Disable and Hide Property Editors Based on a Business Rule

• Oct 23, 2023
• 4 minutes to read

XAF is shipped with the Conditional Appearance module. One of the features provided by this module is an option to disable/enable and show/hide Property Editors based on business rules. This topic contains step-by-step instructions that demonstrate how the Conditional Appearance module can be used for this purpose. Several appearance rules will be created to dynamically hide and disable Property Editors.

Note

See more examples on how to use the Conditional Appearance in the Feature Center demo installed with XAF in the %PUBLIC%\Documents\DevExpress Demos 24.2\Components\XAF\FeatureCenter.NETFramework.XPO folder, or refer to the Feature Center demo online.

Use the DevExpress v24.2 XAF Template Gallery template to create a new XAF Solution. Add the Conditional Appearance module to the module project. To do this, open the MySolution.Module\Module.cs (Module.vb) file and add the following code to the Module constructor:

C#

using DevExpress.ExpressApp.ConditionalAppearance;
// ...
namespace MySolution.Module {
    public sealed partial class MySolutionModule : ModuleBase {
        public MySolutionModule() {
            // ...
            RequiredModuleTypes.Add(typeof(ConditionalAppearanceModule));
        }
    }
}

VB.NET

Imports DevExpress.ExpressApp.ConditionalAppearance
' ...
Namespace MySolution.Module
    Public NotInheritable Partial Class MySolutionModule
        Inherits ModuleBase

        Public Sub New()
            ' ...
            RequiredModuleTypes.Add(GetType(ConditionalAppearanceModule))
        End Sub
    End Class
End Namespace

In .NET Framework projects, you can alternatively invoke the Module Designer for the module project and drag the ConditionalAppearanceModule item from the Toolbox to the Required Modules panel.

Declare the Contact business class in the solution’s Module Project. You can use the XPO Business Object template for this purpose. Replace the auto-generated class’ code with the following.

C# (EF Core)

[DefaultClassOptions]
[ImageName("BO_Person")]
public class Contact : BaseObject {
    public virtual string Name { get; set; }
    public virtual bool IsMarried { get; set; }
    public virtual string SpouseName { get; set; }
    public virtual string Address1 { get; set; }
    public virtual string Address2 { get; set; }
}

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

C# (XPO)

[DefaultClassOptions]
[ImageName("BO_Person")]
public class Contact : BaseObject {
    public Contact(Session session) : base(session) { }        
    public string Name {
        get { return GetPropertyValue<string>(nameof(Name)); }
        set { SetPropertyValue<string>(nameof(Name), value); }
    }
    public bool IsMarried {
        get { return GetPropertyValue<bool>(nameof(IsMarried)); }
        set { SetPropertyValue<bool>(nameof(IsMarried), value); }
    }
    public string SpouseName {
        get { return GetPropertyValue<string>(nameof(SpouseName)); }
        set { SetPropertyValue<string>(nameof(SpouseName), value); }
    }
    public string Address1 {
        get { return GetPropertyValue<string>(nameof(Address1)); }
        set { SetPropertyValue<string>(nameof(Address1), value); }
    }
    public string Address2 {
        get { return GetPropertyValue<string>(nameof(Address2)); }
        set { SetPropertyValue<string>(nameof(Address2), value); }
    }
}

VB.NET (XPO)

Public Class Contact
    Inherits BaseObject
    Public Sub New(ByVal session As Session)
        MyBase.New(session)
    End Sub
    Public Property Name() As String
        Get
            Return GetPropertyValue(Of String)(NameOf(Name))
        End Get
        Set(ByVal value As String)
            SetPropertyValue(Of String)(NameOf(Name), value)
        End Set
    End Property
    Public Property IsMarried() As Boolean
        Get
            Return GetPropertyValue(Of Boolean)(NameOf(IsMarried))
        End Get
        Set(ByVal value As Boolean)
            SetPropertyValue(Of Boolean)(NameOf(IsMarried), value)
        End Set
    End Property
    Public Property SpouseName() As String
        Get
            Return GetPropertyValue(Of String)(NameOf(SpouseName))
        End Get
        Set(ByVal value As String)
            SetPropertyValue(Of String)(NameOf(SpouseName), value)
        End Set
    End Property
    Public Property Address1() As String
        Get
            Return GetPropertyValue(Of String)(NameOf(Address1))
        End Get
        Set(ByVal value As String)
            SetPropertyValue(Of String)(NameOf(Address1), value)
        End Set
    End Property
    Public Property Address2() As String
        Get
            Return GetPropertyValue(Of String)(NameOf(Address2))
        End Get
        Set(ByVal value As String)
            SetPropertyValue(Of String)(NameOf(Address2), value)
        End Set
    End Property
End Class

The sample Contact class contains five properties: Name, IsMarried, SpouseName, Address1, Address2.

To ensure that the SpouseName Property Editor is only displayed when a contact is married, add the following AppearanceAttribute attribute. The IsMarried property should be decorated by the ImmediatePostDataAttribute attribute to ensure that the SpouseName Property Editor is immediately hidden when a user changes the IsMarried value.

C#

using DevExpress.ExpressApp.ConditionalAppearance;
using DevExpress.ExpressApp.Editors;
//...
[ImmediatePostData]
public bool IsMarried {
    // ...
}
[Appearance("Single", Visibility = ViewItemVisibility.Hide, Criteria = "!IsMarried", Context="DetailView")]
public string SpouseName {
    // ...
}

VB.NET

Imports DevExpress.ExpressApp.ConditionalAppearance
Imports DevExpress.ExpressApp.Editors
'...
<ImmediatePostData> _
Public ReadOnly Property IsMarried() As Boolean
    ' ...
End Property
<Appearance("Single", Visibility := ViewItemVisibility.Hide, Criteria := "!IsMarried", Context := "DetailView")> _
Public ReadOnly Property SpouseName() As String
    ' ...
End Property

The appearance rule, declared by the following attribute, ensures that the Address2 Property Editor is enabled only if the Address1 field is filled. Otherwise, the Address2 Property Editor should is disabled.

C#

[ImmediatePostData]
public string Address1 {
    // ...
}
[Appearance("AddressOneIsEmpty", Enabled = false, Criteria = "IsNullOrEmpty(Address1)", Context="DetailView")]
public string Address2 {
    // ...
}

VB.NET

<ImmediatePostData> _
Public Property Address1() As String
    ' ...
End Property
<Appearance("AddressOneIsEmpty", Enabled := False, Criteria := "IsNullOrEmpty(Address1)", Context := "DetailView")> _
Public Property Address2() As String
    ' ...
End Property