction = actionName ?: controllerClass.defaultActionName

//Look for the annotation on action if controller is not annotated or the action name is excluded
                    if (!annotation || currentAction in annotation.exclude()) {

//Get the action field from string value i.e; currentAction
                        def action = applicationContext.getBean(controllerClass.fullName).class.declaredFields.find { field -> field.name == currentAction }
//If action is found get the annotation else set it to null
                        annotation = action ? action.getAnnotation(RequiredSession) : null
                    }

//Check for the field in session whether the are null or not if any of the field is null loginFailed is true
                    boolean loginFailed = annotation ? (annotation.fields().any {session[it] == null}) : false

                    if (loginFailed) {

// If login is failed user redirected to on fail action and controller
                        redirect(action: annotation.onFailAction() , controller: annotation.onFailController())
                        return false;
                    }
                }
            }

        }
    }
}

And its all done. Now we just annotate our controller and actions accordingly.

@RequiredSession(exclude = ["registration", "joinProject"])
class UserController {
      def edit ={}
      def update = {}
      def list ={}
      def save ={}

      def registration ={}
      def joinProject = {}
}

In above example registration and joinProject action will bypass the session fields check.

@RequiredSession
class ItemController {
        def index={}
        def buy ={}
        def save ={}
}

All the action of above examples can be accessed only when user is logged in.

class HomeController {
      def index ={}
      def aboutUs={}
      @RequiredSession
      def dashboard = {}
}

Actions other than dashboard are public actions which can be accessed without login.

class UserController {
  @RequiredSession(fields = ["loggedInUserId"])
   def updatePassword = {

   }
}

For updating password user dont need to have some project into session so we specified the fields to be checked in session.

Hope it helps

## Uday Pratap Singh ##
uday@intelligrape.com
http://www.IntelliGrape.com/
http://in.linkedin.com/in/meudaypratap

In one of my recent grails project, i needed to set System property from command line while running the grails application.
I looked for it and found a simple solution to do so and found it worth sharing.


Suppose we want to set any property, say app.property=”propertyValue”, then the command to set the property in grails application would be:

  grails  -Dapp.property="propertyValue" run-app

Similarly to retrieve the value of System property, we use

String myPropertyValue= System.getProperty("app.property")

It helped me a lot..
Hope it helps


Vishal Sahu
vishal@intelligrape.com
www.intelligrape.com

There are use cases where we need to show some errors which are beyond your domain / command object constraints validators for these cases you can inject your custom error messages to the object take an example of updating the password. Any of the field is not domain related so we have to create a command object like

class UpdatePasswordCO {

    String password
    String newPassword
    String confirmNewPassword

    static constraints = {
        password(nullable: false, blank: false)
        newPassword(nullable: false, blank: false)
        confirmNewPassword(nullable: false, blank: false, validator: {val,   obj ->
            if (obj.newPassword != val) {
                "confirmPassword.mismatch.newPassword"
            }
        })
    }
}

Now you have to check whether the logged in user entered the correct password or not. So rather than putting the message in flash scope you can directly put this error to the command object it self

def updatePassword = {UpdatePasswordCO updatePasswordCO ->
        if (updatePasswordCO.validate()) {
            if (User.loggedInUser.validatePassword(updatePasswordCO.password)) {
                flash.message = "Password updated successfully"
            } else {
                updatePasswordCO.errors.rejectValue("password", "password.mismatch.current.password")
            }
        }
        if (updatePasswordCO.hasErrors()) {
            render(view: 'profile', model: [updatePasswordCO: updatePasswordCO])
        } else {
            redirect(action: 'profile')
        }
}

So in above approach you have injected a new error on password field with a code. By doing this your hasErrors tag on gsp page will show your custom error as well. For more details you can refer Spring

Hope it helps


## Uday Pratap Singh ##
uday@intelligrape.com
http://www.IntelliGrape.com/
http://in.linkedin.com/in/meudaypratap

In one of my project i needed to generate EAN-8 standard bar-code for identifying the various products. I searched for various libraries available for generating bar-code and found a library to do so. The library i used for generating the bar-code is Barcode4J.
You can download it from here

Barcode4J is a flexible generator for barcodes written in Java. It’s free, available under the Apache License, version 2.0.
The bar-code generated with the help of of this library uses eight digit number hence EAN-8.

To generate bar-code image from this library is quite simple. Just put the barcode4j.jar in the lib folder of the application.

Code to generate image is:-

public File generateBarcode(Long codeDigits){
try {
      //'codeDigits' is the code for which we want to generate bar-code image
     EAN8Bean bean = new EAN8Bean();
     final int dpi = 150;
     bean.setModuleWidth(UnitConv.in2mm(1.0f / dpi));
     bean.setFontSize(2.0)
     bean.doQuietZone(true)
     File outputFile = new File(filepath) // existing file in the file system
     OutputStream out = new FileOutputStream(outputFile)

     // class to convert provided image into barcode image
     BitmapCanvasProvider canvas = new BitmapCanvasProvider(out, "image/jpeg", dpi,   BufferedImage.TYPE_BYTE_BINARY, false, 0)
     bean.generateBarcode(canvas, codeDigits)
     canvas.finish()
     return outputFile
}

So, here it takes a file from the file system and convert it into the required barcode image. Now, the user can simply display this image on the items.

In my case, i needed to generate a bar-code image for each product, so i create new file for every item, and stored it on the file system with unique name.

This works in my case.
Hope it helps

Cheers..!!!
Vishal Sahu
vishal@intelligrape.com

In my recent grails project, i needed to return back to the application after processing payment at the paypal website. I searched a lot about it. Then i found the solution to do so and thought it worth sharing.

