Wpf 在dgv加载时显示加载动画

更新代码。我认为它很接近，但dgv没有加载任何数据

公开课密室作业 Public sqlcon As String=My.Settings.New\u Assembly\u AccessConnectionString 公共con作为新的SqlConnection（sqlcon） 作为字符串的公共作业

Public Async Function GetDataAsync(ByVal sql As String, ByVal sqlcon As String) As Task(Of DataTable)
    Dim dt As New DataTable
    Dim cmd As New SqlCommand(sql, con)
    Using da = New SqlDataAdapter(sql, sqlcon)
        da.SelectCommand = cmd
        cmd.Parameters.AddWithValue("@Job2", job)

        Await Task.Run(Function()
                           da.Fill(dt)
                       End Function)
    End Using

    Return dt
End Function


Public Async Sub Button_Click(sender As Object, e As RoutedEventArgs)
    Refresh.Visibility = Windows.Visibility.Visible
    txtJob.IsEnabled = False
    btnEnter.IsEnabled = False

    Try
        job = txtJob.Text
        Dim sqlcon As String = My.Settings.New_Assembly_AccessConnectionString
        Dim sql As String
       
        sql = "SELECT isnull(p.[CLASS],j.class) as 'CLASS',isnull([SERIAL_NUMBER],left(year(d.cup_mfg_date),2) + d.cup_serial) as SERIAL, " & _
                              "isnull([CUP_DATE],d.cup_mfg_date) as CUPDATE, isnull([CUP_PART_NUM],left([Cup#],charindex('-',Cup#)-1)) as PARTNUM, isnull(p.[LATERAL_VALUE], " & _
                               "d.lateral_value * 10000) as LATVALUE, isnull([LAT_UPPER],0) as LAT_UPPER,isnull([LAT_LOWER],0) as LAT_LOWER, " & _
                               "isnull(p.[BEFORE_WEIGHT],0) as BEFORE_WEIGHT, isnull(p.[AFTER_WEIGHT],0) as AFTER_WEIGHT,isnull([GREASE_UPPER],0) as GREASE_UPPER, " & _
                               "isnull([GREASE_LOWER],0) as GREASE_LOWER,isnull(p.[SPACER_MEASURE], d.Spacer_Measure) as SPACER,isnull([QTY_SPACER_CHANGE],0) as 'CHANGES', " & _
                               "isnull([LATERAL_DATE_TIME],'1999-11-11 11:11:11.111') as LATERAL_DATE_TIME, " & _
                               "isnull([GREASE_DATE_TIME],'1999-11-11 11:11:11.111') as GREASE_DATE_TIME, isnull([LINE_NUM],d.linenum) as LINE, " & _
                               "isnull(BAD_PART, 'BAD_INFO') as Result, isnull([AIR_PRESSURE1], 0) as PRESSURE " & _
                               "FROM [NB_ASSEMBLY].[dbo].[PieceData] p full outer JOIN New_Assembly_Access.dbo.Tbl_Data AS d " & _
                               "ON substring(d.zbarcode,3,6) = right(p.serial_number,6) and month(d.cup_mfg_date) = month(p.cup_date) and " & _
                               "right(d.zbarcode,10) = right(p.cup_part_num,10) join new_assembly_Access.dbo.tbl_job j on j.job# = d.job# where d.job# = @Job2"

        con.Open()
        Dim data = Await GetDataAsync(sql, sqlcon)

        dgvJob.DataContext = data
        dgvJob.AutoGenerateColumns = True
        dgvJob.CanUserAddRows = False

    Catch ex As Exception

    End Try
    Refresh.Visibility = Windows.Visibility.Hidden

End Sub

Private Sub Window_Loaded(sender As Object, e As RoutedEventArgs)
    Refresh.Visibility = Windows.Visibility.Hidden
    txtJob.Focus()

End Sub

---

End Class

这是您动态修改的代码，从这里开始，因为我不知道是否运行良好，或者是否需要在没有数据库和其他参数的情况下进行更改

Public con As New SqlConnection
Public job As String

Private Sub ReadDatabase()

    Dim bgThread As Threading.Thread = New Threading.Thread(Sub()

