AttachmentSelector Web Control - ASP.NET

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Features¶

Screen Shot of the AttachmentSelector Control

• FileName and URL properties which are read/write.
• A UrlMaxLength property, which gets or sets the MaxLength property of the URL textbox.
• A RequiredField property, which is used for validation.
• An AllowUrlAndDocument property, which is also used for validation. If False and the user specified both a URL and a file to upload, the IsValid property returns False.
• If the user tries to upload a file, the file extension is validated against the AllowedFileExtensions setting in the web.config file.
• An IsValid property, which is calculated based on other property settings.
• A ReasonInvalid property, which provides an explanation for why IsValid is False.
• An Attachment property, which is read-only, and returns the URL or FileName (whichever is specified).
• A VirtualUploadPath property, which sets the target path of the uploaded file
• An Upload method, which uploads the file to the VirtualUploadPath folder.
• An UploadTo method, which accepts a server virtual path to upload the file to. (If no upload file is specified, then this method does nothing.)
• CssClassLabel and CssClassData properties which set the CssClass property of the various child controls.
• An AlternateLink property, which accepts literal HTML code to be used in place of the document hyperlink for an uploaded file. (This doesn't display when the user specifies a URL — only an uploaded file.)
  

Screen Shot of the AttachmentSelector Control using the AlternateLink feature

Sample Implementation¶

ASPX Markup¶

<asp:CustomValidator runat="server" ID="uxAttachmentValidator"
    SetFocusOnError="true" ValidationGroup="MainValidationGroup"
    EnableClientScript="false"
    OnServerValidate="uxAttachmentValidator_Validate"
    ErrorMessage="ERROR"
    >
    
    <asp:Image ID="Image6" runat="server" 
        ImageUrl="~/images/Exclamation.PNG" />

    </asp:CustomValidator>

...

<abc:AttachmentSelector runat="server" ID="uxAttachmentSelector" 
    AllowUrlAndDocument="false" RequiredField="false"
    />

Code-Behind¶

• When displaying a record, set the File, URL, or both properties of the AttachmentSelector.
• After saving a record, call the AttachmentSelector.UploadTo(serverPath) method.
  

VB.NET¶

Protected Sub uxAttachmentValidator_Validate(ByVal sender As Object, ByVal e As _
ServerValidateEventArgs)

    Dim uxValidator As CustomValidator = CType(sender, CustomValidator)
    Dim selectorName As String = uxValidator.ID.Replace("Validator", "Selector")
    Dim c As Control = uxValidator.Parent.FindControl(selectorName)
    Dim uxAttachmentSelector As AttachmentSelector = CType(c, AttachmentSelector)

    e.IsValid = uxAttachmentSelector.IsValid
    uxValidator.ErrorMessage = uxAttachmentSelector.ReasonInvalid

End Sub

C#¶

TODO

Source Code¶

ASPX Markup¶

<%@ Control Language="VB" AutoEventWireup="false" CodeFile="AttachmentSelector.ascx.vb"
    Inherits="AttachmentSelector" %>

<asp:HiddenField runat="server" ID="uxFileNameField" />
<asp:HiddenField runat="server" ID="uxUploadPathField" />

<asp:Table runat="server" ID="uxDocumentTable" Width="100%">

    <%-- Document Link, Literal Control, and Delete Checkbox --%>
    <asp:TableRow>
        <asp:TableCell VerticalAlign="middle" HorizontalAlign="right" CssClass="fieldLabel" Font-Size="8pt"
                Width="7em" ID="uxDocumentCell">
            Link:
            </asp:TableCell>
        <asp:TableCell VerticalAlign="middle" HorizontalAlign="left" ColumnSpan="2" >
        
            <asp:HyperLink runat="server" ID="uxDocumentHyperLink" Target="_blank" CssClass="fieldLabel" ForeColor="blue" />
            <asp:Literal runat="server" ID="uxAlternateLinkLiteral" Text="" />
            &nbsp;
            <asp:CheckBox runat="server" ID="uxDeleteCheckBox" Checked="false" Text="No attachment"
                Visible="false" CssClass="fieldLabel" />
        
