Rust
Outlook -- Get Number of Emails

Gets the number of emails in an Outlook folder. This uses the OData $count system query option. See OData System Query Option $count for general information.
This example first gets the combined total number of messages across all folders.
Note: This example requires Chilkat v9.5.0.68 or greater.
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let mut success = false;

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

let http = chilkat::Http::new();

// Use your previously obtained access token here:
// See the following examples for getting an access token:
//    Get Microsoft Graph OAuth2 Access Token (Azure AD v2.0 Endpoint).
//    Get Microsoft Graph OAuth2 Access Token (Azure AD Endpoint).
//    Refresh Access Token (Azure AD v2.0 Endpoint).
//    Refresh Access Token (Azure AD Endpoint).

http.set_auth_token("MICROSOFT_GRAPH_ACCESS_TOKEN");

let sb_response = chilkat::StringBuilder::new();

// This gets the combined total number of emails in all folders.
success = http.quick_get_sb("https://graph.microsoft.com/v1.0/me/messages/$count", &sb_response).is_ok();
if (!success) && (http.last_status() == 0) {
    println!("{}", http.last_error_text());
    return;
}

let json = chilkat::JsonObject::new();
json.set_emit_compact(false);

// If the status code was not 200, then it failed and the response is likely JSON:
if http.last_status() != 200 {
    println!("Status code = {}", http.last_status());
    let _ = json.load_sb(&sb_response);
    println!("{}", json.emit().unwrap_or_default());
    println!("Failed.");
    return;
}

// A success response payload contains just the integer value (it is not JSON)
println!("Combined Total Number of Emails = {}", sb_response.get_as_string().unwrap_or_default());
println!("--");

// ---------------------------------------------------------------------------
// To get the number of emails in a particular folder, we need to use the folder id.
// 

// In this example, we'd like to get number of messages in the folder "/Inbox/abc",
// but we must specify the corresponding folder_id.  The best way to do this is to create
// a local map of folderPaths-to-folderIds.
// We'll use the map created by this example:  Create Outlook Folder Map)
let ht_folder_map = chilkat::Hashtable::new();
let sb_map = chilkat::StringBuilder::new();
let _ = sb_map.load_file("qa_data/outlook/folderMap.xml", "utf-8");
let _ = ht_folder_map.add_from_xml_sb(&sb_map);

// Get the ID for the "/Inbox/abc" folder:
let Ok(folder_id) = ht_folder_map.lookup_str("/Inbox/abc") else {
    println!("Folder ID not found");
    return;
};

let _ = http.set_url_var("folder_id", &folder_id);

// Send the request get the folder information.
// In this case we are NOT using the $count system query option.
success = http.quick_get_sb("https://graph.microsoft.com/v1.0/me/mailFolders/{$folder_id}", &sb_response).is_ok();
if (!success) && (http.last_status() == 0) {
    println!("{}", http.last_error_text());
    return;
}

let _ = json.load_sb(&sb_response);
println!("{}", json.emit().unwrap_or_default());
println!("--");

if http.last_status() != 200 {
    println!("Status code = {}", http.last_status());
    println!("Failed.");
    return;
}

// The successful JSON response looks like this;

// 	{
// 	  "@odata.context": "https://graph.microsoft.com/v1.0/$metadata#users('me')/mailFolders/$entity",
// 	  "id": "AQMkADAwATM0MDAAMS1iNTcwLWI2NTEtMDACLTAwCgAuAAADsVyfxjDU406Ic4X7ill8xAEA5_vF7TKKdE6bGCRqXyl2PQAAAL8huv8AAAA=",
// 	  "displayName": "abc",
// 	  "parentFolderId": "AQMkADAwATM0MDAAMS1iNTcwLWI2NTEtMDACLTAwCgAuAAADsVyfxjDU406Ic4X7ill8xAEA5_vF7TKKdE6bGCRqXyl2PQAAAgEMAAAA",
// 	  "childFolderCount": 2,
// 	  "unreadItemCount": 0,
// 	  "totalItemCount": 3
// 	}
// 

// Get the integer value from the JSON like this:
let total_item_count = json.int_of("totalItemCount");
println!("totalItemCount = {}", total_item_count);

let child_folder_count = json.int_of("childFolderCount");
println!("childFolderCount = {}", child_folder_count);

// etc..