how to call Call Async Methods in Parallel.ForEach loop properly

Question

how to call Call Async Methods in Parallel.ForEach loop properly.billDataService.SaveBillDetail and GetProfileDetails both are async methods.data saving in MongoDB in SaveBillDetail .

public async Task ConvertXMLFileToJSON()
        {
            try
            {

                if (Directory.Exists(_appSettings.DocumentsStorage))
                {
                    int i = 1; //Test
                    bool exists = Directory.GetFiles(_appSettings.DocumentsStorage).Any(x => x.Equals(Path.Combine(_appSettings.DocumentsStorage, "Ready.txt"), StringComparison.OrdinalIgnoreCase)); //Need to check
                    if (exists)
                    {
                      Parallel.ForEach(System.IO.Directory.GetFiles(_appSettings.DocumentsStorage, "*.xml"), (currentFile) =>
                        {
                            try
                            {
                                XElement root = XElement.Load(currentFile); // or .Parse(string);
                                //Removing CDATA property from XElement.
                                XElement items = XElement.Parse(root.ToString().Replace("<![CDATA", "").Replace("]]>", "").Replace("[", ""));
                                //Removing XML_INFO Tag from XElement.
                                items.Elements("XML_INFO").Remove();
                                XmlDocument xmlDoc = new XmlDocument();
                                using (XmlReader xmlReader = items.CreateReader())
                                {
                                    xmlDoc.Load(xmlReader);
                                }

                                var json = JsonConvert.SerializeXmlNode(xmlDoc);
                                billDetails obj = JsonConvert.DeserializeObject<billDetails>(json);
                                BillDetails billDetails = new BillDetails();
                                billDetails.AccountNumber = obj.BILL_INFO.BILL_RUN.ACCT_INFO.ACCT_CODE;
                                billDetails.MobileNumber = obj.BILL_INFO.BILL_RUN.ACCT_INFO.PRINCIPAL_NO.STR_PRINCIPAL_NO;
                                billDetails.BillDate = DateTime.ParseExact(obj.BILL_INFO.BILL_RUN.BILL_PROP.TO_DATE, "dd/MM/yyyy", CultureInfo.InvariantCulture);
                                billDetails.DueAmount = obj.BILL_INFO.BILL_RUN.ACCT_INFO.ACCT_BALANCE_TRACE.TOTAL_DUE;
                                billDetails.CustomerName = obj.BILL_INFO.BILL_RUN.CUST_INFO.CUST_NAME.FULL_NAME;
                                billDetails.InvoiceId = obj.BILL_INFO.BILL_RUN.BILL_PROP.INVOICE_ID;
                                billDetails.DueDate = DateTime.ParseExact(obj.BILL_INFO.BILL_RUN.BILL_PROP.DUE_DATE, "yyyyMMdd hh:mm:ss", CultureInfo.InvariantCulture);
                                billDetails.RepositoryName = "postpaid";
                                billDetails.BillRun = obj.BILL_INFO.BILL_RUN; //tempObj2.BILL_INFO.ToString().Remove(0, 1);
                                billDetails.ObjectId = Guid.NewGuid().ToString();
                                if (billDetails != null)
                                {
                                    BillDataService billDataService = new BillDataService(_dbConfig);
                                    Console.WriteLine("SaveBillDetail");
                                    if (billDataService.SaveBillDetail(billDetails) != null)
                                    {
                                        Console.WriteLine("SaveBillDetail done");
                                        GetProfileDetails(billDetails);
                                        _logger?.LogInformation(i++ + "  File Success");
                                        Console.WriteLine(i++ + "  File Success");
                                        // File.Delete(file);  //Delete File 
                                    }
                                }

                            }
                            catch (Exception ex)
                            {
                                _logger?.LogError(ex, "Error");
                            }
                            finally { }
                        });
                    }
                }
            }

            catch (Exception ex)
            {
                _logger?.LogError(ex, "Error");
            }
            finally
            {

            }
        }


public async Task GetProfileDetails(BillDetails billDetails)
        {
            try
            {
                ProfileService profileService = new ProfileService(_dbConfig);
                var searchFilter = new SearchFilter
                {
                    Filters = new List<Filter>()
                };

                if (!string.IsNullOrEmpty(billDetails.AccountNumber))
                {
                    searchFilter.Filters.Add(new Filter() { PropertyName = "AccountNumber", Operator = Operator.Equals, Value = billDetails.AccountNumber, CaseSensitive = true });
                }

                if (searchFilter != null)
                {
                    Profile profile = await profileService.GetProfiles(searchFilter);
                    if (profile != null)
                    {
                        await SendMailNotification(profile, billDetails);
                    }
                    else
                    {
                        _logger?.LogError("Profile Info not found");

                    }
                }
            }
            catch (Exception ex)
            {
                _logger?.LogError(ex, "Error");
                throw;
            }
            finally { }
        }

normal for each loop I can able to call and save data in MongoDB.but Parallel.ForEach loop I cannot able to call the async method using await and data saving in mongo also not working.inside Parallel.ForEach loop I avoided using await of the front of the calling method.

Answer 1

You can change your code to be like below and wait for all the tasks to be completed.

var fileTasks = System.IO.Directory.GetFiles(_appSettings.DocumentsStorage, "*.xml").Select(async currentFile =>
                        {
                            try
                            {
                                XElement root = XElement.Load(currentFile); // or .Parse(string);
                                // rest o your code here
                                if (billDetails != null)
                                {
                                    if (billDataService.SaveBillDetail(billDetails) != null)
                                    {
                                        Console.WriteLine("SaveBillDetail done");
                                        await GetProfileDetails(billDetails);
                                    }
                                }
                             }
                          catch(exception ex) { //log exeption }
                       });

await Task.WhenAll(fileTasks);