How to: Disable and Hide Property Editors Based on a Business Rule

• Feb 24, 2022
• 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.

Tip

A complete sample project is available in the DevExpress Code Examples database at https://supportcenter.devexpress.com/ticket/details/e1672/how-to-disable-property-editors-based-on-a-business-rule.

Note

See more examples on how to use the Conditional Appearance in the Feature Center demo installed with XAF, or refer to the Feature Center demo online.

 

Create a new XAF Solution using the DevExpress v19.1 XAF Solution Wizard template. Add the Conditional Appearance module to the module and Mobile module project. To do this, invoke the Module Designer for the module (Mobile module) project and drag the ConditionalAppearanceModule (ConditionalAppearanceMobileModule) 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#

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

VB.NET

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)("Name")
        End Get
        Set(ByVal value As String)
            SetPropertyValue(Of String)("Name", value)
        End Set
    End Property
    Public Property IsMarried() As Boolean
        Get
            Return GetPropertyValue(Of Boolean)("IsMarried")
        End Get
        Set(ByVal value As Boolean)
            SetPropertyValue(Of Boolean)("IsMarried", value)
        End Set
    End Property
    Public Property SpouseName() As String
        Get
            Return GetPropertyValue(Of String)("SpouseName")
        End Get
        Set(ByVal value As String)
            SetPropertyValue(Of String)("SpouseName", value)
        End Set
    End Property
    Public Property Address1() As String
        Get
            Return GetPropertyValue(Of String)("Address1")
        End Get
        Set(ByVal value As String)
            SetPropertyValue(Of String)("Address1", value)
        End Set
    End Property
    Public Property Address2() As String
        Get
            Return GetPropertyValue(Of String)("Address2")
        End Get
        Set(ByVal value As String)
            SetPropertyValue(Of String)("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