                
        </asp:TableCell>
    </asp:TableRow>
    
    <%-- File Upload --%>
    <asp:TableRow>
    
        <asp:TableCell VerticalAlign="middle" HorizontalAlign="right" CssClass="fieldLabel" Font-Size="8pt"
            ID="uxUploadCell" Text="Replace with:" />
            
        <asp:TableCell VerticalAlign="middle" HorizontalAlign="left">
        
            <asp:FileUpload runat="server" ID="uxFileUpload" Width="98%" CssClass="fieldData" />
            
        </asp:TableCell>
    </asp:TableRow>
    
    <%-- URL --%>
    <asp:TableRow>
        <asp:TableCell VerticalAlign="middle" HorizontalAlign="right" CssClass="fieldLabel" Font-Size="8pt"
            ID="uxUrlCell" Text="URL:" />
            
        <asp:TableCell VerticalAlign="middle" HorizontalAlign="left">
        
            <asp:TextBox runat="server" ID="uxUrlTextBox" Width="98%" CssClass="fieldData" />
            
        </asp:TableCell>
    </asp:TableRow>
    
</asp:Table>

Code-Behind¶

VB.NET¶

<%@ Control Language="VB" AutoEventWireup="false" CodeFile="AttachmentSelector.ascx.vb"  
    Inherits="AttachmentSelector"   
    %>

Imports System.IO

Partial Class AttachmentSelector

    Inherits System.Web.UI.UserControl

    Private _reasonInvalid As String
    Private _allowUrlAndDoc As Boolean
    Private _requiredField As Boolean
    Private _cssClassLabels As String
    Private _cssClassFields As String
    Private _labels() As String
    Private _fields() As String

    Public Sub UserControl_PreRender(ByVal sender As Object, ByVal e As EventArgs) Handles Me.PreRender

        'uxDebuggingLabel.Visible = System.Diagnostics.Debugger.IsAttached

        For Each s As String In _labels
            Dim ctl As WebControl = Me.FindControl(s)
            If ctl IsNot Nothing Then
                ctl.CssClass = _cssClassLabels
            End If
        Next

        For Each s As String In _fields
            Dim ctl As WebControl = Me.FindControl(s)
            If ctl IsNot Nothing Then
                ctl.CssClass = _cssClassFields
            End If
        Next

        DisplayHyperLink()

    End Sub
    Public Sub New()

        _reasonInvalid = ""
        _allowUrlAndDoc = False
        _requiredField = False
        _labels = New String() {"uxDebuggingLabel", "uxDocumentCell", "uxDocumentHyperLink", _
                                "uxDeleteCheckBox", "uxUrlCell", "uxUploadCell"}
        _fields = New String() {"uxUrlTextBox", "uxFileUpload"}

    End Sub

    Public Property AllowUrlAndDocument() As Boolean
        Get
            Return _allowUrlAndDoc
        End Get
        Set(ByVal value As Boolean)
            _allowUrlAndDoc = value
        End Set
    End Property

    ''' <summary>
    ''' If specified, returns the URL; otherwise returns the FileName specified.
    ''' </summary>
    Public ReadOnly Property Attachment() As String
        Get
            Dim result As String = Me.FileName
            If Me.URL.Length > 0 Then
                result = Me.URL
            End If
            Return result
        End Get
    End Property

    Public Property CssClassLabel() As String
        Get
            Return _cssClassLabels
        End Get
        Set(ByVal value As String)
            _cssClassLabels = value
        End Set
    End Property

    Public Property CssClassData() As String
        Get
            Return _cssClassFields
        End Get
        Set(ByVal value As String)
            _cssClassFields = value
        End Set
    End Property

    ''' <summary>
    ''' File name WITHOUT path
    ''' </summary>
    Public Property FileName() As String
        Get

            Dim result As String = ""

            If Me.URL.Length = 0 And Not uxDeleteCheckBox.Checked Then

                result = uxFileUpload.FileName

                If result.Length = 0 Then

                    result = uxFileNameField.Value

                End If

            End If

            Return result

        End Get
        Set(ByVal value As String)
            uxFileNameField.Value = value
            DisplayHyperLink()
        End Set
    End Property

