{"id":13634,"date":"2014-05-13T14:20:50","date_gmt":"2014-05-13T08:50:50","guid":{"rendered":"http:\/\/www.tothenew.com\/blog\/?p=13634"},"modified":"2016-12-19T15:07:33","modified_gmt":"2016-12-19T09:37:33","slug":"grails-way-of-oauth-2-0-to-access-google-apis-part-1","status":"publish","type":"post","link":"https:\/\/www.tothenew.com\/blog\/grails-way-of-oauth-2-0-to-access-google-apis-part-1\/","title":{"rendered":"OAuth 2.0 using Grails Part – 1"},"content":{"rendered":"

Following steps need to be followed for OAuth 2.0 authentication :<\/p>\n

(1) Obtain OAuth 2.0 credentials from the Google Developers Console:<\/h3>\n

<\/br>
\nFirst you need to have a google account. create a project at Google Developers Console<\/a> after logging into your Google account. Click on the project name go to “APIs and auth” click on credentianls and then create a client ID. You will get client id and client secret which is required for OAuth 2.0 authentication . You also need to add Javascript origin and redirect URI’s by clicking on edit settings.<\/p>\n

Let us assume javascript origin is “http:\/\/localhost:8080\/”
\nand redirect URI is “http:\/\/localhost:8080\/TestOAuth\/google\/success”
\n<\/br><\/p>\n

(2) Get authorization code.<\/h3>\n

<\/br>
\nFirst you need to obtain authorization code in order to get the access token.
\nYou need to have a link where a user can click to initiate the process of OAuth 2.0
\nThe link should be as follows:<\/p>\n

[html]<\/p>\n

<a href="https:\/\/accounts.google.com\/o\/oauth2\/auth?redirect_uri=http%3A%2F%2Flocalhost:8080%2FTestOAuth%2Fgoogle%2Fsuccess
\n &
\nresponse_type=code
\n&
\nclient_id={your client id}
\n&
\nscope=https%3A%2F%2Fwww.googleapis.com%2Fauth%2Fuserinfo.profile
\n&
\napproval_prompt=force
\n&
\naccess_type=offline"> SignInWithGoogle <\/a><\/p>\n

[\/html]<\/p>\n

After clicking on the above link you need to login using google account . After logging in you will be redirected to “http:\/\/localhost:8080\/TestOAuth\/google\/success?code={authorization code}”<\/p>\n

You can get the authorization code token from Querystring
\n<\/br><\/p>\n

(3) Exchange authorization code for access token<\/h3>\n

<\/br>
\nPlace the following line in BuildConfig.groovy<\/p>\n

[java]
\nplugins {
\nruntime ":rest:0.7"
\n}
\n[\/java]<\/p>\n

This plugin is required to make Get and POST Requests<\/p>\n

In the GoogleController.groovy we need to have a success action as follows:<\/p>\n

[java]
\ndef success(String code) {
\n String googleaccesstoken = ""
\n JSONObject googleJsonResponseForAccessToken
\n def http = new HTTPBuilder(‘http:\/\/localhost:8080\/’)
\n http.request(POST) {
\n uri.path = "https:\/\/accounts.google.com\/o\/oauth2\/token"
\n requestContentType = "application\/x-www-form-urlencoded"
\n body = [code: "${code}",
\n client_id: "{Client ID}",
\n client_secret: "{Client Secret}",
\n redirect_uri: "http:\/\/localhost:8080\/TestOAuth\/google\/success",
\n grant_type: "authorization_code"]<\/p>\n

response.success = { resp, json ->
\n println "POST response status: ${resp.statusLine}"
\n googleJsonResponseForAccessToken = json
\n googleaccesstoken = json.access_token
\n }
\n }<\/p>\n

}<\/p>\n

[\/java]<\/p>\n

In the above code we are making a POST request to and in response we will get following json<\/p>\n

[java]
\n{
\n"access_token": {access_token},
\n"token_type": "Bearer",
\n"expires_in": 3600,
\n"refresh_token": {refresh_token},
\n"id_token": {id_token}
\n}
\n[\/java]<\/p>\n

This response is stored in json object of response.success method in the above code . we have stored the value of access_token in variable “googleaccesstoken” in the code above.
\n<\/br><\/p>\n

(4) Get UserInfo from access_token<\/h3>\n

<\/br>
\nTo get the information of the user you need to make following request:<\/p>\n

[java]
\nJSONObject userInfo
\nhttp.request(GET) {
\n uri.path = "https:\/\/www.googleapis.com\/userinfo\/v2\/me"
\n uri.query = [accesstoken:googleaccesstoken]
\n headers.’Authorization’="Bearer ${googleaccesstoken}"
\n response.success = { resp, json ->
\n println "Get response status: ${resp.statusLine}"
\n userInfo=json
\n }
\n }
\n render "User Name :: "+userInfo.name
\n render "User Id :: "+userInfo.id<\/p>\n

[\/java]<\/p>\n

In the above code we have used the access_token which we got from the json response in step (3)<\/p>\n","protected":false},"excerpt":{"rendered":"

Following steps need to be followed for OAuth 2.0 authentication : (1) Obtain OAuth 2.0 credentials from the Google Developers Console: First you need to have a google account. create a project at Google Developers Console after logging into your Google account. Click on the project name go to “APIs and auth” click on credentianls […]<\/p>\n","protected":false},"author":102,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"iawp_total_views":18,"footnotes":""},"categories":[7],"tags":[4840,9,1160],"class_list":["post-13634","post","type-post","status-publish","format-standard","hentry","category-grails","tag-grails","tag-groovy","tag-oauth2-0"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t