It Seems that you have the same problem that discussed in this link
虽然乍一看我们没有看到这两个问题之间有任何关联，但由于您的 xaml 标记是正确的，我假设您在 VS 中收到此错误错误。
尝试在后面的代码中创建和处理 NodeLayouts。
您可以使用此代码进行测试：
数据源：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Collections.ObjectModel;
using System.Windows.Input;
using System.ComponentModel;
namespace DG
{
public class DataUtil
{
#region private members
#region private fields
private static ObservableCollection<Category> categories;
private static ObservableCollection<Product> products;
private static ObservableCollection<Category> categoriesAndProducts;
#endregion
#region private methods
private static ObservableCollection<Category> CreateCategories()
{
return new ObservableCollection<Category>
{
new Category
{
CategoryID = 1,
CategoryName = "Beverages",
Description = "Soft drinks, coffees, teas, beers, and ales"
},
new Category
{
CategoryID = 2,
CategoryName = "Condiments",
Description = "Sweet and savory sauces, relishes, spreads, and seasonings"
},
new Category
{
CategoryID = 3,
CategoryName = "Confections",
Description = "Desserts, candies, and sweet breads",
},
new Category
{
CategoryID = 4,
CategoryName = "Dairy Product",
Description = "Cheeses",
},
new Category
{
CategoryID = 5,
CategoryName = "Grains/Cereals",
Description = "Breads, crackers, pasta, and cereal",
},
new Category
{
CategoryID = 6,
CategoryName = "Meat/Poultry",
Description = "Prepared meats",
},
new Category
{
CategoryID = 7,
CategoryName = "Produce",
Description = "Dried fruit and bean curd",
},
new Category
{
CategoryID = 8,
CategoryName = "Seafood",
Description = "Seaweed and fish",
}
};
}
private static ObservableCollection<Product> CreateProducts()
{
return new ObservableCollection<Product>
{
new Product
{
ProductID = 1,
ProductName = "Chai",
CategoryID = 1,
QuantityPerUnit = "10 boxes x 20 bags",
UnitPrice = 18.0000m,
UnitsInStock = 39,
UnitsOnOrder = 0,
ReorderLevel = 10,
Discontinued = false
},
new Product
{
ProductID = 2,
ProductName = "Chang",
CategoryID = 1,
QuantityPerUnit = "24 - 12 oz bottles",
UnitPrice = 19.0000m,
UnitsInStock = 17,
UnitsOnOrder = 40,
ReorderLevel = 25,
Discontinued = false
},
new Product
{
ProductID = 24,
ProductName = "Guaraná Fantástica",
CategoryID = 1,
QuantityPerUnit = "12 - 355 ml cans",
UnitPrice = 4.5000m,
UnitsInStock = 20,
UnitsOnOrder = 0,
ReorderLevel = 0,
Discontinued = true
},
new Product
{
ProductID = 77,
ProductName = "Original Frankfurter grüne Soße",
CategoryID = 2,
QuantityPerUnit = "12 boxes",
UnitPrice = 13.0000m,
UnitsInStock = 32,
UnitsOnOrder = 0,
ReorderLevel = 15,
Discontinued = false
},
new Product
{
ProductID = 61,
ProductName = "Sirop d'érable",
CategoryID = 2,
QuantityPerUnit = "24 - 500 ml bottles",
UnitPrice = 28.5000m,
UnitsInStock = 113,
UnitsOnOrder = 0,
ReorderLevel = 25,
Discontinued = false
},
new Product
{
ProductID = 63,
ProductName = "Vegie-spread",
CategoryID = 2,
QuantityPerUnit = "15 - 625 g jars",
UnitPrice = 43.9000m,
UnitsInStock = 24,
UnitsOnOrder = 0,
ReorderLevel = 5,
Discontinued = false
},
new Product
{
ProductID = 16,
ProductName = "Pavlova",
CategoryID = 3,
QuantityPerUnit = "32 - 500 g boxes",
UnitPrice = 17.4500m,
UnitsInStock = 29,
UnitsOnOrder = 0,
ReorderLevel = 10,
Discontinued = false
},
new Product
{
ProductID = 19,
ProductName = "Teatime Chocolate Biscuits",
CategoryID = 3,
QuantityPerUnit = "10 boxes x 12 pieces",
UnitPrice = 9.2000m,
UnitsInStock = 25,
UnitsOnOrder = 0,
ReorderLevel = 5,
Discontinued = false
},
new Product
{
ProductID = 20,
ProductName = "Sir Rodney's Marmalade",
CategoryID = 3,
QuantityPerUnit = "30 gift boxes",
UnitPrice = 81.0000m,
UnitsInStock = 40,
UnitsOnOrder = 0,
ReorderLevel = 0,
Discontinued = false
},
new Product
{
ProductID = 69,
ProductName = "Gudbrandsdalsost",
CategoryID = 4,
QuantityPerUnit = "10 kg pkg.",
