Parsing XML file from the REST API

Question

Please suggest how I can improve my code (like memory leakage, which pattern to use etc.). I have to parse a book XML in two ways: first from an FTP file and second from the REST API. I implemented the methods in one class.

public void GetBooksFromApi(int bookId, int bookNumber = 0)
 {
 string ApiBookIDPrefix = ConfigurationManager.AppSettings["ApiBookIDPrefix"].ToString();
 string key = ConfigurationManager.AppSettings["BookApiKey"].ToString();
 string apiBookIdValue = $"{ApiBookIDPrefix}{bookId}";
 string restApiBookUrl = $"{ApiDownloadUrl}?BookID={apiBookIdValue}&key={key}&bookNumber={bookNumber}&limit=1";
 string bookName = String.Empty;
 string clientFolderPath = String.Empty;
 string bookContent = String.Empty;
 try
 {//here to get response, parse xml and creating files process
 using (Stream xmlResponseStream = GetRestApiResponse(restApiBookUrl))
 {
 IEnumerable<XElement> xmlRecords = ParseBookXml(xmlResponseStream);
 if (xmlRecords == null)
 throw new NullReferenceException($"No Book found to parse from rest api xml");
 foreach (var xmlRecord in xmlRecords)
 {
 if (xmlRecord.Element("BookError") == null)
 {
 bookName = GetBookName(xmlRecord, bookId);
 clientFolderPath = $@"{BaseFolder}\{bookId}";
 bookContent = xmlRecord.ToString();
 if (!string.IsNullOrEmpty(bookContent))
 CreateFile(clientFolderPath, bookName, bookContent);
 }
 }
 }
 }
 catch (Exception ex)
 {
 log.Error($"Unable to retrieve Book for {bookId.ToString()} with URL", ex);
 throw ex;
 }
 }
 public IEnumerable<XElement> ParseBookXml(Stream response)
 {
 IEnumerable<XElement> bookRecords = null;
 try
 {
 XDocument bookDoc = new XDocument();
 bookDoc = XDocument.Load(response);
 bookRecords = bookDoc.Root.Elements("bookReport").ToList();
 return bookRecords;
 }
 catch (Exception ex)
 {
 log.Error($"Unable to load XML response from Rest Api Url .", ex);
 return bookRecords;
 }
 }
 public string GetBookName(XElement bookXmlRecord, int bookId)
 {
 string bookName = string.Empty;
 string bookNumberString = String.Empty;
 string bookNumberVal = bookXmlRecord.Element("bookNumber")?.Value;
 DateTime bookDateVal = now(); // today date
 bool validBookDate = DateTime.TryParse(bookXmlRecord.Element("BookDate")?.Value, out bookDateVal);
 if (!validBookDate)
 throw new InvalidCastException($"Unable to parse Book Date from rest api xml");
 bookNumberString = GetBookNumberString(int.Parse(bookNumberVal));
 bookName = $"Book-{bookId.ToString().PadLeft(4, '0')}-{reportDate:yyyyMMdd}{bookNumberString}.xml";
 return bookName;
 }
 public bool CreateFile(string clientFolder, string fileName, string xmlResponse)
 {
 try
 {
 string filePath = $@"{clientFolder}\{fileName}";
 if (!Directory.Exists(clientFolder))
 Directory.CreateDirectory(clientFolder);
 File.WriteAllText(filePath, xmlResponse);
 return true;
 }
 catch (Exception ex)
 {
 log.Error($"Unable to create book in path {clientFolder}.", ex);
 return false;
 }
 }

Answer 1

How to improve your code:

1. Rather than using the XML document and XML elements, use a concrete class for books and their collection.
2. With the help of the book class you can now to de-serialize the response of API.
3. In addition to that, add GetBookName() and other relevant behavior to the book's class

I believe your response XML will look as follows:

<bookReport>
 <book>
 <bookId>12345</bookId>
 <bookNumber>12345</bookNumber>
 <bookDate>02/11/2021</bookDate>
 </book>
 <book>
 <bookId>12345</bookId>
 <bookNumber>12345</bookNumber>
 <bookDate>02/11/2021</bookDate>
 </book>
 <book>
 <bookId>12345</bookId>
 <bookNumber>12345</bookNumber>
 <bookDate>02/11/2021</bookDate>
 </book>
</bookReport>

Declare classes for de-serializing as follows:

public class Book
{
 public int BookId { get; set; }
 public int BookNumber { get; set; } 
 public DateTime reportDate { get; set; }
 
 // additional behavior or calculated fields here
 public string GetBookName {
 return $"Book-{BookId.PadLeft(4, '0')}-{reportDate.ToShortDateString()}{BookNumber}.xml"; 
 }
}
[XmlRoot("bookReport")] // to set a predefined xml root name
public class bookReport : List<Book>
{
 public bookReport()
 {
 
 }
}