数据绑定不在Form.Controls集合中的DataGridView控件？ [英] Databinding a DataGridView control which is not in Form.Controls collection?

问题描述

我有一个继承自DataGridView的自定义控件。它增加了一些附加功能（导出每个单元格的内容）的控件。我想使用此功能，但不需要网格本身的UI。

所以，我创建一个自定义控件的实例，设置DataSource属性到DataTable的一个实例，以及...网格中没有列。我的DataTable具有列（和行），AutoGenerateColumns为true，但没有列出现在网格列集合中。事实上，它的自定义控件在这一点上变得无关紧要，因为DataGridView控件执行相同。

如果我将网格添加到表单的Controls集合中，数据绑定工作，网格有我的列。

为什么这样？

  public Form1（）
 {
 InitializeComponent（）; 
 
 DataTable dataTable = new DataTable（）{TableName =Bob}; 
 dataTable.Columns.Add（One，typeof（String））; 
 dataTable.Columns.Add（Two，typeof（String））; 
 dataTable.Columns.Add（Three，typeof（String））; 
 dataTable.Rows.Add（a，b，c）; 
 dataTable.Rows.Add（d，e，f）; 
 dataTable.Rows.Add（g，h，i）; 
 
 DataGridView grid = new DataGridView（）; 
 
 grid.DataSource = dataTable; 
 int n1 = grid.Columns.Count; //返回零
 
 this.Controls.Add（grid）; //为什么要这样做？ 
 
 grid.DataSource = null; 
 grid.DataSource = dataTable; 
 int n2 = grid.Columns.Count; //返回三个
} 
  

谢谢，
Ross

解决方案

David Hall的评论引导我进入这里，这导致我研究了网格的BindingContext。果然，它是空的，但是通过为网格控件创建一个新的BindingContext，将网格绑定到DataTable现在填充列集合。

 code> public Form1（）
 {
 InitializeComponent（）; 
 
 DataTable dataTable = new DataTable（）{TableName =Bob}; 
：
 
 DataGridView grid = new DataGridView {Name =Tom}; 
 
 grid.BindingContext = new BindingContext（）; 
 grid.DataSource = dataTable; 
 
 int n1 = grid.Columns.Count; //返回三个
} 
  

奇怪的是，您设置绑定上下文的顺序或数据源似乎并不重要！

I have a custom control which inherits from DataGridView. It augments the control with some additional functionality (which exports the contents of each cell). I would like to use this functionality, but don't need the UI of the grid itself.

So, I create an instance of the custom control, set the DataSource property to an instance of a DataTable, and... no columns in the grid. My DataTable has columns (and rows), AutoGenerateColumns is true, but no columns appear in the grid "Columns" collection. The fact that its a custom control becomes irrelevant at this point, because the DataGridView control does the same.

If I add the grid to a form's "Controls" collection, the data binding works, and the grid has my columns.

Why is that ?

  public Form1()
  {
     InitializeComponent();

     DataTable dataTable = new DataTable() { TableName = "Bob" };
     dataTable.Columns.Add("One",typeof(String));
     dataTable.Columns.Add("Two", typeof(String));
     dataTable.Columns.Add("Three", typeof(String));
     dataTable.Rows.Add("a", "b", "c");
     dataTable.Rows.Add("d", "e", "f");
     dataTable.Rows.Add("g", "h", "i");

     DataGridView grid = new DataGridView();

     grid.DataSource = dataTable;
     int n1 = grid.Columns.Count; // returns zero

     this.Controls.Add(grid); // why do I have to do this ?

     grid.DataSource = null;
     grid.DataSource = dataTable;
     int n2 = grid.Columns.Count; // returns three
  }

Thanks, Ross

解决方案

David Hall's comment led me to here, which led me to look into the BindingContext of the grid. Sure enough, it's null, but by creating a new BindingContext for the grid control, binding the grid to the DataTable now populates the "Columns" collection.

  public Form1()
  {
     InitializeComponent();

     DataTable dataTable = new DataTable() { TableName = "Bob" };
         :

     DataGridView grid = new DataGridView { Name = "Tom" };

     grid.BindingContext = new BindingContext();
     grid.DataSource = dataTable;

     int n1 = grid.Columns.Count; // returns three
  }

Curiously enough, the order in which you set the binding context or the data source appears not to matter !

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