                                                                Dim sqlcon As String = My.Settings.New_Assembly_AccessConnectionString
                                                                Dim sql As New SqlCommand
                                                                Dim da As New SqlDataAdapter
                                                                Dim ds As New DataSet

                                                                Using con = New SqlConnection(sqlcon)
                                                                    con.Open()

                                                                    sql = New SqlCommand("SELECT isnull(p.[CLASS],j.class) as 'CLASS',isnull([SERIAL_NUMBER],left(year(d.cup_mfg_date),2) + d.cup_serial) as SERIAL, " &
                                                                                              "isnull([CUP_DATE],d.cup_mfg_date) as CUPDATE, isnull([CUP_PART_NUM],left([Cup#],charindex('-',Cup#)-1)) as PARTNUM, isnull(p.[LATERAL_VALUE], " &
                                                                                              "d.lateral_value * 10000) as LATVALUE, isnull([LAT_UPPER],0) as LAT_UPPER,isnull([LAT_LOWER],0) as LAT_LOWER, " &
                                                                                              "isnull(p.[BEFORE_WEIGHT],0) as BEFORE_WEIGHT, isnull(p.[AFTER_WEIGHT],0) as AFTER_WEIGHT,isnull([GREASE_UPPER],0) as GREASE_UPPER, " &
                                                                                              "isnull([GREASE_LOWER],0) as GREASE_LOWER,isnull(p.[SPACER_MEASURE], d.Spacer_Measure) as SPACER,isnull([QTY_SPACER_CHANGE],0) as 'CHANGES', " &
                                                                                              "isnull([LATERAL_DATE_TIME],'1999-11-11 11:11:11.111') as LATERAL_DATE_TIME, " &
                                                                                              "isnull([GREASE_DATE_TIME],'1999-11-11 11:11:11.111') as GREASE_DATE_TIME, isnull([LINE_NUM],d.linenum) as LINE, " &
                                                                                              "isnull(BAD_PART, 'BAD_INFO') as Result, isnull([AIR_PRESSURE1], 0) as PRESSURE " &
                                                                                              "FROM [NB_ASSEMBLY].[dbo].[PieceData] p full outer JOIN New_Assembly_Access.dbo.Tbl_Data AS d " &
                                                                                              "ON substring(d.zbarcode,3,6) = right(p.serial_number,6) and month(d.cup_mfg_date) = month(p.cup_date) and " &
                                                                                              "right(d.zbarcode,10) = right(p.cup_part_num,10) join new_assembly_Access.dbo.tbl_job j on j.job# = d.job# where d.job# = @Job2", con)


                                                                    sql.Parameters.AddWithValue("@Job2", job)
                                                                    da.SelectCommand = sql

                                                                    Dim dt As New DataTable
                                                                    da.Fill(dt)
                                                                    Invoke(Sub()
                                                                               dgvJob.DataContext = dt.DefaultView
                                                                               dgvJob.AutoGenerateColumns = True
                                                                               dgvJob.CanUserAddRows = False
                                                                           End Sub)


                                                                End Using


                                                            End Sub) With {
        .IsBackground = True
                                        }
    bgThread.Start()

End Sub

Public Sub Button_Click(sender As Object, e As RoutedEventArgs)

    txtJob.IsEnabled = False
    btnEnter.IsEnabled = False
    job = txtJob.Text

    ReadDatabase()

End Sub

Private Sub Window_Loaded(sender As Object, e As RoutedEventArgs)
    txtJob.Focus()
End Sub

---

我建议你清理一下你的代码，让方法只做一件事——不要有一个ReadDatabase，它也会摆弄控件等等

DataAdapter可以获取一个sql字符串和一个连接字符串，它知道如何建立连接和打开连接等。它会整理好一切，然后将所有这些交给DA

可能会把这个庞大的SQL字符串放到一个资源文件中

Private Async Function GetComponentsDataTable() as Task(Of DataTable)

