我们的应用程序在特定结构中生成大量结果列表。问题是，如果我想在DataGrid中显示它，我必须创建一个DataTable并将其设置为将使用内存的网格的dataSource。所以我创建了一个我创建的类的 BindingList （称为 myRow ），并且在myRow的结构中，我将所有需要的字段作为指向值的属性实际的结果列表。但问题是用户可以添加自定义列结果列表;我无法动态更改 myRow 的属性，我不想使用DataTable（因为它将与我的实际结果重复），如果我直接在dataGrid中创建自定义列，逐个单元地设置它们的值，内存中网格的大小非常高（我假设这是因为逐个单元格设置值会导致为每个单元格而不是更大的条件保存单元格的属性）。所以有没有人知道如何使用与使用属性作为列不同的策略创建一个行类，以便我可以在运行时动态设置列数？
答案 0 :(得分：3)
我认为可以使用TypeDescriptionProvider。
BAD新闻是：我之前从未这样做过，也无法提供太多帮助
//修改
我使用代码（参见上面的链接）来构建一个如何避免每个对象的字典的例子......
public class myRow
{
//your data storage class ...
public string txt { get; set; }
public int id { get; set; }
}
public class MyView:ICustomTypeDescriptor
{//your extendable view class ...
private static PropertyDescriptorCollection props = null;
static MyView()
{
TypeDescriptionProvider defaultProvider = TypeDescriptor.GetProvider(typeof(MyView));
props = new PropertyDescriptorCollection(defaultProvider.GetTypeDescriptor(typeof(MyView)).GetProperties().Cast<PropertyDescriptor>().ToArray(), true);
}
public static void addProperty(string name, DataTable dt, Func<DataRow, object> getter, Action<DataRow, object> setter, Func<DataTable, MyView, DataRow> rowSelector, Type PropType)
{
List<PropertyDescriptor> tmp;
if (props != null) tmp = props.Cast<PropertyDescriptor>().ToList();
else tmp = new List<PropertyDescriptor>();
PropertyDescriptor pd = TypeDescriptor.CreateProperty(typeof(MyView), name, PropType, null);
pd = new MyViewPropertyDescriptor(pd, dt, getter, setter, rowSelector, PropType);
tmp.Add(pd);
props = new PropertyDescriptorCollection(tmp.ToArray(), true);
}
//the data storage obj this view is referencing
public myRow obj;
public string TXT { // view-member known at compile time
get { return obj.txt; }
set { obj.txt = value; }
}
internal class MyViewPropertyDescriptor : PropertyDescriptor
{ // an example property descriptor that can link to data in a DataTable ...
DataTable dt;
Func<DataRow, object> getter;
Action<DataRow, object> setter;
Func<DataTable, MyView, DataRow> rowSelector;
Type type;
public MyViewPropertyDescriptor(PropertyDescriptor descr, DataTable dt, Func<DataRow, object> getter, Action<DataRow, object> setter, Func<DataTable, MyView, DataRow> rowSelector, Type PropType)
: base(descr)
{
this.dt = dt; // storage for additional data referenced by this property
this.getter = getter; //a getter that will take a DataRow, and extract the property value
this.setter = setter; //a setter that will take a DataRow and a value
this.rowSelector = rowSelector;//a row selector ... takes a dataset and the view object and has to return the assiciated datarow
this.type = PropType; // the type of this property
}
public override object GetValue(object component)
{
// using row selector and getter to return the current value ... you should add errorhandling here
return getter(rowSelector(dt, (MyView)component));
}
public override void SetValue(object component, object value)
{ // the setter ... needs errorhandling too
setter(rowSelector(dt, (MyView)component), value);
}
public override void ResetValue(object component)
{
}
public override bool CanResetValue(object component)
{
return false;
}
public override bool ShouldSerializeValue(object component)
{
return false;
}
public override Type PropertyType
{
get { return type; }
}
public override bool IsReadOnly
{
get { return false; }
}
public override Type ComponentType
{
get { return typeof(MyView); }
}
}
ICustomTypeDescriptor defaultDescriptor = TypeDescriptor.GetProvider(typeof(MyView)).GetTypeDescriptor(typeof(MyView));
AttributeCollection ICustomTypeDescriptor.GetAttributes()
{
return defaultDescriptor.GetAttributes();
}
string ICustomTypeDescriptor.GetClassName()
{
return defaultDescriptor.GetClassName();
}
string ICustomTypeDescriptor.GetComponentName()
{
return defaultDescriptor.GetComponentName();
}
TypeConverter ICustomTypeDescriptor.GetConverter()
{
return defaultDescriptor.GetConverter();
}
EventDescriptor ICustomTypeDescriptor.GetDefaultEvent()
{
return defaultDescriptor.GetDefaultEvent();
}
PropertyDescriptor ICustomTypeDescriptor.GetDefaultProperty()
{
return defaultDescriptor.GetDefaultProperty();
}
object ICustomTypeDescriptor.GetEditor(Type editorBaseType)
{
return defaultDescriptor.GetEditor(editorBaseType);
}
EventDescriptorCollection ICustomTypeDescriptor.GetEvents(Attribute[] attributes)
{
return defaultDescriptor.GetEvents(attributes);
}
EventDescriptorCollection ICustomTypeDescriptor.GetEvents()
{
return defaultDescriptor.GetEvents();
}
PropertyDescriptorCollection ICustomTypeDescriptor.GetProperties(Attribute[] attributes)
{
return props; // should really be filtered, but meh!
}
PropertyDescriptorCollection ICustomTypeDescriptor.GetProperties()
{
return props;
}
object ICustomTypeDescriptor.GetPropertyOwner(PropertyDescriptor pd)
{
return this;
}
}
和一个利用这个的小例子......
private void button1_Click(object sender, EventArgs e)
{
if (dataGridView1.DataSource == null)
{
List<myRow> data = new List<myRow>();
data.Add(new myRow { id = 1, txt = "test 1" });
data.Add(new myRow { id = 2, txt = "test 2" });
data.Add(new myRow { id = 3, txt = "test 3" });
DataTable dt = new DataTable();
dt.Columns.Add("id", typeof(int));
dt.Columns.Add("additionalData1", typeof(int));
dt.Columns.Add("additionalData2", typeof(int));
Random rnd = new Random();
foreach (var item in data)
{
dt.Rows.Add(new object[] { item.id, rnd.Next(), rnd.Next() });
}
MyView.addProperty("additionalData1", dt, row => row["additionalData1"], (row, val) => row["additionalData1"] = val, (tab, v) => tab.Rows.OfType<DataRow>().First(x => x["id"].Equals(v.obj.id)), typeof(int));
MyView.addProperty("additionalData2", dt, row => row["additionalData2"], (row, val) => row["additionalData2"] = val, (tab, v) => tab.Rows.OfType<DataRow>().First(x => x["id"].Equals(v.obj.id)), typeof(int));
dataGridView1.DataSource = new BindingList<MyView>(data.Select(x => new MyView { obj = x }).ToList());
}
}
当然，您需要提供更好的rowSelector或将DataTable替换为Hashtable或您想要的任何数据结构......只是一个示例