Passing Multiple Parameters Between Forms

[Erlkoenig]

I have been trying to figure out, albeit unsuccessfully, the magic trick for passing multiple parameters between Forms.

The first form (frmReportLauncher) is used to select which report (of 9) to generate, and the second (frmReportBrowser) generates and displays the appropriate (unfortunately, Crystal) report in a viewer named crvReportViewer. Unless someone has a better idea, I am attempting to pass the appropriate DataSource, report Query (SQL), .rpt name, and a string to display in the report header. Right now I'm injecting the parameters into a function on the second Form to produce the report.

I've looked at countless posts related to passing parameters between forms. Most of these discuss passing a single parameter, which is fairly easy to do; I already do this elsewhere in my application. A handful discuss passing more than one parameter, but pretty much keep it to two. I figured expanding the scale would work, but no joy. I've tried both a public property approach and a constructor overload approach, but neither worked. I'm hoping someone could give (or point to) an example I can follow to make things work because at this point I have no idea how to make it happen.

TBH, I would rather use FastReports (OpenSource), but unfortunately it doesn't want to work for me either and all examples are C#, which I don't know at all. Using Crystal is a last-resort thing and my headaches are exacerbated by its not working with VS2026; it works with VS2022 though...

[wes4dbt]

Whether it's one or three the method is the same. If you use the constructor method,

Public Class Form2

    Private var1 As String
    Private var2 As String
    Private var3 As String

    Public Sub New(param1 As String, param2 As String, param3 As String)
        var1 = param1
        var2 = param2
        var3 = param3


        ' This call is required by the designer.
        InitializeComponent()

        ' Add any initialization after the InitializeComponent() call.

    End Sub

Use the appropriate data types, this example just uses strings.

[Erlkoenig]

Whether it's one or three the method is the same. If you use the constructor method,

Public Class Form2

Thanks. I figured that it's a case of scaling up. But I'm also going to assume "Form2" would really be the name declared in the code for the form containing the Crystal object; in my case, frmReportBrowser...

[dday9]

You could pass a class or an argument array if need be. For example, with a class:

Public Class ReportParameters
    Public Property Parameter1 As String
    Public Property Parameter2 As String
    Public Property Parameter3 As String
    ' etc...
End Class

Public Class frmReportBrowser

    Public Sub New(parameters As ReportParameters)
        InitializeComponent()

        ' do something...
    End Sub

End Class

Public Class MainForm

    Public Sub ButtonOpenReport_Click(sender As Object, e As EventArgs) Handles ButtonOpenReport.Click
        Dim parameters As New ReportParameters() With {
            .Parameter1 = "Foo",
            .Parameter2 = "Bar",
            .Parameter3 = "FooBar",
        }
        Using reportBrowser As New frmReportBrowser(parameters)
            reportBrowser.ShowDialog()
        End Using
    End Sub

End Class

Or with the argument array:

Public Class frmReportBrowser

    Public Sub New(args As String())
        InitializeComponent()

        _args = args
        If (_args Is Nothing) Then
            _args = {}
        End If

        Dim parameter1 As String = _args.FirstOrDefault()
        Dim parameter2 As String = _args.Skip(1).FirstOrDefault()
        Dim parameter3 As String = _args.Skip(2).FirstOrDefault()
        ' do something...
    End Sub

End Class

Public Class MainForm

    Public Sub ButtonOpenReport_Click(sender As Object, e As EventArgs) Handles ButtonOpenReport.Click
        Using reportBrowser As New frmReportBrowser(parameters)
            reportBrowser.ShowDialog("Foo", "Bar", "FooBar")
        End Using
    End Sub

End Class

The class option would provide you with scale while keeping strongly typed objects whereas the argument array will provide you scale but you'd be responsible with handling it properly.