无法填充DataGrid [英] Unable to populate DataGrid
问题描述
动态创建列，并希望使用字典元素进行绑定，可以动态修改/添加。在visual studio的调试输出中看不到错误。
我觉得我真的在这里缺少一些小事。
点击按钮不会填充第二列
ViewModel：
class DataGridAttachedPropertyViewModel {
public ObservableCollection< DataGridColumn> ColumnCollection {get;组; }
public ObservableCollection< AttachedPropertyEmployee>员工{get;组; }
public ICommand myCommand {get;组; }
public DataGridAttachedPropertyViewModel（）{
this.ColumnCollection = new ObservableCollection< DataGridColumn>（）;
DataGridTextColumn tc = new DataGridTextColumn（）;
tc.Header =Sample Column;
// tc.Binding = new Binding（name）;
Binding forCurrent = new Binding（SimpleDict [f]）;
forCurrent.Mode = BindingMode.TwoWay;
tc.Binding = forCurrent;
DataGridTextColumn tt = new DataGridTextColumn（）;
tt.Header =Column x;
// tc.Binding = new Binding（name）;
Binding forTheCurrent = new Binding（SimpleDict [x]）;
forTheCurrent.Mode = BindingMode.TwoWay;
tt.Binding = forTheCurrent;
myCommand = new DelegateCommand（ButtonBase_OnClick）;
this.ColumnCollection.Add（tc）;
this.SomEmployees = new ObservableCollection< AttachedPropertyEmployee>（）;
this.SomEmployees.Add（new AttachedPropertyEmployee（Rajat，Norwalk））;
this.SomEmployees.Add（new AttachedPropertyEmployee（Matthew，Norwalk））;
}
public void ButtonBase_OnClick（）{
foreach（SomEmployees中的var VARIABLE）{
VARIABLE.SimpleDict [x] =x;
}
}
}
AttachedPropertyEmployee。 cs
public class AttachedPropertyEmployee：INotifyPropertyChanged {
private Dictionary< string，string>箴言
public Dictionary< string，string> SimpleDict {
get {return this.dict; }
set
{
if（this.dict！= value）{
this.dict = value;
this.NotifyPropertyChanged（SimpleDict）;
}
}
}
public AttachedPropertyEmployee（string Name，string Address）{
this.SimpleDict = new Dictionary< string，string>（） ;
SimpleDict [f] =b;
this.name = Name;
this.address = Address;
}
public string name;
public string address {get;组; }
public event PropertyChangedEventHandler PropertyChanged;
public void NotifyPropertyChanged（string propName）{
if（this.PropertyChanged！= null）
this.PropertyChanged（this，new PropertyChangedEventArgs（propName））;
}
}
XAML： p>
< Window x：Class =LearnInteractivity.LearnDataGridAttachedProperty
xmlns =http://schemas.microsoft.com / winfx / 2006 / xaml / presentation
xmlns：x =http://schemas.microsoft.com/winfx/2006/xaml
xmlns：d =http://schemas.microsoft .com / expression / blend / 2008
xmlns：mc =http://schemas.openxmlformats.org/markup-compatibility/2006
xmlns：local =clr-namespace：LearnInteractivity
mc：Ignorable =d
Title =LearnDataGridAttachedPropertyHeight =300Width =300>
<！ -
放置一个datargrid和一个附加的属性，并更新列dynamincally。
- >
< StackPanel>
< DataGrid
本地：DataGridColumnsBehavior.BindableColumns ={Binding ColumnCollection}
x：Name =dgg
AutoGenerateColumns =False
ItemsSource ={Binding SomEmployees}>< / DataGrid>
< Button Content =填充Command ={Binding myCommand}>< / Button>
< / StackPanel>
我在这里看到两个问题。
第一个是 Dictionary< TKey，TValue> 不实现 INotifyCollectionChanged ，所以当您更改其中的值时，不会引发任何事件，UI不会知道。你可以找到一个 ObservableDictionary< K，V> 并使用它（IIRC有几个实现），或者你可以快速和脏的方式： p>
public void ButtonBase_OnClick（）{
foreach（SomEmployees中的var VARIABLE）{
VARIABLE.SimpleDict [x ] =x;
VARIABLE.NotifyPropertyChanged（SimpleDict）;
}
}
这将通知网格 SimpleDict 已更改。
第二个问题是在 DataGridAttachedPropertyViewModel 构造函数中，您忘了添加 tt 到 ColumnCollection 。
this.ColumnCollection。添加（tc）;
this.ColumnCollection.Add（tt）;
更多想法：
我会更加舒适地添加类似于 AttachedPropertyEmployee ：
public void SetColumValue string key，string value）{
SimpleDict [key] = value;
NotifyPropertyChanged（SimpleDict）;
}
然后在你的循环中使用它：
public void ButtonBase_OnClick（）{
foreach（SomEmployees中的var VARIABLE）{
VARIABLE.SetColumnValue（x，x） ;
}
}
顺便说一下，我会更改 SimpleDict to Dictionary< String，Object> 所以你可以支持更多的类型，而不仅仅是字符串，并留下格式化到UI。我可能会考虑在 SimpleDict 属性中显示一个 ReadOnlyDictionary< K，V> ，可写字典是一个私有字段 - 所以调用者别无选择，只能使用 SetColumnValue（k，v）设置列值。
I am trying to build a datagrid where columns are generated dynamically (this works fine) but I am unable to create bindings for the columns which update automatically (something like INotifyPropertyChanged).
