DashboardControl.CustomParameters Event

Occurs before data is loaded from the data store and allows you to customize dashboard parameters that are used for data processing.

Namespace: DevExpress.DashboardWpf

Assembly: DevExpress.Dashboard.v19.1.Wpf.dll

Declaration

C#

public event CustomParametersEventHandler CustomParameters

VB.NET

Public Event CustomParameters As CustomParametersEventHandler

Event Data

The CustomParameters event's data class is CustomParametersEventArgs. The following properties provide information specific to this event:

Property	Description
Parameters	Gets or sets dashboard parameters.

Remarks

The CustomParameters event provides access to a collection of dashboard parameters (CustomParametersEventArgs.Parameters) and allows you to change actual parameter values, parameter settings or even add new parameters. Note that parameter values specified in the CustomParameters event handler are used only for data processing and are not displayed in the Dashboard Parameters dialog.

Example

This example shows how to override an initial or user-defined dashboard parameter value by changing it in the DashboardControl.CustomParameters event handler. The effective parameter value is hidden from the end-user, and if you set the Visible property to false, the parameter itself will also be hidden.

To accomplish this task, a parameter named parameterState is added to the dashboard. It has a default value and a list of values to show it in a look-up editor. A Dashboard Parameters dialog displays the values and allows the end-user to select a parameter value in the list. However, by handling the DashboardControl.CustomParameters event, we can validate the parameter value and ignore the value provided by the end-user. To accomplish this, source data is filtered using a parameterState parameter.The value of this parameter is changed at runtime by handling the DashboardControl.CustomParameters event which is raised before the dashboard sends a query to a database. Thus, only the value passed in the DashboardControl.CustomParameters event is in effect.

Note

The complete sample project WPF Dashboard - How to Manage Dashboard Parameters in Code is available in the DevExpress Examples repository on GitHub.

C#

using System;
using DevExpress.Mvvm.DataAnnotations;
using DevExpress.Mvvm;
using DevExpress.Mvvm.POCO;
using System.Linq;
using DevExpress.DashboardCommon;
using System.Collections.Generic;

namespace WPF_Dashboard_CustomParameters.ViewModels
{
    [POCOViewModel]
    public class MyViewModel
    {
        protected MyViewModel() {
            //Dashboard = new SampleDashboard(); 
            Dashboard dashboard = new Dashboard();
            dashboard.LoadFromXml("Data\\SampleDashboard.xml");
            AddParameter(dashboard);
            ModifyFilter(dashboard);
            Dashboard = dashboard;
        }
        public virtual DevExpress.DashboardCommon.Dashboard Dashboard { get; set; }
        private void ModifyFilter(Dashboard dashboard)
        {
            dashboard.DataSources[0].Filter = "[State] In (?parameterState)";
        }
        private void AddParameter(Dashboard dashboard)
        {
            DashboardParameter myDashboardParameter = new DashboardParameter();
            StaticListLookUpSettings staticListLookUpSettings1 = new StaticListLookUpSettings();
            myDashboardParameter.AllowMultiselect = true;
            // Parameter values displayed in the look-up editor.
            staticListLookUpSettings1.Values = new string[] { "Alabama", "Ohio", "Utah" };
            myDashboardParameter.LookUpSettings = staticListLookUpSettings1;
            myDashboardParameter.Name = "parameterState";
            myDashboardParameter.Type = typeof(string);
            // Default parameter value.
            myDashboardParameter.Value = new List<string> { "Ohio", "Utah" };
            dashboard.Parameters.Add(myDashboardParameter);
        }
        public void OnCustomParameters(DevExpress.DashboardCommon.CustomParametersEventArgs e)
        {
            var customParameter = e.Parameters.FirstOrDefault(p => p.Name == "parameterState");
            if (customParameter != null)
            {
                // Actual value used when retrieving data from the data source.
                customParameter.Value = "Nevada";
            }
        }
    }
}

VB.NET

Imports System
Imports DevExpress.Mvvm.DataAnnotations
Imports DevExpress.Mvvm
Imports DevExpress.Mvvm.POCO
Imports System.Linq
Imports DevExpress.DashboardCommon
Imports System.Collections.Generic

Namespace WPF_Dashboard_CustomParameters.ViewModels
    <POCOViewModel> _
    Public Class MyViewModel
        Protected Sub New()
            'Dashboard = new SampleDashboard(); 

            Dim dashboard_Renamed As New Dashboard()
            dashboard_Renamed.LoadFromXml("Data\SampleDashboard.xml")
            AddParameter(dashboard_Renamed)
            ModifyFilter(dashboard_Renamed)
            Dashboard = dashboard_Renamed
        End Sub
        Public Overridable Property Dashboard() As DevExpress.DashboardCommon.Dashboard
        Private Sub ModifyFilter(ByVal dashboard As Dashboard)
            dashboard.DataSources(0).Filter = "[State] In (?parameterState)"
        End Sub
        Private Sub AddParameter(ByVal dashboard As Dashboard)
            Dim myDashboardParameter As New DashboardParameter()
            Dim staticListLookUpSettings1 As New StaticListLookUpSettings()
            myDashboardParameter.AllowMultiselect = True
            ' Parameter values displayed in the look-up editor.
            staticListLookUpSettings1.Values = New String() { "Alabama", "Ohio", "Utah" }
            myDashboardParameter.LookUpSettings = staticListLookUpSettings1
            myDashboardParameter.Name = "parameterState"
            myDashboardParameter.Type = GetType(String)
            ' Default parameter value.
            myDashboardParameter.Value = New List(Of String) From {"Ohio", "Utah"}
            dashboard.Parameters.Add(myDashboardParameter)
        End Sub
        Public Sub OnCustomParameters(ByVal e As DevExpress.DashboardCommon.CustomParametersEventArgs)
            Dim customParameter = e.Parameters.FirstOrDefault(Function(p) p.Name = "parameterState")
            If customParameter IsNot Nothing Then
                ' Actual value used when retrieving data from the data source.
                customParameter.Value = "Nevada"
            End If
        End Sub
    End Class
End Namespace