创建样例xamdatatree错误

看来你有同样的问题，讨论在这个链接

虽然乍一看我们看不出这两个问题之间有任何关联但因为你的xaml标记是正确的，我假设你在vs

尝试在后面的代码中创建和处理NodeLayouts。

您可以使用以下代码进行测试:

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
}

}

用下面的代码创建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);