UnitPrice = 36.0000m,
UnitsInStock = 26,
UnitsOnOrder = 0,
ReorderLevel = 15,
Discontinued = false
},
new Product
{
ProductID = 71,
ProductName = "Flotemysost",
CategoryID = 4,
QuantityPerUnit = "10 - 500 g pkgs.",
UnitPrice = 21.5000m,
UnitsInStock = 26,
UnitsOnOrder = 0,
ReorderLevel = 0,
Discontinued = false
},
new Product
{
ProductID = 72,
ProductName = "Mozzarella di Giovanni",
CategoryID = 4,
QuantityPerUnit = "24 - 200 g pkgs.",
UnitPrice = 34.8000m,
UnitsInStock = 14,
UnitsOnOrder = 0,
ReorderLevel = 0,
Discontinued = false
},
new Product
{
ProductID = 22,
ProductName = "Gustaf's Knäckebröd",
CategoryID = 5,
QuantityPerUnit = "24 - 500 g pkgs.",
UnitPrice = 21.0000m,
UnitsInStock = 104,
UnitsOnOrder = 0,
ReorderLevel = 25,
Discontinued = false
},
new Product
{
ProductID = 23,
ProductName = "Tunnbröd",
CategoryID = 5,
QuantityPerUnit = "12 - 250 g pkgs.",
UnitPrice = 9.0000m,
UnitsInStock = 61,
UnitsOnOrder = 0,
ReorderLevel = 25,
Discontinued = false
},
new Product
{
ProductID = 53,
ProductName = "Perth Pasties",
CategoryID = 6,
QuantityPerUnit = "48 pieces",
UnitPrice = 32.8000m,
UnitsInStock = 0,
UnitsOnOrder = 0,
ReorderLevel = 0,
Discontinued = true
},
new Product
{
ProductID = 54,
ProductName = "Tourtière",
CategoryID = 6,
QuantityPerUnit = "16 pies",
UnitPrice = 7.4500m,
UnitsInStock = 21,
UnitsOnOrder = 0,
ReorderLevel = 10,
Discontinued = false
},
new Product
{
ProductID = 55,
ProductName = "Pâté chinois",
CategoryID = 6,
QuantityPerUnit = "24 boxes x 2 pies",
UnitPrice = 24.0000m,
UnitsInStock = 115,
UnitsOnOrder = 0,
ReorderLevel = 20,
Discontinued = false
},
new Product
{
ProductID = 28,
ProductName = "Rössle Sauerkraut",
CategoryID = 7,
QuantityPerUnit = "25 - 825 g cans",
UnitPrice = 45.6000m,
UnitsInStock = 26,
UnitsOnOrder = 0,
ReorderLevel = 0,
Discontinued = true
},
new Product
{
ProductID = 7,
ProductName = "Uncle Bob's Organic Dried Pears",
CategoryID = 7,
QuantityPerUnit = "12 - 1 lb pkgs.",
UnitPrice = 30.0000m,
UnitsInStock = 15,
UnitsOnOrder = 0,
ReorderLevel = 10,
Discontinued = false
},
new Product
{
ProductID = 14,
ProductName = "Tofu",
CategoryID = 7,
QuantityPerUnit = "40 - 100 g pkgs.",
UnitPrice = 23.2500m,
UnitsInStock = 35,
UnitsOnOrder = 0,
ReorderLevel = 0,
Discontinued = false
},
new Product
{
ProductID = 45,
ProductName = "Rogede sild",
CategoryID = 8,
QuantityPerUnit = "1k pkg.",
UnitPrice = 9.5000m,
UnitsInStock = 5,
UnitsOnOrder = 70,
ReorderLevel = 15,
Discontinued = false
},
new Product
{
ProductID = 46,
ProductName = "Spegesild",
CategoryID = 8,
QuantityPerUnit = "4 - 450 g glasses",
UnitPrice = 12.0000m,
UnitsInStock = 95,
UnitsOnOrder = 0,
ReorderLevel = 0,
Discontinued = false
},
new Product
{
ProductID = 58,
ProductName = "Escargots de Bourgogne",
CategoryID = 8,
QuantityPerUnit = "24 pieces",
UnitPrice = 13.2500m,
UnitsInStock = 62,
UnitsOnOrder = 0,
ReorderLevel = 20,
Discontinued = false
}
};
}
private static ObservableCollection<Category> CreateCategoriesAndProducts()
{
ObservableCollection<Category> retVal = CreateCategories();
ObservableCollection<Product> tempProducts = CreateProducts();
Category parentCategory = null;
foreach (Product p in tempProducts)
{
if (parentCategory == null || parentCategory.CategoryID != p.CategoryID)
{
parentCategory = retVal.First<Category>(category => category.CategoryID == p.CategoryID);
}
parentCategory.Products.Add(p);
}
return retVal;
}
#endregion
#endregion
#region public members
#region public properties
public static ObservableCollection<Category> Categories
{
get
{
if (categories == null)
categories = CreateCategories();
return categories;
}
}
public static ObservableCollection<Product> Products
{
get
{
if (products == null)
products = CreateProducts();
return products;
}
}
public static ObservableCollection<Category> CategoriesAndProducts
{
get
{
