异步函数WIthin异步循环

Question

我正在尝试运行一个异步方法，该方法有一个循环来从mySQL数据库加载一些数据。

Await函数不会停止其他任务的并发运行，但它们都是相互依赖的。

现在的结果是重复的DataGrid条目，但是DataGrid确实异步加载。在新的程序开始时，一切正常，没有任何重复-不确定为什么会发生这种情况！

如何在异步循环中调用返回数据的异步函数？

        private async void LoadAsync_ProviderReport()
        {
            Progress.Visibility = Visibility.Visible;
            DataGrid.Opacity = 0.3;
            string FromDate = FromDatePicker.Date.Value.ToString("yyyy-MM-dd");
            string ToDate = ToDatePicker.Date.Value.ToString("yyyy-MM-dd");
            ProviderReport.Clear();
            await Get_ProviderReport(FromDate, ToDate, DataGrid) ;
            Progress.Visibility = Visibility.Collapsed;
            DataGrid.Opacity = 1;
        }

private async Task<ObservableCollection<ProviderReport>> Get_ProviderReport(string FromDate, string ToDate, DataGrid DG)
        {
            ProviderReport.Clear();

            ProviderReport ptotal = new ProviderReport();
            AcrylicBrush brush2 = new AcrylicBrush();
            brush2.TintColor = Windows.UI.Color.FromArgb(0, 150, 150, 150);
            brush2.TintLuminosityOpacity = 0.6;
            brush2.BackgroundSource = 0;
            brush2.TintOpacity = 0.8;
            ptotal.ProvBrush = brush2;
            ptotal.Provider = "Practice Total";
            decimal PracticeProduction = 0;
            decimal PracticeAdjustments = 0;
            decimal PracticeWriteoffs = 0;
            decimal PracticeIncome = 0;
            decimal PracticeNetProduction = 0;
            decimal PracticeWorkedDays = 0;
            decimal PracticeWorkedHours = 0;
            decimal PracticeApptsNumbers = 0;
            decimal PracticeApptsHours = 0;
            decimal PracticeApptsBroken = 0;
            decimal PracticePtsSeen = 0;
            decimal PracticePtsReappointed = 0;

            foreach (DataRow ProviderRow in Providers.Rows)
            {               
                // Practice Total Row
                int ProvNum = Int32.Parse(ProviderRow["ProvNum"].ToString());
                Style ProvStyle = ProviderRow["ProvStyle"] as Style;
                Brush ProvBrush = ProviderRow["ProvBrush"] as Brush;
                string Provider = ProviderRow["Abbr"].ToString() + " - " + ProviderRow["FName"].ToString() + " " + ProviderRow["LName"].ToString();

                decimal Production = await SQL.Functions.GetValue(SQL.Queries.Production, FromDate, ToDate, ProvNum);
                decimal Adjustments = await SQL.Functions.GetValue(SQL.Queries.Adjustments, FromDate, ToDate, ProvNum);
                decimal Writeoffs = await SQL.Functions.GetValue(SQL.Queries.Writeoffs, FromDate, ToDate, ProvNum);
                decimal Income = await SQL.Functions.GetValue(SQL.Queries.Income, FromDate, ToDate, ProvNum);
                decimal NetProduction = Production - Adjustments + Writeoffs;
                decimal WorkedDays = await SQL.Functions.GetValue(SQL.Queries.WorkedDays, FromDate, ToDate, ProvNum);
                decimal WorkedHours = await SQL.Functions.GetValue(SQL.Queries.WorkedHours, FromDate, ToDate, ProvNum);
                decimal ApptsNumbers = await SQL.Functions.GetValue(SQL.Queries.ApptsNumbers, FromDate, ToDate, ProvNum);
                decimal ApptsHours = await SQL.Functions.GetValue(SQL.Queries.ApptsHours, FromDate, ToDate, ProvNum);
                decimal ApptsBroken = await SQL.Functions.GetValue(SQL.Queries.ApptsBroken, FromDate, ToDate, ProvNum);
                decimal PtsSeen = await SQL.Functions.GetValue(SQL.Queries.PtsSeen, FromDate, ToDate, ProvNum);
                decimal PtsReappointed = await SQL.Functions.GetValue(SQL.Queries.PtsReappointed, FromDate, ToDate, ProvNum);

                PrintButton.Content = "Loading :" + Provider;

                PracticeProduction += Production;
                PracticeAdjustments += Adjustments;
                PracticeWriteoffs += Writeoffs;
                PracticeIncome += Income;
                PracticeNetProduction += NetProduction;
                PracticeWorkedDays += WorkedDays;
                PracticeWorkedHours += WorkedHours;
                PracticeApptsNumbers += ApptsNumbers;
                PracticeApptsHours += ApptsHours;
                PracticeApptsBroken += ApptsBroken;
                PracticePtsSeen += PtsSeen;
                PracticePtsReappointed += PtsReappointed;

                //Each Selected Provider Row
                bool ProvSelected = Convert.ToBoolean(ProviderRow["Selected"]);
                if (ProvSelected == true)
                {
                    ProviderReport pr = new ProviderReport();
                    pr.ProvNum = ProvNum;
                    pr.ProvStyle = ProvStyle;
                    pr.ProvBrush = ProvBrush;
                    pr.Provider = Provider;
                    pr.Production = Production;
                    pr.Adjustments = Adjustments;
                    pr.Writeoffs = Writeoffs;
                    pr.Income = Income;
                    pr.NetProduction = NetProduction;
                    pr.WorkedDays = WorkedDays;
                    pr.WorkedHours = WorkedHours;
                    pr.ApptsNumbers = ApptsNumbers;
                    pr.ApptsHours = ApptsHours;
                    pr.ApptsBroken = ApptsBroken;
                    pr.PtsSeen = PtsSeen;
                    pr.PtsReappointed = PtsReappointed;
                    ProviderReport.Add(pr);
                }
            }