Creating columns dynamically and want to use dictionary elements for binding which can be modified/added dynamically. No errors seen in debug output of visual studio.
I think I am really missing something minor here.
clicking button does not populate the second column
ViewModel:
class DataGridAttachedPropertyViewModel {
public ObservableCollection<DataGridColumn> ColumnCollection { get; set; }
public ObservableCollection<AttachedPropertyEmployee> SomEmployees { get; set; }
public ICommand myCommand { get; set; }
public DataGridAttachedPropertyViewModel() {
this.ColumnCollection = new ObservableCollection<DataGridColumn>();
DataGridTextColumn tc = new DataGridTextColumn();
tc.Header = "Sample Column";
// tc.Binding = new Binding("name");
Binding forCurrent = new Binding("SimpleDict[f]");
forCurrent.Mode = BindingMode.TwoWay;
tc.Binding = forCurrent;
DataGridTextColumn tt = new DataGridTextColumn();
tt.Header = "Column x";
// tc.Binding = new Binding("name");
Binding forTheCurrent = new Binding("SimpleDict[x]");
forTheCurrent.Mode = BindingMode.TwoWay;
tt.Binding = forTheCurrent;
myCommand = new DelegateCommand(ButtonBase_OnClick);
this.ColumnCollection.Add(tc);
this.SomEmployees = new ObservableCollection<AttachedPropertyEmployee>();
this.SomEmployees.Add(new AttachedPropertyEmployee("Rajat","Norwalk"));
this.SomEmployees.Add(new AttachedPropertyEmployee("Matthew", "Norwalk"));
}
public void ButtonBase_OnClick() {
foreach (var VARIABLE in SomEmployees) {
VARIABLE.SimpleDict["x"] = "x";
}
}
}
AttachedPropertyEmployee.cs
public class AttachedPropertyEmployee : INotifyPropertyChanged {
private Dictionary<string, string> dict;
public Dictionary<string, string> SimpleDict {
get { return this.dict; }
set
{
if (this.dict != value) {
this.dict = value;
this.NotifyPropertyChanged("SimpleDict");
}
}
}
public AttachedPropertyEmployee(string Name, string Address) {
this.SimpleDict = new Dictionary<string, string>();
SimpleDict["f"] ="b";
this.name = Name;
this.address = Address;
}
public string name;
public string address { get; set; }
public event PropertyChangedEventHandler PropertyChanged;
public void NotifyPropertyChanged(string propName) {
if (this.PropertyChanged != null)
this.PropertyChanged(this, new PropertyChangedEventArgs(propName));
}
}
XAML:
<Window x:Class="LearnInteractivity.LearnDataGridAttachedProperty"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:local="clr-namespace:LearnInteractivity"
mc:Ignorable="d"
Title="LearnDataGridAttachedProperty" Height="300" Width="300">
<!--
Put a datargrid and an attached property and update columns dynamincally.
-->
<StackPanel>
<DataGrid
local:DataGridColumnsBehavior.BindableColumns="{Binding ColumnCollection}"
x:Name="dgg"
AutoGenerateColumns="False"
ItemsSource="{Binding SomEmployees}"></DataGrid>
<Button Content="Populate" Command="{Binding myCommand}"></Button>
</StackPanel>
I see two problems here.
The first is that Dictionary<TKey,TValue> doesn't implement INotifyCollectionChanged, so when you change values in it, no event is raised and the UI never knows about it. You could look for an ObservableDictionary<K,V> and use that (IIRC there are a few implementations around), or you can do it the quick and dirty way:
public void ButtonBase_OnClick() {
foreach (var VARIABLE in SomEmployees) {
VARIABLE.SimpleDict["x"] = "x";
VARIABLE.NotifyPropertyChanged("SimpleDict");
}
}
That will notify the grid that SimpleDict has changed.
The second problem is that in the DataGridAttachedPropertyViewModel constructor, you forgot to add tt to ColumnCollection.
this.ColumnCollection.Add(tc);
this.ColumnCollection.Add(tt);
More thoughts:
I would be more comfortable adding something like this to AttachedPropertyEmployee:
public void SetColumValue(string key, string value) {
SimpleDict[key] = value;
NotifyPropertyChanged("SimpleDict");
}
And use that in your loop instead:
public void ButtonBase_OnClick() {
foreach (var VARIABLE in SomEmployees) {
VARIABLE.SetColumnValue("x", "x");
}
}
Incidentally, I'd change SimpleDict to Dictionary<String, Object> so you can support more types than just string, and leave formatting to the UI. And I might consider exposing a ReadOnlyDictionary<K,V> in the SimpleDict property, with the writable dictionary a private field -- so callers would have no choice but to use SetColumnValue(k,v) to set the column values.
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