(.NET Core C#) Xero Download Attachment for an Item (such as an Invoice)

Demonstrates how to download a particular attachment for a particular Xero item.

For more information, see https://developer.xero.com/documentation/api/attachments#GET

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

Chilkat.Http http = new Chilkat.Http();

Chilkat.JsonObject jsonToken = new Chilkat.JsonObject();
bool success = jsonToken.LoadFile("qa_data/tokens/xero-access-token.json");
if (success == false) {
    Debug.WriteLine(jsonToken.LastErrorText);
    return;
}

http.AuthToken = jsonToken.StringOf("access_token");

// Replace the value here with an actual tenant ID obtained from this example:
// Get Xero Tenant IDs
http.SetRequestHeader("Xero-tenant-id","83299b9e-5747-4a14-a18a-a6c94f824eb7");

http.Accept = "application/json";

// The example to list Xero attachments shows how to get attachment information.
// Here's a sample JSON response obtained form listing attachments:
// Your application can get the AttachmentID's and filenames from it.

// {
//   "Id": "24bfbcb9-dec9-4d33-835c-8f165d776766",
//   "Status": "OK",
//   "ProviderName": "Chilkat2222",
//   "DateTimeUTC": "\/Date(1587213296972)\/",
//   "Attachments": [
//     {
//       "AttachmentID": "daf106e2-8634-4349-bfcc-86c1df0793b2",
//       "FileName": "penguins.jpg",
//       "Url": "https://api.xero.com/api.xro/2.0/Invoices/0032f627-3156-4d30-9b1c-4d3b994dc921/Attachments/penguins.jpg",
//       "MimeType": "image/jpg",
//       "ContentLength": 777835
//     }
//   ]
// }

string url = "https://api.xero.com/api.xro/2.0/{$Endpoint}/{$Guid}/Attachments/{$AttachmentId}";

// Endpoint can be Invoices, Receipts, CreditNotes, PurchaseOrders, etc.
http.SetUrlVar("Endpoint","Invoices");

// Guid is the ID of the item, such as the InvoiceID.
http.SetUrlVar("Guid","0032f627-3156-4d30-9b1c-4d3b994dc921");

// AttachmentId is the ID of the particular attachment to be downloaded
http.SetUrlVar("AttachmentId","daf106e2-8634-4349-bfcc-86c1df0793b2");

// Download the attachment data into bd.
Chilkat.BinData bd = new Chilkat.BinData();
success = http.QuickGetBd(url,bd);
if (success == false) {
    Debug.WriteLine(http.LastErrorText);
    return;
}

Debug.WriteLine("Response Status Code: " + Convert.ToString(http.LastStatus));

if (http.LastStatus == 200) {
    // Success
    // Save to a file..
    success = bd.WriteFile("qa_output/penguines.jpg");
}
else {
    // Failed.  bd contains error information..
    Debug.WriteLine(bd.GetString("utf-8"));
}