            //SubTotal Row
            decimal TotalProduction = 0;
            decimal TotalAdjustments = 0;
            decimal TotalWriteoffs = 0;
            decimal TotalIncome = 0;
            decimal TotalNetProduction = 0;
            decimal TotalWorkedDays = 0;
            decimal TotalWorkedHours = 0;
            decimal TotalApptsNumbers = 0;
            decimal TotalApptsHours = 0;
            decimal TotalApptsBroken = 0;
            decimal TotalPtsSeen = 0;
            decimal TotalPtsReappointed = 0;
            foreach (ProviderReport p in ProviderReport)
            {
                TotalProduction += p.Production;
                TotalAdjustments += p.Adjustments;
                TotalWriteoffs += p.Writeoffs;
                TotalIncome += p.Income;
                TotalNetProduction += p.NetProduction;
                TotalWorkedDays += p.WorkedDays;
                TotalWorkedHours += p.WorkedHours;
                TotalApptsNumbers += p.ApptsNumbers;
                TotalApptsHours += p.ApptsHours;
                TotalApptsBroken += p.ApptsBroken;
                TotalPtsSeen += p.PtsSeen;
                TotalPtsReappointed += p.PtsReappointed;
            }
            ProviderReport psubtotal = new ProviderReport();
            psubtotal.Provider = "Selected Providers Total";

            AcrylicBrush brush = new AcrylicBrush();
            brush.TintColor = Windows.UI.Color.FromArgb(0, 200, 200, 200);
            brush.TintLuminosityOpacity = 0.6;
            brush.BackgroundSource = 0;
            brush.TintOpacity = 0.8;
            psubtotal.ProvBrush = brush;

            psubtotal.Production = SubTotals.Production = TotalProduction;
            psubtotal.Adjustments = SubTotals.Adjustments = TotalAdjustments;
            psubtotal.Writeoffs = SubTotals.Writeoffs = TotalWriteoffs;
            psubtotal.Income = SubTotals.Income = TotalIncome;
            psubtotal.NetProduction = SubTotals.NetProduction = TotalNetProduction;
            psubtotal.WorkedDays = SubTotals.WorkedDays = TotalWorkedDays;
            psubtotal.WorkedHours = SubTotals.WorkedHours = TotalWorkedHours;
            psubtotal.ApptsNumbers = SubTotals.ApptsNumbers = TotalApptsNumbers;
            psubtotal.ApptsHours = SubTotals.ApptsHours = TotalApptsHours;
            psubtotal.ApptsBroken = SubTotals.ApptsBroken = TotalApptsBroken;
            psubtotal.PtsSeen = SubTotals.PtsSeen = TotalPtsSeen;
            psubtotal.PtsReappointed = SubTotals.PtsReappointed = TotalPtsReappointed;
            ProviderReport.Add(psubtotal);

            // Practice Total Row
            ptotal.Production = PracticeTotals.Production = PracticeProduction;
            ptotal.Adjustments = PracticeTotals.Adjustments = PracticeAdjustments;
            ptotal.Writeoffs = PracticeTotals.Writeoffs = PracticeWriteoffs;
            ptotal.Income = PracticeTotals.Income = PracticeIncome;
            ptotal.NetProduction = PracticeTotals.NetProduction = PracticeNetProduction;
            ptotal.WorkedDays = PracticeTotals.WorkedDays = PracticeWorkedDays;
            ptotal.WorkedHours = PracticeTotals.WorkedHours = PracticeWorkedHours;
            ptotal.ApptsNumbers = PracticeTotals.ApptsNumbers = PracticeApptsNumbers;
            ptotal.ApptsHours = PracticeTotals.ApptsHours = PracticeApptsHours;
            ptotal.ApptsBroken = PracticeTotals.ApptsBroken = PracticeApptsBroken;
            ptotal.PtsSeen = PracticeTotals.PtsSeen = PracticePtsSeen;
            ptotal.PtsReappointed = PracticeTotals.PtsReappointed = PracticePtsReappointed;
            ProviderReport.Add(ptotal);

            //Return Data
            DG.DataContext = ProviderReport;
            return ProviderReport;
        }

public async Task<decimal> GetValue(string query, string FromDate, string ToDate, int ProvNum)
        {                
            var ParametersName = new List<string>() { "@FromDate", "@ToDate", "@ProvNum" };
            var ParametersValue = new List<string>() { FromDate, ToDate, ProvNum.ToString() };
            var DT = new DataTable();
            DT = await Task.Run(() => ExecuteMySQLQuery(query, ParametersName, ParametersValue)); ;
            decimal Output = default(decimal);
            try
            {
                if (DT.Rows.Count == 1)
                { Output = Convert.ToDecimal(DT.Rows[0][0]); }
                else
                { Output = Convert.ToDecimal(DT.Rows.Count); }

            }
            catch (Exception ex)
            {
                Output = Convert.ToDecimal("0");
            }
            return (Output);
        }

“”“

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Answer 1

这是另一个多次调用Get_ProviderReport方法的方法！

似乎你已经找到了问题的原因，那么最根本的解决方案就是调整代码的结构，控制触发事件的顺序。

毕竟，多次调用一个方法意味着多次查询，这对软件的性能有很大的影响。

但也有一种直接的方法。我不知道你的ProviderReport是什么，但它看起来像一个集合。在将数据填充到DataGrid之前，我们可以使用LinQ执行重复数据消除。

在此之前，请确保已重写Equal ProviderReport**.**的方法

ProviderReport.Distinct();

DG.DataContext = ProviderReport;

诚挚的问候。