我有两个组合框和 xml 文件，我想从 xml 填充组合框 1 中的服务器名称，并根据服务器名称填充第二个组合框答案

【问题标题】：i have two combo boxes and xml file, i want to populate server name in combo box 1 from xml and based on server name populate second combo box我有两个组合框和 xml 文件，我想从 xml 填充组合框 1 中的服务器名称，并根据服务器名称填充第二个组合框
【发布时间】：2016-02-12 08:59:46
【问题描述】：

XML：

<?xml version="1.0" encoding="utf-8"?>

<servers>
    <server>s2
        <database>db1</database>
        <database>db2</database>    

    </server>

    <server>s3
        <database>db3</database>
        <database>db4</database>    

    </server>

</servers>

我想根据服务器名称获取数据库并作为字符串类型列表返回。

查看：

此函数将服务器名称作为第一个组合框的参数，并基于将过滤数据库并填充第二个组合框

public List<string> GetDatabases(string serv)
       {          
           var item = from items in xdoc.Descendants("database")
                      where (string)items.Element("server") == serv
                      select items.Elements("database").ToList();                        
           foreach (var items in item)
           {
               lstDBName.Add(items.ToString());
           }               
           return lstDBName;

       }

【问题讨论】：

标签： c# xml wpf mvvm combobox

【解决方案1】：

您发布的 XML 无效。如果你用XML validator 测试它，你会看到它给出了这个错误：

Errors in the XML document: 
    1:  1   Content is not allowed in prolog.

您可以通过添加一个属性来存储服务器名称来轻松修复它，如下所示：

<?xml version="1.0" encoding="utf-8"?>
<servers>
    <server name="s2">
        <database>db1</database>
        <database>db2</database>    
    </server>
    <server name="s3">
        <database>db3</database>
        <database>db4</database>    
    </server>
</servers>

您可以像这样修改（并简化一点）您的代码：

public List<string> GetDatabases(string serv)
{
    XDocument xdoc = XDocument.Load("XMLFile1.xml");
    var lstDBName = (from items in xdoc.Descendants("server")
                     where items.Attribute("name").Value == serv
                     from item in items.Elements("database")
                     select item.Value)
                     .ToList();
    return lstDBName;
}

我从名为 XMLFile1.xml 的文件中读取方法内部的 XML，您可以更改该位，但您正在读取 XML。

此代码示例将按预期返回具有值“db1”和“db2”的两个字符串的列表

【讨论】：

【解决方案2】：

据我所知，您需要一些机制，在第一个组合中选择时会使用第一个组合相关数据更新第二个组合（基于您的问题名称：

我有两个组合框和 xml 文件，我想从 xml 填充组合框 1 中的服务器名称，并根据服务器名称填充第二个组合框

)。

这是一个基于两个可观察集合及其更新机制的解决方案。 1.Xaml代码：

<Window x:Class="SimpleDataGrid.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:simpleDataGrid="clr-namespace:SimpleDataGrid"
    Title="MainWindow" Height="350" Width="525">
<Window.DataContext>
    <simpleDataGrid:GridViewModel/>
</Window.DataContext>
<Grid >
    <DataGrid x:Name="SelectDataGrid" ItemsSource="{Binding Persons}" HorizontalAlignment="Left" VerticalAlignment="Top" AutoGenerateColumns="False">
        <DataGrid.Columns>
            <DataGridCheckBoxColumn x:Name="dgCheckBox" Header="Select" Width="45" Binding="{Binding IsChecked}"/>
            <DataGridTextColumn Header="FIRST NAME" Width="125" Binding="{Binding FNAME}"/>
            <DataGridTextColumn Header="LAST NAME" Width="125" Binding="{Binding LNAME}"/>
            <DataGridComboBoxColumn Header="Servers"
                                    DisplayMemberPath="ServerName" SelectedValueBinding="{Binding SelectedServer, UpdateSourceTrigger=PropertyChanged, Mode=TwoWay}">
                <DataGridComboBoxColumn.ElementStyle>
                    <Style TargetType="ComboBox">
                        <Setter Property="ItemsSource" Value="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type DataGridCell}}, Path=DataContext.Servers}"/>
                        <Setter Property="IsReadOnly" Value="True"/>
                    </Style>
                </DataGridComboBoxColumn.ElementStyle>
                <DataGridComboBoxColumn.EditingElementStyle>
                    <Style TargetType="ComboBox">
                        <Setter Property="ItemsSource" Value="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type DataGridCell}}, Path=DataContext.Servers}"/>
                    </Style>
                </DataGridComboBoxColumn.EditingElementStyle>
            </DataGridComboBoxColumn>
            <DataGridComboBoxColumn Header="Dbs" 
                                    DisplayMemberPath="DbName" 
                                    SelectedValueBinding="{Binding SelectedDb, UpdateSourceTrigger=PropertyChanged, Mode=TwoWay}">
                <DataGridComboBoxColumn.ElementStyle>
                    <Style TargetType="ComboBox">
                        <Setter Property="ItemsSource" Value="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type DataGridCell}}, Path=DataContext.Dbs}"/>
                        <Setter Property="IsReadOnly" Value="True"/>
                    </Style>
                </DataGridComboBoxColumn.ElementStyle>
                <DataGridComboBoxColumn.EditingElementStyle>
                    <Style TargetType="ComboBox">
                        <Setter Property="ItemsSource" Value="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type DataGridCell}}, Path=DataContext.Dbs}"/>
                    </Style>
                </DataGridComboBoxColumn.EditingElementStyle>
            </DataGridComboBoxColumn>
        </DataGrid.Columns>
    </DataGrid>
</Grid></Window>