if (categoriesAndProducts == null)
categoriesAndProducts = CreateCategoriesAndProducts();
return categoriesAndProducts;
}
}
#endregion
#endregion
}
public class Category : INotifyPropertyChanged
{
#region private fields
private int categoryID;
private string categoryName;
private string description;
private ObservableCollection<Product> products;
#endregion
#region public properties
public int CategoryID
{
get
{
return this.categoryID;
}
set
{
if (this.categoryID != value)
{
this.categoryID = value;
OnPropertyChanged("CategoryID");
}
}
}
public string CategoryName
{
get
{
return this.categoryName;
}
set
{
if (this.categoryName != value)
{
this.categoryName = value;
OnPropertyChanged("CategoryName");
}
}
}
public string Description
{
get
{
return this.description;
}
set
{
if (this.description != value)
{
this.description = value;
OnPropertyChanged("Description");
}
}
}
public ObservableCollection<Product> Products
{
get
{
if (products == null)
{
products = new ObservableCollection<Product>();
}
return this.products;
}
}
#endregion
#region INotifyPropertyChanged Members
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged(string propertyName)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
#endregion
}
public class Product : INotifyPropertyChanged
{
#region INotifyPropertyChanged Members
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged(string propertyName)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
#endregion
#region private members
private int productID;
private string productName;
private int categoryID;
private string quantityPerUnit;
private decimal unitPrice;
private int unitsInStock;
private int unitsOnOrder;
private int reorderLevel;
private bool discontinued;
#endregion
#region public properties
public int ProductID
{
get
{
return this.productID;
}
set
{
if (this.productID != value)
{
this.productID = value;
OnPropertyChanged("ProductID");
}
}
}
public string ProductName
{
get
{
return this.productName;
}
set
{
if (this.productName != value)
{
this.productName = value;
OnPropertyChanged("ProductName");
}
}
}
public int CategoryID
{
get
{
return this.categoryID;
}
set
{
if (this.categoryID != value)
{
this.categoryID = value;
OnPropertyChanged("CategoryID");
}
}
}
public string QuantityPerUnit
{
get
{
return this.quantityPerUnit;
}
set
{
if (this.quantityPerUnit != value)
{
this.quantityPerUnit = value;
OnPropertyChanged("QuantityPerUnit");
}
}
}
public decimal UnitPrice
{
get
{
return this.unitPrice;
}
set
{
if (value < 0)
throw new Exception("Negative numbers are not allowed.");
this.unitPrice = value;
OnPropertyChanged("UnitPrice");
}
}
public int UnitsInStock
{
get
{
return this.unitsInStock;
}
set
{
if (value < 0)
throw new Exception("Negative numbers are not allowed.");
this.unitsInStock = value;
OnPropertyChanged("UnitsInStock");
}
}
public int UnitsOnOrder
{
get
{
return this.unitsOnOrder;
}
set
{
if (this.unitsOnOrder != value)
{
this.unitsOnOrder = value;
OnPropertyChanged("UnitsOnOrder");
}
}
}
public int ReorderLevel
{
get
{
return this.reorderLevel;
}
set
{
if (this.reorderLevel != value)
{
this.reorderLevel = value;
OnPropertyChanged("ReorderLevel");
}
}
}
public bool Discontinued
{
get
{
return this.discontinued;
}
set
{
if (this.discontinued != value)
{
this.discontinued = value;
OnPropertyChanged("Discontinued");
}
}
}
#endregion
}
}
使用此代码创建 xamdatatree：
MyTree.ItemsSource = DataUtil.CategoriesAndProducts;
NodeLayout mylayout = new NodeLayout();
mylayout.Key = "CategoryLayout";
mylayout.TargetTypeName = "Category";
mylayout.DisplayMemberPath = "CategoryName";
NodeLayout mylayout2 = new NodeLayout();
mylayout2.Key = "ProductLayout";
mylayout2.TargetTypeName = "Product";
mylayout2.DisplayMemberPath = "ProductName";
MyTree.GlobalNodeLayouts.Add(mylayout);
MyTree.GlobalNodeLayouts.Add(mylayout2);