(C# UWP/WinRT) Download Photo to a File

Assuming we have the ID of a Photo, this example demonstrates how to download the photo image data to a file.

Chilkat Universal Windows Platform (UWP) / WinRT Downloads Chilkat for the Universal Windows Platform (UWP)

// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

// This example assumes a previously obtained an access token
Chilkat.OAuth2 oauth2 = new Chilkat.OAuth2();
oauth2.AccessToken = "FACEBOOK-ACCESS-TOKEN";

Chilkat.Rest rest = new Chilkat.Rest();

// Connect to Facebook...
bool success = await rest.ConnectAsync("graph.facebook.com",443,true,true);
if (success != true) {
    Debug.WriteLine(rest.LastErrorText);
    return;
}

// Provide the authentication credentials (i.e. the access key)
rest.SetAuthOAuth2(oauth2);

// Assumes we've already obtained a Photo ID.
string photoId = "10210199026347451";

Chilkat.StringBuilder sbPath = new Chilkat.StringBuilder();
sbPath.Append("/v2.7/");
sbPath.Append(photoId);

// First we're going to get the photo informaton so we can get the URL of the image file data.
// Select the fields we want.
// See https://developers.facebook.com/docs/graph-api/reference/photo/
rest.AddQueryParam("fields","id,album,images");

string responseJson = await rest.FullRequestNoBodyAsync("GET",sbPath.GetAsString());
if (rest.LastMethodSuccess != true) {
    Debug.WriteLine(rest.LastErrorText);
    return;
}

Chilkat.JsonObject json = new Chilkat.JsonObject();
json.EmitCompact = false;
json.Load(responseJson);

// Show the JSON in human-readable format.
Debug.WriteLine(json.Emit());

// Get the image URL.
string imageUrl = json.StringOf("images[0].source");
Debug.WriteLine("Downloading from " + imageUrl);

Chilkat.StringBuilder sbImageUrl = new Chilkat.StringBuilder();
sbImageUrl.Append(imageUrl);

// Build the output local file path.
Chilkat.StringBuilder sbToPath = new Chilkat.StringBuilder();
sbToPath.Append("qa_output/fb");
sbToPath.Append(json.StringOf("id"));
bool bCaseSensitive = false;
if (sbImageUrl.Contains(".jpg",bCaseSensitive) == true) {
    sbToPath.Append(".jpg");
}
else {
    sbToPath.Append(".png");
}

Debug.WriteLine("Downloading to " + sbToPath.GetAsString());

// Download using Chilkat HTTP.
Chilkat.Http http = new Chilkat.Http();
success = await http.DownloadAsync(imageUrl,sbToPath.GetAsString());
if (success != true) {
    Debug.WriteLine(http.LastErrorText);
}
else {
    Debug.WriteLine("Downloaded.");
}