We Keep Coding

How to download the picture of a Google+ user only if it has changed after a certain date?

I am using Google API to get information about an authenticated user. I can get the basic profile information, such as the ID and the full name. From the profile information, I can get the URL to the picture:
var plusMeUri = new Uri($"https://www.googleapis.com/plus/v1/people/me?key=<APP-ID>&access_token=<ACCESS-TOKEN>");
string userResponse = await HttpClient.GetStringAsync(plusMeUri);
JObject userObject = JObject.Parse(userResponse);
...
var imageObject = userObject.GetValue("image") as JObject;
var pictureUrl = imageObject.GetValue("url").Value<string>();
var pictureUri = new Uri(pictureUrl);
string uri = $"{pictureUri.Scheme}://{pictureUri.Host}{pictureUri.AbsolutePath}";
var pictureRequest = new HttpRequestMessage(HttpMethod.Get, uri);
pictureRequest.Headers.IfModifiedSince = <previous-timestamp>;
HttpResponseMessage pictureResponse = await HttpClient.SendAsync(pictureRequest);
if (pictureResponse.StatusCode == HttpStatusCode.NotModified)
// No need to handle anything else
return;
Question
I do not want to download the user's picture if it has not changed. This is why I am using the IfModifiedSince property. It does work with Facebook's API but it does not seem to work with Google's. How can I make it work?

From the information given, it seems like what you're trying to do is determine whether the image you're downloading/about to download is the same image as you've downloaded before. After looking at the Google+ API docs, it looks like the header you've been using isn't officially (at least not obviously) supported by their APIs.
But this is not the only way we can determine whether the image has changed or not (in fact, date last modified isn't necessarily the best way to do this anyway). Alternative methods include:
1) diffing the two images
2) checking the url (if we can assume different resources have different urls)
1 is likely the most accurate but also likely the least efficient, so I'll leave that to you to solve if you decide to go that route. I think the most promising is #2. I went ahead and played around with the API a little bit and it looks like the image.url field changes when you update your profile picture.
For example, here are my last two Google+ profile picture URLs:
https://lh4.googleusercontent.com/-oaUVPGFNkV8/AAAAAAAAAAI/AAAAAAAAAqs/KM7H8ZIFuxk/photo.jpg?sz=50
https://lh4.googleusercontent.com/-oaUVPGFNkV8/AAAAAAAAAAI/AAAAAAAAl24/yHU99opjgN4/photo.jpg?sz=50
As such, instead of waiting for the response from the server and checking its header to decide whether the image has been updated or not, you may be able to short-circuit the entire HTTP request by simply checking whether the last image you pulled down was from the same url or not. If it was from the same URL, it's likely you've already acquired that image otherwise you may not have it so should incur the cost of downloading anyway.
In this case, your code would read something like:
var imageObject = userObject.GetValue("image") as JObject;
var pictureUrl = imageObject.GetValue("url").Value<string>();
if(pictureUrl != <previous-picture-url>)
{
// insert get new picture logic here...
}

Skybrud social Log in via Facebook?

I'm usinng skybrud social to allow users to log into my site via Facebook, but am having a problem.
For some reason, the response never contains anything other than the Name and Id of the user... everything else is null.
var url = client.GetAuthorizationUrl(state, "public_profile", "email");
var service = FacebookService.CreateFromAccessToken(userAccessToken);
FacebookMeResponse user = service.Methods.Me();
Has anyone experienced this before? What could be the problem?

Facebook has multiple versions of their Graph API. In the most recent version (2.4), less fields are returned by default, and you instead have to tell the API to return the fields that you need. What version of the API you're using depends on the time you registered your app with Facebook.
Based on your code, it seems that you're using an older version of Skybrud.Social. If you update to the most recent version (0.9.4.1), you can do something like this:
// Declare the options for the call to the API
FacebookGetUserOptions options = new FacebookGetUserOptions("me") {
Fields = "name,email,gender"
};
// Make the call to the API
FacebookUserResponse response = service.Users.GetUser(options);
Hope this answers your questions ;)

Facebook Graph API {id}/feed?limit=x - restrict to messages since a certain message id

I have a small problem, I am working on an aggregation application that is collecting messages from pages in realtime.
This is working fine, but I get the same message on every call and then filter out the messages that I have already seen manually.
This means that a large amount of data is being transferred every time I make a call to the graph api.
Is there a way to limit the message as messages since this message id?
currently using the c# Facebook SDK
var fb = new FacebookClient("access_token");
dynamic parameters = new ExpandoObject();
parameters.limit = _facebookMessagesToRetrieveAtATime.ToString(CultureInfo.InvariantCulture);
//Want to add a new param here to say messages since this id.
var facebookUrl = String.Format("{0}/feed", "Page ID");
dynamic resp = fb.Get(facebookUrl, parameters);
Thanks in advance.

