Classic ASP and Facebook Graph API

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Introduction

In a previous article I provided a set of utility functions for connecting your website to Facebook using the Facebook for Websites API. This article builds and improves upon the original app and adds some examples of how we can leverage Facebook's Graph API to provide deeper interaction with Facebook.

Background

This article will build on the same code from the previous article that has been refactored into a class object.

What is the Graph API?

The Graph API is Facebook's way of enabling automation of most UI functions based on a REST-ful interface.

The Graph API makes a request to Facebook at a URL that looks like this: http://graph.facebook.com/ID. The ID is the ID of the Facebook object you are working on. Every object in Facebook has an ID as required by REST. You can find the full set of documentation here: http://developers.facebook.com/docs/reference/api/.

Using the code

Before you use the code, you must create a Facebook Application and have an application ID and secret code. See the first article for details.

In this article, I'll provide the base patterns for working with Facebook data. The code will implement a consistent way of returning data from Facebook so when you access user.hometown (for example), it will always return a value or blank. It will not produce an error if the data is not returned by Facebook. Each function in the new design includes test pages that help verify the function works.

Refactoring the original code

Let's review how the current code differs from the previous article. The main change is that all but a few functions are encapsulated in a class library named fb_utility. The code block below shows the class structure for fb_utility.

''************************************************************
'' A summary of the fb_utility class as found in fb_app.asp
''************************************************************
class fb_utility
    dim dictKey 
    dim dictItem

    '' Initialize the fb_utility class
    sub Class_Initialize()
        '' Initialize KSort values
        dictKey  = 1
        dictItem = 2
    end sub

    '' get the contents of a web page, include 
    '' validation that the user is logged in
    public function get_page_contents(strURL)
    end function 
    

    '' Some Facebook API functions require a post
    '' this function handles the post request
    public function post_page(strURL, strData)
    end function 
    
    '' Generate a GUID
    public Function NewID()
    End Function        

    '' KSort is not required for the new oAuth
    '' however you might find it useful
    public function ksort(byref objDict )
        SortDictionary objDict, dictKey 
    end function
    
    '' Sort dictionary is called by the ksort function
    Function SortDictionary(byref objDict, intSort)
    End Function    
    
    '' gets the access token from the return 
    '' authentication request made to Facebook
    public function parse_access_token( str )
    end function

    '' Parses the expires value from the return data 
    '' provided after an oAuth request to Facebook
    '' I have yet to figure out how to make use of this
    public function parse_expires( str )
    end function
    
end class

This utility class is re-used by just about every other class and function in the Graph API and initial authorization functions.

The basic request pattern

For the most part, every Graph API request does some basic things: make a call to fb_utility.get_page_contents which returns a JSON string which is then converted to a JSON object for reference. The problem with data returned from Facebook is that if a value is blank or null, the property is not returned. For example: user.hometown might not be populated by the user you are requesting, as a result the JSON string returned by Facebook will not contain a hometown value. When the JSON string is converted to an object it will not have a hometown property. As a result, attempting to access user.hometown will trigger a VBScript error. I call it the "sparse data problem".

To solve the sparse data problem, I include a code block in each class that maps from JSON to a VBScript class to provide a reliable interface for each data object.

Below you will find a pattern for a Facebook Data Type Object implemented in a VBScript class. A call to Load and passing the Facebook Object ID will get the JSON string and a call to load_from_json_object will perform the mapping.

'' Copy and paste the template below for each new Facebook DTO class

'' A Facebook DTO
class fb_DTO

    '' **
    '' ** Declare Variables
    '' **
    
    '' Default Variables for properties 
    dim fbu '' Facebook utility object
    dim m_token ''
    dim m_json_str ''
    dim m_graph_url ''
    
    '' Default Internal Variables
    
    '' Object Type Specific Variables
    
    '' **   
    '' ** property exposure
    '' **

    
    '' Default Properties
    public property get graph_url()
        graph_url = m_graph_url
    end property
    
    public property get json_string()
        json_string = m_json_str
    end property
    
    public property get token()
        token = m_token
    end property
    public property let token(value)
        m_token = value
    end property
    
    
    '' Object Type property exposure
    
    '' initialization
    sub Class_Initialize
        set fbu = new fb_utility
    end sub
    
    '' termination
    sub Class_Terminate
        set fbu = nothing
   end sub

    '' **
    '' Implementation
    '' **
    
    '' Load object by id
    public sub Load(ID)
        dim obj
        
        m_graph_url = "https://graph.facebook.com/" & id & _
                      "?access_token=" & m_token 
        m_json_str = fbu.get_page_contents( m_graph_url )
        set obj = JSON.parse( m_json_str )
        load_from_json_object obj
    end sub
    
    public sub load_from_json_object( fb_obj )
    
        on error resume next
        '' map your properties here
        
        on error goto 0
        err.clear
    end sub
    
end class

A real world example - Facebook User Object

The next code block builds on the pattern examples and implements a Facebook user object.

