(.NET Core C#) Download File from Dropbox (Streaming)

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Downloads a file from Dropbox, streaming it directly to a file in the filesystem.

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

// A Dropbox access token should have been previously obtained.
// Dropbox access tokens do not expire.
// See Dropbox Access Token.

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

// Connect to Dropbox
bool success = rest.Connect("content.dropboxapi.com",443,true,true);
if (success != true) {
    Debug.WriteLine(rest.LastErrorText);
    return;
}

// Add request headers.
rest.AddHeader("Authorization","Bearer DROPBOX_ACCESS_TOKEN");

// The download "parameters" are contained in JSON passed in an HTTP request header.
// This is the JSON indicating the file to be downloaded:
// { 
//    "path": "/Homework/lit/hamlet.xml",
// }

Chilkat.JsonObject json = new Chilkat.JsonObject();
json.AppendString("path","/Homework/lit/hamlet.xml");
rest.AddHeader("Dropbox-API-Arg",json.Emit());

// Setup a file stream for the download
Chilkat.Stream fileStream = new Chilkat.Stream();
fileStream.SinkFile = "qa_output/hamletFromDropbox.xml";

// Indicate that the call to FullRequestNoBody should send the response body
// to fileStream if the response status code is 200.
// If a non-success response status code is received, then nothing
// is streamed to the output file and the error response is returned by FullRequestNoBody.
int expectedStatus = 200;
rest.SetResponseBodyStream(expectedStatus,true,fileStream);

string responseStr = rest.FullRequestNoBody("POST","/2/files/download");
if (rest.LastMethodSuccess != true) {
    Debug.WriteLine(rest.LastErrorText);
    return;
}

// When successful, Dropbox responds with a 200 response code.
if (rest.ResponseStatusCode != 200) {
    // Examine the request/response to see what happened.
    Debug.WriteLine("response status code = " + Convert.ToString(rest.ResponseStatusCode));
    Debug.WriteLine("response status text = " + rest.ResponseStatusText);
    Debug.WriteLine("response header: " + rest.ResponseHeader);
    Debug.WriteLine("response body (if any): " + responseStr);
    Debug.WriteLine("---");
    Debug.WriteLine("LastRequestStartLine: " + rest.LastRequestStartLine);
    Debug.WriteLine("LastRequestHeader: " + rest.LastRequestHeader);
    return;
}

// Information about the downloaded file is also available as JSON in a response header.
// The "dropbox-api-result" response header contains the information.  For example:
string apiResult = rest.ResponseHdrByName("dropbox-api-result");
Debug.WriteLine(apiResult);

// In this case, the pretty-formatted dropbox-api-result JSON looks like this:
// { 
//   "name": "hamlet.xml",
//   "path_lower": "/homework/lit/hamlet.xml",
//   "path_display": "/Homework/lit/hamlet.xml",
//   "id": "id:74FkdeNuyKAAAAAAAAAAAQ",
//   "client_modified": "2016-06-02T23:19:00Z",
//   "server_modified": "2016-06-02T23:19:00Z",
//   "rev": "9482db15f",
//   "size": 279658
// }

// Load the JSON, pretty-print it, and demonstrate how to get some values...
Chilkat.JsonObject jsonResult = new Chilkat.JsonObject();
jsonResult.EmitCompact = false;
jsonResult.Load(apiResult);
// Show the JSON pretty-printed...
Debug.WriteLine(jsonResult.Emit());

// Sample code to get data from the JSON response:
int size = jsonResult.IntOf("size");
Debug.WriteLine("size = " + Convert.ToString(size));

string rev = jsonResult.StringOf("rev");
Debug.WriteLine("rev = " + rev);

string clientModified = jsonResult.StringOf("client_modified");
Chilkat.CkDateTime ckdt = new Chilkat.CkDateTime();
ckdt.SetFromTimestamp(clientModified);
bool bLocalTime = true;
Chilkat.DtObj dt = ckdt.GetDtObj(bLocalTime);
Debug.WriteLine(Convert.ToString(dt.Day) + "/" + Convert.ToString(dt.Month) + "/" + Convert.ToString(dt.Year) + " " + Convert.ToString(dt.Hour)
     + ":" + Convert.ToString(dt.Minute));