问题与网格数据绑定 [英] Issue with Grid data binding
问题描述
我们的应用产生结果的一个具体结构的巨大的名单。问题是，如果我要显示它在DataGrid中，我要创建一个DataTable，并设置为将使用存储网格的数据源。所以，我创建了一个的BindingList类的我创建（称为 myRow ），并在myRow结构我有我需要为指向的值的属性的所有字段结果的实际列表。但问题是，用户可以添加结果自定义列清单;我不能改变的属性的 myRow 动态，我不希望使用一个DataTable（因为这将是我的实际结果的副本），如果我直接在DataGrid中创建自定义列设置其值细胞由细胞，在存储器中的栅格的尺寸变为非常高（我想这是因为设定值细胞由细胞导致细胞的特性要保存为每个小区，而不是一个较大的标准）。因此，没有人知道我怎么可以创建一个类行比使用属性为列不同的策略，这样我可以动态设置的列数在运行时？
Our application generate a huge list of result in a specific structure. The problem is that if I want to show it in a DataGrid, I have to create a DataTable and set it as the dataSource of the grid which will use memory. So I created a BindingList of a class that I created (called myRow) and in the structure of myRow I have all the fields that I require as properties pointing to the values in the actual list of results. But the problem is that users can add custom columns list of results; I can not change the properties of myRow dynamically, and I don't want to use a DataTable (because it will be a duplicate of my actual result) and if I create custom columns directly in the dataGrid and set their values cell-by-cell, the size of the grid in memory goes really high (I assume this is because setting values cell-by-cell causes the properties of cell to be saved for each cell instead of a bigger criteria). So does anyone know how can I create a class of row with a strategy different than using properties as columns, so that I can dynamically set the number of columns at runtime?
推荐答案
我认为这可以通过使用 TypeDescriptionProvider 。
i think this can be done by using a TypeDescriptionProvider.
<击>坏消息是：我从来没有这样做过，并不能提供太多的帮助
好消息是：我已经在这里找到一个例子：的DataGridView不显示对象它们实现ICustomTypeDescriptor
the GOOD news is: i've found an example here: DataGridView not showing properites of objects which implement ICustomTypeDescriptor
//修改
我使用的代码（见的性质在上面的链接）来构建一个例子，如何避免每个对象字典...
i used the code (see link above) to build an example how to avoid the dictionary per object ...
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;
}
}
和一个小例子，使得使用这...
and a little example that makes use of this ...
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，你将要提供更好的rowSelector或你想要一个Hashtable或任何数据结构替换数据表...只是一个例子。
of course you will want to provide a better rowSelector or replace the DataTable with a Hashtable or whatever datastructure you want ... just an example
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