在使用itemssource之前，items集合必须为空 [英] The items collection must be empty before using itemssource

问题描述

我正在尝试数据绑定两个itemssources。我想我必须重新排列我的xaml。但我不知道该怎么做。

I'm trying to data bind two itemssources. I assume I have to rearrange my xaml. But I don't know how to do this.

如何解决这个问题？

我的xaml：

Page x:Class="Dienstverplaatsing.Page1"
      xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
      xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
      xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
      xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
      xmlns:local="clr-namespace:Dienstverplaatsing"
      mc:Ignorable="d" 
      d:DesignHeight="450"
      Title="Page1" >

    <Grid Margin="0,0,0,10">
        <DockPanel>
            <Menu DockPanel.Dock="Top">
                <MenuItem Header="_Bestand">
                    <MenuItem Header="_Werknemerslijst" />
                    <MenuItem Header="_Werknemer toevoegen" />
                    <MenuItem Header="_Afsluiten" />
                </MenuItem>
                <MenuItem Header="_Persoonlijke gegevens" Click="MenuItem_Click">


                </MenuItem>
                <MenuItem Header="_Verplaatsingen goedkeuren">
                    
                    
                </MenuItem>
                <MenuItem Header="_CSV Genereren">


                </MenuItem>
            </Menu>
            
        </DockPanel>
        <TabControl Name="tcYear" Margin="10,20,10,10" TabStripPlacement="left">
            <TabItem Header="{Binding Year}">
                <TabControl Name="tcMonth" Margin="10,20,10,10" TabStripPlacement="Bottom">
                    <TabItem Header="{Binding Month}">
                        <DataGrid Name="dgVerplaatsingen" AutoGenerateColumns="False"  ColumnWidth="*" CanUserReorderColumns="False" CanUserAddRows="False" >
                            <DataGrid.ColumnHeaderStyle>
                                <Style TargetType="DataGridColumnHeader">
                                    <Setter Property="ContentTemplate">
                                        <Setter.Value>
                                            <DataTemplate>
                                                <TextBlock TextWrapping="Wrap" Text="{Binding}"></TextBlock>
                                            </DataTemplate>
                                        </Setter.Value>
                                    </Setter>
                                </Style>
                            </DataGrid.ColumnHeaderStyle>
                            <DataGrid.Columns >

                                <DataGridTextColumn Header="Datum" Binding="{Binding Datum,StringFormat=d}" IsReadOnly="True" Width="75"  />


                                <DataGridTextColumn Header="Omschrijving" Binding="{Binding Omschrijving}" Width="150">
                                    <DataGridTextColumn.ElementStyle>
                                        <Style>
                                            <Setter Property="TextBlock.TextWrapping" Value="Wrap" />
                                            <Setter Property="TextBlock.TextAlignment" Value="Left"/>
                                        </Style>
                                    </DataGridTextColumn.ElementStyle>
                                </DataGridTextColumn>



                                <DataGridTextColumn Header="Km auto" Binding="{Binding Datum}" Width="75" />
                                <DataGridTextColumn Header="Km fiets" Binding="{Binding Datum}" Width="75" />
                                <DataGridTextColumn Header="Bedrag parkeren" Binding="{Binding Datum}" Width="75" />
                                <DataGridTextColumn Header="Bedrag openbaar vervoer" Binding="{Binding Datum}" Width="75" />
                                <DataGridTextColumn Header="Totaal bedrag" Binding="{Binding Datum}" Width="75" IsReadOnly="True" />
                                <DataGridTextColumn Header="Aantal Auto" Binding="{Binding Datum}" Width="75" />
                                <DataGridTextColumn Header="Aantal fiets" Binding="{Binding Datum}" Width="75" />


                            </DataGrid.Columns>
                        </DataGrid>
                    </TabItem>
                </TabControl>
            </TabItem>
                
        </TabControl>
        
    </Grid>
</Page>

My C sharp： 

My C sharp: 

List<Kalendar> calendar = new List<Kalendar>
                 {
                new Kalendar() { Year={ 2017,2018,2019 }, Month={ "Jan", "febr", "mrt", "april", "juli", "augustus", "september", "oktober", "november", "december"} }

            };
            tcYear.ItemsSource = calendar;

            List<Verplaatsing> Verplaatsingen = new List<Verplaatsing>
            {
                new Verplaatsing() { Datum = new DateTime(2018, 2, 5), KmAuto = 1 },
                new Verplaatsing() { Datum = new DateTime(2018, 2, 15), KmAuto = 2 },
                new Verplaatsing() { Datum = new DateTime(2018, 2, 25), KmAuto = 3 }
            };

dgVerplaatsingen.ItemsSource = Verplaatsingen ;

dgVerplaatsingen.ItemsSource = Verplaatsingen;

推荐答案

您在tcYear的代码中设置了itemsource，但已经在XAML中定义了一个标签。  

You are setting the itemsource in code for tcYear but already have a tab defined in XAML.  

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