AppearanceAttribute.AppearanceItemType Property

Specifies the type of UI elements affected by the conditional appearance rule created using this attribute.

Namespace: DevExpress.ExpressApp.ConditionalAppearance

Assembly: DevExpress.Persistent.Base.v25.1.dll

NuGet Package: DevExpress.Persistent.Base

Declaration

C#

public string AppearanceItemType { get; set; }

VB.NET

Public Property AppearanceItemType As String

Property Value

Type	Description
String	The string representation of an AppearanceItemType enumeration value specifying the type of UI elements affected by the conditional appearance rule.

Remarks

To specify the UI element to be affected, apply the Appearance attribute to the required business class or business class property and use the AppearanceItemType and AppearanceAttribute.TargetItems attribute parameters. For details, refer to the Declare Conditional Appearance Rules in Code topic.

These are the following possible values for the AppearanceItemType attribute parameter:

• AppearanceItemType.ViewItem

  If you set the AppearanceItemType parameter to this value, AppearanceAttribute.TargetItems specifies properties affected by this attribute’s rule. Based on the AppearanceAttribute.Context parameter, properties are affected in List Views and/or Detail Views. In List Views, the rule affects the corresponding cells both in view and edit mode. In Detail Views, the rule affects the corresponding Property Editors. Static Text Detail View Items can be affected as well.

  Currently, XAF supports conditional appearance in Grid List Editors for all platforms and Tree List Editors for Windows Forms and ASP.NET Web Forms.

• AppearanceItemType.LayoutItem

  If you set the AppearanceItemType parameter to this value, AppearanceAttribute.TargetItems specifies Layout Item(s), Groups(), and Tabbed Group(s) affected by this attribute’s rule.

• AppearanceItemType.Action

  If you set the AppearanceItemType parameter to this value, AppearanceAttribute.TargetItems specifies Action(s) affected by this attribute’s rule.

This property is set to ViewItem by default.

Examples

Example 1.

The following code snippet changes the Product objects to maroon on a red background in List Views when the product’s price exceeds 50:

C# (EF Core)

using DevExpress.ExpressApp.ConditionalAppearance;
//...
[Appearance("RedPriceObject", AppearanceItemType = "ViewItem", TargetItems = "*",
    Criteria = "Price>50", Context = "ListView", BackColor = "Red",
        FontColor = "Maroon", Priority = 2)]
public class Product : BaseObject {
    public virtual string Name { get; set; }
    public virtual decimal Price { get; set; }
    public virtual ProductStatus Status { get; set; }
    public virtual Category Category { get; set; }
}

// Make sure that you use options.UseChangeTrackingProxies() in your DbContext settings.

C# (XPO)

using DevExpress.ExpressApp.ConditionalAppearance;
//...
[Appearance("RedPriceObject", AppearanceItemType = "ViewItem", TargetItems = "*",
    Criteria = "Price>50", Context = "ListView", BackColor = "Red",
        FontColor = "Maroon", Priority = 2)]
public class Product : BaseObject {
    public Product(Session session) : base(session) { }
    public string Name {
        //...
    }
    public decimal Price {
        //...
    }
    public ProductStatus Status {
        //...
    }
    public Category Category {
        //...
    }
}

Example 2.

The following code snippet changes the Category layout item’s caption in Product Detail Views to blue when the product’s category is “Seafood”:

C# (EF Core)

using DevExpress.ExpressApp.ConditionalAppearance;
//...
public class Product : BaseObject {
    [Appearance("CategoryColoredInDetailView", AppearanceItemType = "LayoutItem",
         TargetItems = "Category", Criteria = "Category = 'Seafood'", Context = "DetailView",
             FontColor = "Blue")]
    public virtual Category Category { get; set; }
}

[DefaultProperty(nameof(Name))]
public class Category : BaseObject {
    public virtual string Name { get; set; }
}

// Make sure that you use options.UseChangeTrackingProxies() in your DbContext settings.

C# (XPO)

using DevExpress.ExpressApp.ConditionalAppearance;
//...
public class Product : BaseObject {
    public Product(Session session) : base(session) { }
    [Appearance("CategoryColoredInDetailView", AppearanceItemType = "LayoutItem",
         TargetItems = "Category", Criteria = "Category = 'Seafood'", Context = "DetailView",
             FontColor = "Blue")]
    public Category Category {
        //...
    }
}
[DefaultProperty(nameof(Name))]
public class Category : BaseObject {
    public Category(Session session) : base(session) {}
    public string Name {
        //...
    }
}

Example 3.

The following code snippet disables a Product’s Deactivate Action when the Status property is set to “Inactive” in all Product Views. The Action ID specified in this rule contains the class name (“Product.Deactivate”) because the Deactivate Action is declared using the ActionAttribute. If you declare an Action in a Controller, specify its ID without the class name, for example, “Delete” or “Unlink”.

C# (EF Core)

using DevExpress.ExpressApp.ConditionalAppearance;
//...
[Appearance("ActionState", AppearanceItemType = "Action",
    TargetItems = "Product.Deactivate",
        Criteria = "Status = 'Inactive'", Context = "Any", Enabled = false)]
public class Product : BaseObject {
    public virtual ProductStatus Status { get; set; }
    [Action(PredefinedCategory.RecordEdit, Caption = "Deactivate Product...", AutoCommit = true,
     TargetObjectsCriteria = "Status = 'Active'",
      SelectionDependencyType = MethodActionSelectionDependencyType.RequireSingleObject)]
    public void Deactivate() {
        Status = ProductStatus.Inactive;
    }
}

// Make sure that you use options.UseChangeTrackingProxies() in your DbContext settings.

C# (XPO)

using DevExpress.ExpressApp.ConditionalAppearance;
//...
[Appearance("ActionState", AppearanceItemType = "Action",
    TargetItems = "Product.Deactivate",
        Criteria = "Status = 'Inactive'", Context = "Any", Enabled = false)]
public class Product : BaseObject {
    public Product(Session session) : base(session) { }
    public ProductStatus Status {
        //...
    }   
    [Action(PredefinedCategory.RecordEdit, Caption = "Deactivate Product...", AutoCommit = true,
     TargetObjectsCriteria = "Status = 'Active'",
      SelectionDependencyType = MethodActionSelectionDependencyType.RequireSingleObject)]
    public void Deactivate() {
        Status = ProductStatus.Inactive;
    }
}

Note

When you use a Conditional Appearance Rule (for example, the Appearance attribute) to hide an Action, it remains visible in List Views. XAF displays this Action as disabled. This helps avoid complex calculations that could hinder the application’s performance.

Additional examples are available in the Declare Conditional Appearance Rules in Code topic. See these examples in the Feature Center demo installed with XAF in the %PUBLIC%\Documents\DevExpress Demos 25.1\Components\XAF\FeatureCenter.NETFramework.XPO folder, or refer to the Feature Center demo online.

Implements

AppearanceItemType