Here are the steps i followed:-

1. The Paypal button:-
This is the code for putting the paypal button in any web-page

Here:
The email of merchant’s account or the seller account, the account to which payment is to be made and the email by which the account is registered is given in the hidden field “business”.

The URL to which we want application to return after processing payment is provided in the hidden field with the name “return” i.e.

This completes the application side implementation for paypal.

2. Paypal Account Configuration
Now we have to configure the Merchant’s account to Auto-redirect to the provided URL after processing the payment.

Steps to configure account are:-

1. Log in to Paypal Account
2. Click the Profile Link in sub-menu of My Account.


3. Under “Selling Preferences” click ‘Website Payment Preferences’ link.

4. Select the Auto-Return radio button to enable the auto return feature.

This enables the auto-redirect feature in the paypal account.

This worked for me.
Hope it helps.

Vishal Sahu
vishal@intelligrape.com

public Date convertToNewTimeZone(Date date, TimeZone oldTimeZone, TimeZone newTimeZone){

      long oldDateinMilliSeconds=date.time - oldtimeZone.rawOffset
      // oldtimeZone.rawOffset returns the difference(in milliSeconds) of time in that timezone with the time in GMT
      // date.time returns the milliseconds of the date

      Date dateInGMT=new Date(oldDateinMilliSeconds)

      long convertedDateInMilliSeconds = dateInGMT.time + newTimeZone.rawOffset
      Date convertedDate = new Date(convertedDateInMilliSeconds)

    return convertedDate
}

This Works for me.
Hope it helps.

Cheers..!!!
Vishal Sahu
vishal@intelligrape.com
www.intelligrape.com

But let’s say you have a List of objects that you want to sort on the basis of two fields. Let’s discuss it with an example.


I have a list of Tasks (with date and priority fields). I want to sort these tasks ordered by Date and priority-wise (as second level sorting).

Here, I gonna use Expando class, so I can directly run this in my groovyConsole. But definitely you can use some ‘Task’ class.

Expando a = new Expando(date: Date.parse('yyyy-MM-dd','2011-01-01'), priority:1)
Expando b = new Expando(date: Date.parse('yyyy-MM-dd','2011-01-01'), priority:2)
Expando c = new Expando(date: Date.parse('yyyy-MM-dd','2011-01-02'), priority:1)
Expando d = new Expando(date: Date.parse('yyyy-MM-dd','2011-01-01'), priority:3)

def list = [a,d,c,b]

If sorting was required on the basis of date only, it was very simple.

list.sort(it.date)

But as per our requirements – order by date (first level sorting) and priority (second level sorting). We can do something like following.

list.sort{x,y->
  if(x.date == y.date){
    x.priority <=> y.priority
  }else{
    x.date <=> y.date
  }
}

Well, there could be some better way. If you know please put your comments. But it worked well in my case.

Cheers!
Salil Kalia
Salil [at] IntelliGrape [dot] com
Twitter LinkedIn

I was facing a lot of problems with creating pdf reports using jasper plugin 1.1.6 in grails, Though I had earlier worked with 0.9.5 and 0.9.7 versions of the plugin with a lot of ease but some how 1.1.6 version of plugin was not generating reports  it always ended up throwing MalformedByteSequenceException: Invalid byte 1 of 1-byte UTF-8 sequence.

com.sun.org.apache.xerces.internal.impl.io.MalformedByteSequenceException: Invalid byte 1 of 1-byte UTF-8 sequence.
 at com.sun.org.apache.xerces.internal.impl.io.UTF8Reader.invalidByte(UTF8Reader.java:684)
 at com.sun.org.apache.xerces.internal.impl.io.UTF8Reader.read(UTF8Reader.java:554)
 at com.sun.org.apache.xerces.internal.impl.XMLEntityScanner.load(XMLEntityScanner.java:1742)
 at com.sun.org.apache.xerces.internal.impl.XMLEntityScanner.arrangeCapacity(XMLEntityScanner.java:1619)
 at com.sun.org.apache.xerces.internal.impl.XMLEntityScanner.skipString(XMLEntityScanner.java:1657)
 at com.sun.org.apache.xerces.internal.impl.XMLVersionDetector.determineDocVersion(XMLVersionDetector.java:193)
 at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:772)
 at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:737)
 at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(XMLParser.java:119)
 at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.parse(AbstractSAXParser.java:1205)
 at com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl$JAXPSAXParser.parse(SAXParserImpl.java:522)
 at org.apache.commons.digester.Digester.parse(Digester.java:1647)
 at net.sf.jasperreports.engine.xml.JRXmlLoader.loadXML(JRXmlLoader.java:241)
 at net.sf.jasperreports.engine.xml.JRXmlLoader.loadXML(JRXmlLoader.java:228)
 at net.sf.jasperreports.engine.xml.JRXmlLoader.load(JRXmlLoader.java:216)
 at net.sf.jasperreports.engine.JasperCompileManager.compileReport(JasperCompileManager.java:199)
 at net.sf.jasperreports.engine.JasperCompileManager$compileReport.call(Unknown Source)
 at net.sf.cglib.proxy.MethodProxy.invoke(MethodProxy.java:149)
 at java.lang.Thread.run(Thread.java:662)

I tried various things like changing the header of the jrxml file, adding new attributes in jasperReport tag and changing encoding type but to no Avail. Then I tried generating report without the .jasper files and deleted all jasper files except for sub-reports (sub-reports need to be in a pre-compiled state for the plugin to work)  and thing started working. For some strange reason the plugin was throwing exception when jasper report was available but if the report was compiled on the fly the plugin had no trouble with it. I am not sure what may be the reason may be I-report or something, but I got a move on. Hope You will too.

With Regards

Sachin Anand

sachin[at]intelligrape[dot].com