The Google Documents List API allows client applications to view and manipulate files in a user’s Documents List.

In this blog we would learn how to share documents and files between the Google Apps Domain.

When our application requests non-public user data, it must include an authorization token. The token also identifies your application to Google. Requests to the Google Documents List Data API for non-public user data must be authorized by an authenticated user. Here, OAuth authorization is used to authorize Documents List Data API as following:

name='docs';
scope='https://docs.google.com/feeds/';
function googleOAuth_(name,scope) {
  var oAuthConfig = UrlFetchApp.addOAuthService(name);
  oAuthConfig.setRequestTokenUrl("https://www.google.com/accounts/OAuthGetRequestToken?scope="+scope);
  oAuthConfig.setAuthorizationUrl("https://www.google.com/accounts/OAuthAuthorizeToken");
  oAuthConfig.setAccessTokenUrl("https://www.google.com/accounts/OAuthGetAccessToken");
  oAuthConfig.setConsumerKey(consumerKey);
  oAuthConfig.setConsumerSecret(consumerSecret);
  return {oAuthServiceName:name, oAuthUseToken:"always"};
}

Document and collection sharing is controlled via the access control list feed. Access control lists are just basic lists that show who has access to a given resource. In the ACL feed, different type of roles scopes are available for a given document or folder.

Document’s resource_id is required to share any document with other. Resource_id is the alphanumeric key, which shows in the url as ‘/d/<…resource_id…>/’. Authenticated user’s documents and files’s resource_id can be accessed by sending an authorized GET request as following:

var url = 'https://docs.google.com/feeds/<user_email_id>/private/full?v=3&alt=json';
var urlFetchResult = UrlFetchApp.fetch(url, fetchArgs);

The result is a feed that lists the user’s documents and files, each entry in the feed represents a resource associated with the user.
We can get particular docs’s resource_id by parse the json result. Then use split() to get document’s resource_id in each entry as follow:

var json = Utilities.jsonParse(urlFetchResult.getContentText());
var entry = json.feed.entry;
for(var i in entry){
  var docId = {};
  for(var j in entry[i]){
    tempDoc.id = entry[i].id.$t.split('%3A')[1];
  }

Post the following request to share document with user:

POST https://docs.google.com/feeds/<user_email_id>/private/full/resource_id/acl
Authorization: <your authorization header here>

<entry xmlns="http://www.w3.org/2005/Atom" xmlns:gAcl='http://schemas.google.com/acl/2007'>
<category scheme='http://schemas.google.com/g/2005#kind'
term='http://schemas.google.com/acl/2007#accessRule'/>
<gAcl:role value='<role_type>'/>
<gAcl:scope type='<scope>' value='<user2_email_id>'/>
</entry>

Here is the complete code:

var consumerKey='<domain_name>'
var consumerSecret='<domain_consumerSecret_key>'
var user1='<email_id>'  //Email_Id of the person, whose docs would be shared
var user2='<email_id>' //Email_Id of the person,to whom docs would be share

function DocumentSharing(){

  var base = 'https://docs.google.com/feeds/';
//oAuth
  var fetchArgs = googleOAuth_('docs', base);
  var url = base + user1+'/private/full?v=3&alt=json';
  var urlFetchResult = UrlFetchApp.fetch(url, fetchArgs);
  var json = Utilities.jsonParse(urlFetchResult.getContentText());
  var entry = json.feed.entry;
  var docs = [];

  fetchArgs.method = 'POST';
  var rawXml = "<entry xmlns='http://www.w3.org/2005/Atom' xmlns:gAcl='http://schemas.google.com/acl/2007'>"
  +"<category scheme='http://schemas.google.com/g/2005#kind' "
  +"term='http://schemas.google.com/acl/2007#accessRule'/>"
  +"<gAcl:role value='writer'/>"
  +"<gAcl:scope type='user' value='"+user2+"'/>"
  +"</entry>";
  fetchArgs.payload = rawXml;
  fetchArgs.contentType = 'application/atom+xml';

  for(var i in entry){
    var tempDoc = {};
    for(var j in entry[i]){
      tempDoc.id = entry[i].id.$t.split('%3A')[1];
      tempDoc.title = entry[i].title.$t;
    }
    docs.push(tempDoc);
    var url = base + user1+'/private/full/'+docs[i].id+'/acl?v=3&alt=json';
    try{
      var urlFetch = UrlFetchApp.fetch(url, fetchArgs);
    }
    catch(err){
      MailApp.sendEmail(user2,docs[i].title+"("+user2+")","",
      {htmlBody:"This user already has access to document   <b>"+docs[i].title+"</b>"})
    }
  }
}

//Google oAuth
function googleOAuth_(name,scope) {
  var oAuthConfig = UrlFetchApp.addOAuthService(name);
  oAuthConfig.setRequestTokenUrl("https://www.google.com/accounts/OAuthGetRequestToken?scope="+scope);
  oAuthConfig.setAuthorizationUrl("https://www.google.com/accounts/OAuthAuthorizeToken");
  oAuthConfig.setAccessTokenUrl("https://www.google.com/accounts/OAuthGetAccessToken");
  oAuthConfig.setConsumerKey(consumerKey);
  oAuthConfig.setConsumerSecret(consumerSecret);
  return {oAuthServiceName:name, oAuthUseToken:"always"};
}

This script would share your all documents and files with another user. It also sends a notification mail to user (to whom docs is shared). If that user already accessed that document , a 409 server error would occurred. Here, try-catch is used to resolve this problem.

To know more about it Click Here