''**************************************************************************
'' Copyright 2012 Larry Boeldt 
'' Class: facebook_user  V1.0    2012-01-26
'' Author: Larry Boeldt - lboeldt@scs-inc.net; larry@boeldt.net
''
'' Description:
''   Facebook user object
''
''**************************************************************************
class facebook_user
    dim m_id '' The user's Facebook ID
    dim m_name '' The user's full name
    dim m_first_name '' The user's first name
    dim m_middle_name '' The user's middle name
    dim m_last_name '' The user's last name
    dim m_gender '' The user's gender: female or male
    dim m_locale '' The user's locale
    dim m_languages '' The user's languages
    dim m_link '' The URL of the profile for the user on Facebook
    dim m_username '' The user's Facebook username
    dim m_third_party_id '' An anonymous, but unique identifier for the user;
                         '' only returned if specifically requested via the fields URL parameter
    dim m_timezone '' The user's timezone offset from UTC
    dim m_updated_time '' The last time the user's profile was updated;
                       '' changes to the languages, link, timezone, verified,
                       '' interested_in, favorite_athletes, favorite_teams,
                       '' and video_upload_limits are not not reflected in this value
    dim m_verified '' The user's account verification status, either true or false (see below)
    dim m_bio '' The user's biography
    dim m_birthday '' The user's birthday
    dim m_education '' A list of the user's education history
    dim m_email '' The proxied or contact email address granted by the user
    dim m_hometown '' The user's hometown
    dim m_interested_in '' The genders the user is interested in
    dim m_location '' The user's current city
    dim m_political '' The user's political view
    dim m_favorite_athletes '' The user's favorite athletes; this field
                            '' is deprecated and will be removed in the near future
    dim m_favorite_teams '' The user's favorite teams; this field
                '' is deprecated and will be removed in the near future
    dim m_quotes '' The user's favorite quotes
    dim m_relationship_status '' The user's relationship status: Single,
                  '' In a relationship, Engaged, Married, It's complicated,
                  '' In an open relationship, Widowed, Separated, Divorced,
                  '' In a civil union, In a domestic partnership
    dim m_religion '' The user's religion
    dim m_significant_other '' The user's significant other
    dim m_video_upload_limits '' The size of the video file and the length
              '' of the video that a user can upload; only returned
              '' if specifically requested via the fields URL parameter
    dim m_website '' The URL of the user's personal website
    dim m_token ''
    dim m_json_str ''
    dim m_graph_url ''
    dim fbu '' Facebook utility object
    
    sub Class_Initialize()
        m_id = ""
        m_name = ""
        m_first_name = ""
        m_middle_name = ""
        m_last_name = ""
        m_gender = ""
        m_locale = ""
        m_languages = ""
        m_link = ""
        m_username = ""
        m_third_party_id = ""
        m_timezone = ""
        m_updated_time = ""
        m_verified = ""
        m_bio = ""
        m_birthday = ""
        m_education = ""
        m_email = ""
        m_hometown = ""
        m_interested_in = ""
        m_location = ""
        m_political = ""
        m_quotes = ""
        m_relationship_status = ""
        m_religion = ""
        m_significant_other = ""
        m_video_upload_limits = ""
        m_website = ""
        
        set fbu = new fb_utility
    end sub

    public property get graph_url()
        graph_url = m_graph_url
    end property
    
    public property get json_string()
        json_string = m_json_str
    end property
    
    public property get token()
        token = m_token
    end property
    public property let token(value)
        m_token = value
    end property
    
    public property get id()
        id = m_id
    end property
    public property let id(value) 
        m_id = value 
    end property

    public property get name()
        name = m_name
    end property
    public property let name(value) 
        m_name = value 
    end property

    public property get first_name()
        first_name = m_first_name
    end property
    public property let first_name(value) 
        m_first_name = value 
    end property

    public property get middle_name()
        middle_name = m_middle_name
    end property
    public property let middle_name(value) 
        m_middle_name = value 
    end property

    public property get last_name()
        last_name = m_last_name
    end property
    public property let last_name(value) 
        m_last_name = value 
    end property

    public property get gender()
        gender = m_gender
    end property
    public property let gender(value) 
        m_gender = value 
    end property

    public property get locale()
        locale = m_locale
    end property
    public property let locale(value) 
        m_locale = value 
    end property

    public property get languages()
        languages = m_languages
    end property
    public property let languages(value) 
        m_languages = value 
    end property

    public property get link()
        link = m_link
    end property
    public property let link(value) 
        m_link = value 
    end property

    public property get username()
        username = m_username
    end property
    public property let username(value) 
        m_username = value 
    end property

    public property get third_party_id()
        third_party_id = m_third_party_id
    end property
    public property let third_party_id(value) 
        m_third_party_id = value 
    end property

    public property get timezone()
        timezone = m_timezone
    end property
    public property let timezone(value) 
        m_timezone = value 
    end property

    public property get updated_time()
        updated_time = m_updated_time
    end property
    public property let updated_time(value) 
        m_updated_time = value 
    end property

    public property get verified()
        verified = m_verified
    end property
    public property let verified(value) 
        m_verified = value 
    end property

    public property get bio()
        bio = m_bio
    end property
    public property let bio(value) 
        m_bio = value 
    end property