You can use the since url parameter in your calls, as described at https://developers.facebook.com/docs/graph-api/using-graph-api/v2.1#paging
This would make it necessary that you store somewhere in your application the timestamp when you last requested the respective feed
This would yield in
var facebookUrl = String.Format("{0}/feed?since={last_update_timestamp}", "Page ID");
where {last_update_timestamp} is the timestamp (unixtime in seconds) of the last update.

Facebook C# SDK - Post to wall

I'm developing an asp.net MVC 3 Facebook app and I am trying to post a message to my wall. Here is my code:
FacebookWebClient client = new FacebookWebClient();
// Post to user's wall
var postparameters = new Dictionary<string, object>();
postparameters["message"] = "Hello world!";
postparameters["name"] = "This is a name";
postparameters["link"] = "http://thisisalink.com;
postparameters["description"] = "This is a description";
var result = client.Post("/me/feed", postparameters);
I can get the access token using client.AccessToken, so I'm assuming I don't have to set it anywhere. This code produces no errors and for the result I get an ID. However, when I bring up my Facebook, I see nothing on my wall nor in my news feed. I'm not sure what I'm missing. I've looked at related questions here at StackOverflow, but I see no reports/questions similar to mine. I've also tried changing the code based on what I've seen in other posts, but to no avail. I also checked my Facebook account settings and I see my application listed with permission to post to my wall. I also tried posting a message to my wall via the Graph API explorer and I'm getting the same result. I get an ID in return, but when I check my Facebook account I see nothing. At been at this for a couple of days. Any help would be greatly appreciated.
Thanks in advance.
[EDIT]
I wonder if something is wrong with my app generated access_token. Using this access_token, as I mentioned in my post, I get the same result using the Graph API explorer. An ID is returned, but no message on my wall. However, if I give the Graph API explorer permission to post to my wall and use its own generated access_token, I can successfully post a message using the explorer. Here's the FB login button code:
<div>
<h1>Login using Facebook</h1>
<p><fb:login-button perms="user_location, publish_stream, email"></fb:login-button></p>
</div>

Basically you need to add an additional parameter into your post parameters.
args["access_token"] = account.access_token;
this is the token of the specific page.
I wont repeat the code, follow here for example: Post On Facebook Page As Page Not As Admin User Using Facebook C# SDK
(second answer)

Did you request right App permissions to Facebook in your action method?
Try: [CanvasAuthorize(Permissions = "user_location, publish_stream, email")]

Did you append the access_token to the URL? See example here. It's also documented here (see Using the Access Token).
/me/feed?access_token=<access_token>

with one small change, your code works fine for me. you have to pass the users auth token into the constructor like this...
var client = new FacebookClient(accessToken);
// Post to user's wall
var postparameters = new Dictionary<string, object>();
postparameters["message"] = "Hello world!";
postparameters["name"] = "This is a name";
postparameters["link"] = "http://thisisalink.com;
postparameters["description"] = "This is a description";
var result = client.Post("/me/feed", postparameters);
this method works for me, although i am not sure which facebook sdk you are using.
i'm using http://facebooksdk.net/ its quite good so if you're not using it i would recommend it

Grabbing Cookies in Web Browser Control - WP7

In order to log into a certain part of a website the users of my application require their cookie. To do this I need to grab it and pass it to url.
Does anyone know how to grab a certain websites cookie from the browser control?
I saw this method but wasn't quite clear.
Thanks, TP.

As of WP 7.1 Mango "release", if one may call it, please see the WebBrowser Control Overview for Windows Phone. It has been recently updated a little bit, and it turns out that they actually have added some support for cookie-retrieval from the WebBrowser. On the bottom of the page you will find a tiny link GetCookies(WebBrowser) pointing to description of a new class: WebBrowserExtensions with this very handy method. Yes, this class has only that one single member. It's an extension method, I suppose no explanations needed on that.
I have not played with this method much, but it seems that this will allow you to access the very same thing as the JS trick: the cookieset for the current URL. It probably will not allow to set anything, nor to peek cookies for other URLs. Maybe if you play hard with the CookieContainer you will receive, but I doubt.
On the 7.0 release, I've been struggling quite hard to achieve "cookie transparency" for my App. Long story short, my app was doing some background HTTP requests, and also had a WebBrowser to show some online content -- and "it would be great" if both sources of connections would emit the same cookies to the server.. And guess what, my application had to make the first request, then let the browser navigate. With such requirements, there was virtually is no way to achieve consistency of the cookies - bah, even with the current new and glorious GetCookie method, I suppose it would be damn hard. So, to the point - it was possible, but needed to use some hidden API, that is present publicitly on the Phone, but is hidden in the SDK. The API is available the (public) class System.Net.Browser.WebRequestCreator, freely available. The quirk is: in the SDK this class has a single public static property "IWebRequestCreate ClientHttp" with a method "Create" that you can use to "factory" your "raw http" connections - in case you dont want to use the WebClient for some reason. On the phone, and on the emulator, there is a second public static property called "IWebRequestCreate BrowserHttp", easily returned by Reflection:
PropertyInfo brwhttp = typeof(System.Net.Browser.WebRequestCreator)
.GetProperty("BrowserHttp")
with this property, you will be able to obtain a "special" internal instance of IWebRequestCreate that is used internally by the WebBrowser. By opening your background HTTP requests with this class, you will get your cookies automatically set as if they were created/sent by the WebBrowser control, but in turn - you will NOT be able to modify http headers, userprovide http user authentication and neither do a few lowlevel things - because all that settings will be synced with the WebBrowser's data stored for current 'system user instance', if I'm allowed to call it as such on the single-user Phone device heh. The interoperation between connections and the WebBrowser works both ways - if your HTTP connection (created with use of the 'hidden property') receives any settings/cookies/etc -- then the WebBrowser will instantly notice them and update its own cache. No cookie/session loss on neither of the sides!
If you need to passively get cookies for your subsequent connections after some first WebBrowser navigation - please use the GetCookie or the JS way.
But if you need your code to be first, and then pass authz to the WebBrowser -- you will probably have to dig deeper and use the above.. It's been hidden, so please resort to the other means first!
..and don't ask me how did I found it or how much time it took :P
have a nice fun with it
//edit: I've just found out, that the BrowserHttp property is a normal Silverlight's way to access the Browser's connection factory, please see BrowserHttp. It seems that it is only has been hidden in the 'miniSilverlight' written for the WP7 platform!

