DevExpress XAF 查找列表视图及联级过滤

　　主要通过列表视图，实现联级过滤。只是对官方文件做了简单的代码复制，以后有机会再整理和修改。

初始化实现

　　使用the DataSourcePropertyAttribute 和 DataSourceCriteriaAttribute实现联级过滤。

using System.ComponentModel;
using DevExpress.Data.Filtering;
//... 
[DefaultClassOptions]
public class Order : BaseObject {
   public Order(Session session) : base(session) { }
   private Product product;
   public Product Product {
      get {
         return product;
      }
      set {
         SetPropertyValue("Product", ref product, value);
      }
   }
   private Accessory accessory;
   public Accessory Accessory {
      get {
         return accessory;
      }
      set {
         SetPropertyValue("Accessory", ref accessory, value);
      }
   }
}
public class Product : BaseObject {
   public Product(Session session) : base(session) { }
   private String productName;
   public String ProductName {
      get { 
         return productName;
      }
      set {
         SetPropertyValue("ProductName", ref productName, value);
      }
   }
   [Association("P-To-C")]
   public XPCollection<Accessory> Accessories {
      get { return GetCollection<Accessory>("Accessories"); }
   }
}
public class Accessory : BaseObject {
   public Accessory(Session session) : base(session) { }
   private String accessoryName;
   public String AccessoryName {
      get { 
         return accessoryName; 
      }
      set {
         SetPropertyValue("AccessoryName", ref accessoryName, value);
      }
   }
   private bool isGlobal;
   public bool IsGlobal {
      get {
         return isGlobal;
      }
      set {
         SetPropertyValue("IsGlobal", ref isGlobal, value);
      }
   }
   private Product product;
   [Association("P-To-C")]
   public Product Product { 
      get {
         return product;
      } 
      set {
         SetPropertyValue("Product", ref product, value);
      } 
   }
}

　　效果下图。

场景1 -使用指定集合属性中的对象填充查找

　　关键代码：[DataSourceProperty("Product.Accessories")]

[DefaultClassOptions]
public class Order : BaseObject {
   // ... 
   [DataSourceProperty("Product.Accessories")]
   public Accessory Accessory {
      get {
         return accessory;
      }
      set {
         SetPropertyValue("Accessory", ref accessory, value);
      }
   }
}

　　效果如下图：

场景2 -为Lookup属性集合应用标准

[DefaultClassOptions]
public class Order : BaseObject {
   // ... 
   [DataSourceCriteria("IsGlobal = true")]
   public Accessory Accessory {
      get {
         return accessory;
      }
      set {
         SetPropertyValue("Accessory", ref accessory, value);
      }
   }
}
public class Accessory : BaseObject {
      // ... 
   private bool isGlobal;
   public bool IsGlobal {
      get { return isGlobal; }
      set { 
         SetPropertyValue("IsGlobal", ref isGlobal, value);      
      }
   }
}

场景3 -如果指定的数据源属性为空，则使用备用标准

[DefaultClassOptions]
public class Order : BaseObject {
   // ... 
   [DataSourceProperty("Product.Accessories", 
      DataSourcePropertyIsNullMode.CustomCriteria, "IsGlobal = true")]
   public Accessory Accessory {
      get {
         return accessory;
      }
      set {
         SetPropertyValue("Accessory", ref accessory, value);
      }
   }
}

场景4 -手动填充查找

[DefaultClassOptions]
public class Order : BaseObject {
   // ... 
   // Set the AvailableAccessories collection as a data source for the Accessory property 
   [DataSourceProperty("AvailableAccessories")] 
   public Accessory Accessory {
      get {return accessory;}
      set {
         SetPropertyValue("Accessory", ref accessory, value);
      }
   }
   private XPCollection<Accessory> availableAccessories;
   [Browsable(false)] // Prohibits showing the AvailableAccessories collection separately 
   public XPCollection<Accessory> AvailableAccessories {
      get {
         if(availableAccessories == null) {
            // Retrieve all Accessory objects 
            availableAccessories = new XPCollection<Accessory>(Session);
            // Filter the retrieved collection according to current conditions 
            RefreshAvailableAccessories();
         }
         // Return the filtered collection of Accessory objects 
         return availableAccessories;
      }
   }
   private void RefreshAvailableAccessories() {
      if(availableAccessories == null)
         return;
      // Process the situation when the Product is not specified (see the Scenario 3 above) 
      if(Product == null) {
         // Show only Global Accessories when the Product is not specified 
         availableAccessories.Criteria = CriteriaOperator.Parse("[IsGlobal] = true");
      }
      else {
         // Leave only the current Product's Accessories in the availableAccessories collection 
         availableAccessories.Criteria = new BinaryOperator("Product", Product);
         if(IncludeGlobalAccessories == true) {
            // Add Global Accessories 
            XPCollection<Accessory> availableGlobalAccessories = 
               new XPCollection<Accessory>(Session);
            availableGlobalAccessories.Criteria = CriteriaOperator.Parse("[IsGlobal] = true");
            availableAccessories.AddRange(availableGlobalAccessories);
         }
      }
      // Set null for the Accessory property to allow an end-user  
      //to set a new value from the refreshed data source 
      Accessory = null;
   }
   public Product Product {
      get {return product;}
      set {
         SetPropertyValue("Product", ref product, value);
         // Refresh the Accessory Property data source 
         RefreshAvailableAccessories();
      }
   }
   private bool includeGlobalAccessories;
   [ImmediatePostData] //Use this attribute to refresh the Accessory  
   public bool IncludeGlobalAccessories {
      get {return includeGlobalAccessories;}
      set {
         if(includeGlobalAccessories != value) {
            includeGlobalAccessories = value;
            if(!IsLoading) {
               // Refresh the Accessory Property data source                     
               RefreshAvailableAccessories();
               SetPropertyValue("IncludeGlobalAccessories", ref includeGlobalAccessories, value);
            }
         }
      }
   }
}

 场景5 -根据当前对象的属性筛选Lookup属性集合

using DevExpress.Persistent.Base;
using DevExpress.Persistent.BaseImpl;
// ... 
public class Contact : Person {
    // ... 
    [DataSourceProperty("Department.Contacts", DataSourcePropertyIsNullMode.SelectAll)]
    [DataSourceCriteria("Position.Title = 'Manager' AND Oid != '@This.Oid'")]
    public Contact Manager {
        get {
            return manager;
        }
        set {
            SetPropertyValue("Manager", ref manager, value);
        }
    }
    // ... 
}

  参考网址

　　[1] https://documentation.devexpress.com/eXpressAppFramework/112681/Task-Based-Help/Filtering/How-to-Implement-Cascading-Filtering-for-Lookup-List-Views