    Dim con As String = My.Settings.New_Assembly_AccessConnectionString
    Dim sql as String = "SELECT isnull(p.[CLASS],j.class) as 'CLASS',isnull([SERIAL_NUMBER],left(year(d.cup_mfg_date),2) + d.cup_serial) as SERIAL, " & _
                                      "isnull([CUP_DATE],d.cup_mfg_date) as CUPDATE, isnull([CUP_PART_NUM],left([Cup#],charindex('-',Cup#)-1)) as PARTNUM, isnull(p.[LATERAL_VALUE], " & _
                                      "d.lateral_value * 10000) as LATVALUE, isnull([LAT_UPPER],0) as LAT_UPPER,isnull([LAT_LOWER],0) as LAT_LOWER, " & _
                                      "isnull(p.[BEFORE_WEIGHT],0) as BEFORE_WEIGHT, isnull(p.[AFTER_WEIGHT],0) as AFTER_WEIGHT,isnull([GREASE_UPPER],0) as GREASE_UPPER, " & _
                                      "isnull([GREASE_LOWER],0) as GREASE_LOWER,isnull(p.[SPACER_MEASURE], d.Spacer_Measure) as SPACER,isnull([QTY_SPACER_CHANGE],0) as 'CHANGES', " & _
                                      "isnull([LATERAL_DATE_TIME],'1999-11-11 11:11:11.111') as LATERAL_DATE_TIME, " & _
                                      "isnull([GREASE_DATE_TIME],'1999-11-11 11:11:11.111') as GREASE_DATE_TIME, isnull([LINE_NUM],d.linenum) as LINE, " & _
                                      "isnull(BAD_PART, 'BAD_INFO') as Result, isnull([AIR_PRESSURE1], 0) as PRESSURE " & _
                                      "FROM [NB_ASSEMBLY].[dbo].[PieceData] p full outer JOIN New_Assembly_Access.dbo.Tbl_Data AS d " & _
                                      "ON substring(d.zbarcode,3,6) = right(p.serial_number,6) and month(d.cup_mfg_date) = month(p.cup_date) and " & _
                                      "right(d.zbarcode,10) = right(p.cup_part_num,10) join new_assembly_Access.dbo.tbl_job j on j.job# = d.job# where d.job# = @Job2"

    Using da as New SqlDataAdapter(sql, con)

        da.SelectCommand.Parameters.AddWithValue("@Job2", job) 'see https://blogs.msmvps.com/jcoehoorn/blog/2014/05/12/can-we-stop-using-addwithvalue-already/'
        Dim dt As New DataTable
        Await Task.Run(Sub() da.Fill(dt))           'also, see note from AlexB
        Return dt
    End Using

End Sub

Public Async Sub Button_Click(sender As Object, e As RoutedEventArgs)

    txtJob.IsEnabled = False
    btnEnter.IsEnabled = False


    Dim dt = Await GetComponentsDataTable()

    dgvJob.AutoGenerateColumns = True
    dgvJob.DataContext = dt.DefaultView
    dgvJob.CanUserAddRows = False

End Sub

Private Sub Window_Loaded(sender As Object, e As RoutedEventArgs)
    txtJob.Focus()

End Sub

---

开始阅读关于。您的

ReadDatabase（）

应该是

async

读取数据库的值。在UI中，等待对ReadDatabase（）的调用。提示：没有人会为您编写完整的代码。如果您有特定的问题或例外，请回来。我为没有发布我的特定问题而道歉。我真的不知道该贴哪一张，甚至连一张都没有。我和Backgroundworker至少试过几次，都被激怒了，并且删除了所有内容。然后发现一些使用异步的例子，我无法开始工作…所以我再次删除了所有内容。我无意冒犯。这只是一个提醒。看来你从Caius那里得到了一个有效的解决方案。我建议您真正深入到async/Wait主题，并尝试了解它是如何工作的。感谢您的回复。您的代码给了我一个dt（datatable）的空引用异常。啊，在GetComponentDataTable的末尾遗漏了一个

返回dt

，现在添加了。另外，您应该进入项目属性/设置，并在“编译”选项卡上启用“严格”选项。它可能会导致出现其他错误；这是设计-解决它们，因为它们是等待发生的bug。“Option Strict Off”=“让开发人员轻松自如地处理几乎所有的事情，希望在运行时不会发生任何爆炸”。Option Strict On=“执行更严格的代码准确性检查”。后者总是比前者更好-在设计时会发现这一点。答案很好，但我个人会在这个场景中明确使用

ConfigureAwait（true）

，因为您处理的是UI。我知道这是多余的，因为默认情况下它是真实的，但对于学习和文档编制来说，这是一个很好的行为。