2。提供解决方案的主模型代码。 UpdateDbCollection 方法可以调用您的 GetDatabases 方法，查询与服务器相关的数据库，将该数据放入“newDbs”列表并使用新数据更新第二个组合可观察集合当它添加一个新数据和改造一个旧数据时的方式。

    public class Person : BaseObservableObject
{
    private string _lName;
    private string _fName;
    private bool _checked;

    private object _selectedServer;
    private DbDetails _selectedDb;

    public Person()
    {
        Dbs = new ObservableCollection<DbDetails>();
        Servers = new ObservableCollection<ServerDetails>(new List<ServerDetails>
        {
            new ServerDetails
            {
                ServerName = "A",
                DbDetailses = new List<DbDetails>
                {
                    new DbDetails{DbName = "AA"},
                    new DbDetails{DbName = "AB"},
                    new DbDetails{DbName = "AC"},
                }
            },
             new ServerDetails
            {
                ServerName = "B",
                DbDetailses = new List<DbDetails>
                {
                    new DbDetails{DbName = "BA"},
                    new DbDetails{DbName = "BB"},
                    new DbDetails{DbName = "BC"},
                }
            },
             new ServerDetails
            {
                ServerName = "C",
                DbDetailses = new List<DbDetails>
                {
                    new DbDetails{DbName = "CA"},
                    new DbDetails{DbName = "CB"},
                }
            }
        });
    }
    public DbDetails SelectedDb
    {
        get { return _selectedDb; }
        set
        {
            _selectedDb = value;
            OnPropertyChanged();
        }
    }

    public object SelectedServer
    {
        get { return _selectedServer; }
        set
        {
            _selectedServer = value;
            OnPropertyChanged();
            UpdateDbCollection(SelectedServer as ServerDetails);
        }
    }

    private void UpdateDbCollection(ServerDetails serverDetails)
    {
        //here you can get your db details by selected server
        var newDbs = serverDetails.DbDetailses;
        newDbs.ForEach(details => Dbs.Add(details));
        var valuesToClear =
            Dbs.Where(
                existingDbDetails => newDbs.FirstOrDefault(dbDetails => existingDbDetails == dbDetails) == null).ToList();
        valuesToClear.ForEach(details => Dbs.Remove(details));
    }

    public ObservableCollection<ServerDetails> Servers { get; set; }

    public ObservableCollection<DbDetails> Dbs { get; set; }

    public bool IsChecked
    {
        get { return _checked; }
        set
        {
            _checked = value;
            OnPropertyChanged();
        }
    }

    public string LNAME
    {
        get { return _lName; }
        set
        {
            _lName = value;
            OnPropertyChanged();
        }
    }

    public string FNAME
    {
        get { return _fName; }
        set
        {
            _fName = value;
            OnPropertyChanged();
        }
    }
}

3。型号：

    public class ServerDetails:BaseObservableObject
{
    private string _serverName;

    public string ServerName
    {
        get { return _serverName; }
        set
        {
            _serverName = value;
            OnPropertyChanged();
        }
    }

    public List<DbDetails> DbDetailses { get; set; }
}

public class DbDetails:BaseObservableObject
{
    private string _dbName;

    public string DbName
    {
        get { return _dbName; }
        set
        {
            _dbName = value;
            OnPropertyChanged();
        }
    }
}

查看型号代码：

公共类 GridViewModel:BaseObservableObject {

public GridViewModel()
{
    var l = new List<Person>
    {
        new Person {FNAME = "John", LNAME = "W"},
        new Person {FNAME = "George", LNAME = "R"},
        new Person {FNAME = "Jimmy", LNAME = "B"},
        new Person {FNAME = "Marry", LNAME = "B"},
        new Person {FNAME = "Ayalot", LNAME = "A"},
    };
    Persons = new ObservableCollection<Person>(l);
}

public ObservableCollection<Person> Persons { get; set; }

}

BaseObservableObject 是 INotifyPropertyChanged 的简单实现。

希望对你有所帮助。谢谢问候，

【讨论】：