    public property get birthday()
        birthday = m_birthday
    end property
    public property let birthday(value) 
        m_birthday = value 
    end property

    public property get education()
        education = m_education
    end property
    public property let education(value) 
        m_education = value 
    end property

    public property get email()
        email = m_email
    end property
    public property let email(value) 
        m_email = value 
    end property

    public property get hometown()
        hometown = m_hometown
    end property
    public property let hometown(value) 
        m_hometown = value 
    end property

    public property get interested_in()
        interested_in = m_interested_in
    end property
    public property let interested_in(value) 
        m_interested_in = value 
    end property

    public property get location()
        location = m_location
    end property
    public property let location(value) 
        m_location = value 
    end property

    public property get political()
        political = m_political
    end property
    public property let political(value) 
        m_political = value 
    end property

    public property get quotes()
        quotes = m_quotes
    end property
    public property let quotes(value) 
        m_quotes = value 
    end property

    public property get relationship_status()
        relationship_status = m_relationship_status
    end property
    public property let relationship_status(value) 
        m_relationship_status = value 
    end property

    public property get religion()
        religion = m_religion
    end property
    public property let religion(value) 
        m_religion = value 
    end property

    public property get significant_other()
        significant_other = m_significant_other
    end property
    public property let significant_other(value) 
        m_significant_other = value 
    end property

    public property get video_upload_limits()
        video_upload_limits = m_video_upload_limits
    end property
    public property let video_upload_limits(value) 
        m_video_upload_limits = value 
    end property

    public property get website()
        website = m_website
    end property
    public property let website(value) 
        m_website = value 
    end property

    public sub LoadMe()
        dim strFields
        dim obj
        
        m_graph_url = "https://graph.facebook.com/me?access_token=" & _
            m_token 
        
        m_json_str = fbu.get_page_contents( m_graph_url )
        
        set obj = JSON.parse( m_json_str )
        
        load_from_json_user obj
        
    end sub

    public sub Load(ID)
        dim strFields
        dim obj
        
        m_graph_url = "https://graph.facebook.com/" & _
                      ID & "?access_token=" & _
                      m_token 
        
        m_json_str = fbu.get_page_contents( m_graph_url )
        
        set obj = JSON.parse( m_json_str )
        
        load_from_json_user obj
        
    end sub

    ''**************************************************************************
    '' Copyright 2012 Larry Boeldt 
    '' Function: load_from_json_user  V1.0    2012-01-26
    '' Author: Larry Boeldt - lboeldt@scs-inc.net; larry@boeldt.net
    '' Parameter(s):
    ''   fb_obj - The facebook object as returned from JSON.parse
    ''
    '' Description:
    ''   This function attempts to safely assign all user parameters from a 
    '' fasebook object so that you can consistently address the properties in 
    '' your code without concern about errors resulting from properties that
    '' are missing in the return json object
    ''**************************************************************************
    public sub load_from_json_user(fb_obj)
        on error resume next
        m_id = fb_obj.id
        m_name = fb_obj.name
        m_first_name = fb_obj.first_name
        m_middle_name = fb_obj.middle_name
        m_last_name = fb_obj.last_name
        m_gender = fb_obj.gender
        m_locale = fb_obj.locale
        m_languages = fb_obj.languages
        m_link = fb_obj.link
        m_username = fb_obj.username
        m_third_party_id = fb_obj.third_party_id
        m_timezone = fb_obj.timezone
        m_updated_time = fb_obj.updated_time
        m_verified = fb_obj.verified
        m_bio = fb_obj.bio
        m_birthday = fb_obj.birthday
        m_education = fb_obj.education
        m_email = fb_obj.email
        m_hometown = fb_obj.hometown.name
        m_interested_in = fb_obj.interested_in
        m_location = fb_obj.location.name
        m_political = fb_obj.political
        m_quotes = fb_obj.quotes
        m_relationship_status = fb_obj.relationship_status
        m_religion = fb_obj.religion
        m_significant_other = fb_obj.significant_other
        m_video_upload_limits = fb_obj.video_upload_limits
        m_website = fb_obj.website
        on error goto 0
        err.clear
    end sub
    
end class

Pulling them all together with the fb_graph_api object

To keep code that uses this library uncluttered, the fb_graph_api class implements a function that returns a ready made object.

What's in the current library?

I provided everything I'm working on as of this writing, however only some functions are ready for your consumption. The other examples are in alpha mode; use at your own risk. Here are the working objects and associated graph_api "shortcuts":

Graph API Methods

Presently only the post_to_wall method is implemented.

The test page for wall post is post_wall_test.asp. Presently you can only post to the currently logged-in user's wall.

The post to wall takes the following parameters:

Points of interest

The DTO classes can be stored in the session because they make use of only VBScript variants and there are no objects (like scripting.dictionary) that raise threading model issues.

Conclusion

While the example here does not support the full Graph API, I think you'll be able to wade through any other API data by referencing the examples here. If you implement another module, post it here and I'll be sure to included it in a new release. I'll release a new version every third month of the year for the next year. Your feedback, advice, and votes are always appreciated.

History

• Release version 1.