The approach being described in the post you linked is to use the WebBrowser control's InvokeScript method to run some javascript. However the post appears to use a "cookies" collection which doesn't actually exist.
string cookie = myWebBrowser.InvokeScript("document.cookie") as string;
Now for the hard part the string you get contains all pertinent cookie name/value pairs for the page with the values still being Url encoded. You will need to parse the returned string for the value you need.
See document.cookie property documentation.
Edit:
Looking at it fresh instead of relying on the post, InvokeScript invokes named function on the window of the host browser. Hence the page being displayed in the WebBrowser would itself need to include a function like:-
function getCookie() { return document.cookie; }
Then the InvokeScript would look like:-
string cookie = myWebBrowser.InvokeScript("getCookie");

As #quetzalcoatl already suggested, you can use internal instance of WebRequestCreator to share cookies between browser instances and instances of WebRequest. You don't get to access the cookies directly though, I think that's just a security measure by Microsoft.
This code below creates a WebReqeust object, connected to CookieContainer of WebBrowser instance. It then posts to a url to log in the user and store cookies in the container.
After it's done, all browser instances within the app instance will have required set of cookies.
var browser = new WebBrowser();
var brwhttp = typeof (WebRequestCreator).GetProperty("BrowserHttp");
var requestFactory = brwhttp.GetValue(browser, null) as IWebRequestCreate;
var uri = new Uri("https://www.login.com/login-handler");
var req = requestFactory.Create(uri);
req.Method = "POST";
var postParams = new Dictionary<string, string> {
{"username", "turtlepower"},
{"password": "ZoMgPaSSw0Rd1"}
};
req.BeginGetRequestStream(aReq => {
var webRequest = (HttpWebRequest)aReq.AsyncState;
using (var postStream = webRequest.EndGetRequestStream(aReq)) {
// Build your POST request here
var postDataBuilder = new StringBuilder();
foreach (var pair in paramsDict) {
if (postDataBuilder.Length != 0) {
postDataBuilder.Append("&");
}
postDataBuilder.AppendFormat("{0}={1}", pair.Key, HttpUtility.UrlEncode(pair.Value));
}
var bytes = Encoding.UTF8.GetBytes(postDataBuilder.ToString());
postStream.Write(bytes, 0, bytes.Length);
}
// Receive response
webRequest.BeginGetResponse(aResp => {
var webRequest2 = (HttpWebRequest) aResp.AsyncState;
webRequest = (HttpWebRequest)aResp.AsyncState;
string resp;
using (var response = (HttpWebResponse)webRequest2.EndGetResponse(aResp)) {
using (var streamResponse = response.GetResponseStream()) {
using (var streamReader = new System.IO.StreamReader(streamResponse)) {
resp = streamReader.ReadToEnd();
}
}
}
}, webRequest);
}, req);
One of the issues I couldn't solve though was exceptions thrown when server returns 302 - it seems to throw WebException error with "Not found" description.

// Ensure this is set to true BEFORE navigating to the page
webBrowser1.IsScriptEnabled = true;
// Once the page has loaded, you can read the cookie string
string cookieString = webBrowser1.InvokeScript("eval", new string[] { "document.cookie;" }) as string;
The cookieString variable will contain the full cookie for the document. You can then parse the string.

There is an WebBrowser Extension class which is exactly developed for this:
CookieCollection tempCookies = Microsoft.Phone.Controls.WebBrowserExtensions.GetCookies(this.BrowserControl);