Get Google contacts with OAuth 2.0

Although neither POP3 nor IMAP protocol allows retrieving the list of user’s contacts, it is possible to use Google API for that.

As long as you are using one of OAuth 2.0 scenarios:

• OAuth 2.0 with Gmail over IMAP for web applications
• OAuth 2.0 with Gmail over IMAP for installed applications
• OAuth 2.0 with Gmail over IMAP for service account

Mail.dll email component allows you to easy download Gmail contacts of a particular user.

Turn on Contacts API

Remember to turn on “Contacts API” in Google management console.

Remember to add request for calendar data access using GoogleScope.ContactsScope.

// C#

List<GoogleScope> scope = new List<GoogleScope>
    {
        GoogleScope.ImapAndSmtp.Name,
        GoogleScope.EmailScope,
        GoogleScope.ContactsScope
    };

' VB.NET

Dim scope As New List(Of GoogleScope)() { _
    GoogleScope.ImapAndSmtp.Name, _
    GoogleScope.EmailScope, _
    GoogleScope.ContactsScope _
}

// C#

GoogleApi api = new GoogleApi(accessToken);

XmlDocument contacts = api.GetContacts();

XmlNamespaceManager nsmgr = new XmlNamespaceManager(contacts.NameTable);
nsmgr.AddNamespace("gd", "http://schemas.google.com/g/2005");
nsmgr.AddNamespace("a", "http://www.w3.org/2005/Atom");

foreach (XmlNode contact in contacts.GetElementsByTagName("entry"))
{
    XmlNode title = contact.SelectSingleNode("a:title", nsmgr);
    XmlNode email = contact.SelectSingleNode("gd:email", nsmgr);

    Console.WriteLine("{0}: {1}", 
        title.InnerText, 
        email.Attributes["address"].Value);
}

' VB.NET

Dim api As New GoogleApi(accessToken)

Dim contacts As XmlDocument = api.GetContacts()

Dim nsmgr As New XmlNamespaceManager(contacts.NameTable)
nsmgr.AddNamespace("gd", "http://schemas.google.com/g/2005")
nsmgr.AddNamespace("a", "http://www.w3.org/2005/Atom")

For Each contact As XmlNode In contacts.GetElementsByTagName("entry")
	Dim title As XmlNode = contact.SelectSingleNode("a:title", nsmgr)
	Dim email As XmlNode = contact.SelectSingleNode("gd:email", nsmgr)
	Console.WriteLine("{0}: {1}", _
            title.InnerText, _
            email.Attributes("address").Value)
Next

Tags: Email component Gmail OAuth 2.0