    Public ReadOnly Property IsValid() As Boolean
        Get

            Dim result As Boolean = False
            Dim validExtensions As String = ConfigurationManager.AppSettings("AllowedFileExtensions")
            _reasonInvalid = ""

            Dim itemsSpecified As Integer = 0

            If uxUrlTextBox.Text.Length > 0 Then
                itemsSpecified += 1
            End If

            If uxFileUpload.HasFile Then
                itemsSpecified += 1
            End If

            'result = (itemsSpecified <= 1)

            '-- Verify something was specified (?) ------------------------------------------------
            If _requiredField And itemsSpecified = 0 And uxFileNameField.Value.Length = 0 Then

                _reasonInvalid = "Either Document or URL must be specified."

            '-- Verify both weren't specified (?) -------------------------------------------------
            ElseIf itemsSpecified = 2 And Not _allowUrlAndDoc Then

                _reasonInvalid = "Cannot specify both a Document and a URL."


            '-- Verify that Valid Extensions are Configured ---------------------------------------
            ElseIf validExtensions Is Nothing Then

                _reasonInvalid = "No valid extensions for file uploads were found in the " & _
                                    "configuration file."

            '-- Validate File Extension for Uploaded File (?) -------------------------------------
            ElseIf uxFileUpload.HasFile Then

                Dim exts() As String = validExtensions.Split(New Char() {"|"c}, _
                                            StringSplitOptions.RemoveEmptyEntries)

                Dim myExt As String = Path.GetExtension(uxFileUpload.FileName).ToUpper()
                If myExt.Length > 0 Then
                    myExt = myExt.Substring(1)
                End If

                _reasonInvalid = "You are not allowed to upload files with an extension of '." & _
                                    myExt & "'"

                For Each ext As String In exts

                    If myExt = ext.ToUpper() Then
                        result = True
                        _reasonInvalid = ""
                    End If

                Next

            '-- Default Case ----------------------------------------------------------------------
            Else

                result = True

            End If

            Return result

        End Get
    End Property

    Public Property AlternateLink() As String
        Get
            Return uxAlternateLinkLiteral.Text
        End Get
        Set(ByVal value As String)
            uxAlternateLinkLiteral.Text = value
            DisplayHyperLink()
        End Set
    End Property

    ''' <remarks>IMPORTANT: Be sure to call the IsValid property before accessing the 
    '''     ReasonInvalid property!</remarks>
    Public ReadOnly Property ReasonInvalid() As String
        Get

            Return _reasonInvalid

        End Get
    End Property

    Public Property RequiredField() As Boolean
        Get
            Return _requiredField
        End Get
        Set(ByVal value As Boolean)
            _requiredField = value
            uxDeleteCheckBox.Visible = Not _requiredField
        End Set
    End Property

    Public Property VirtualUploadPath() As String
        Get
            Return uxUploadPathField.Value
        End Get
        Set(ByVal value As String)
            uxUploadPathField.Value = value
            DisplayHyperLink()
        End Set
    End Property

    Public Property URL() As String
        Get
            Dim result As String = ""
            If Not uxDeleteCheckBox.Checked Then
                result = uxUrlTextBox.Text
            End If
            Return result
        End Get
        Set(ByVal value As String)
            uxUrlTextBox.Text = value
            DisplayHyperLink()
        End Set
    End Property

    Public Property UrlMaxLength() As Integer
        Get
            Return uxUrlTextBox.MaxLength
        End Get
        Set(ByVal value As Integer)
            uxUrlTextBox.MaxLength = value
        End Set
    End Property

    Public Sub UploadTo(ByVal virtualPath As String)

        If uxFileUpload.HasFile AndAlso Me.IsValid And Not uxDeleteCheckBox.Checked Then

            Try

                Me.VirtualUploadPath = virtualPath

                Dim shortFileName As String = uxFileUpload.FileName
                Dim serverPath As String = Me.Page.Server.MapPath(virtualPath)

                If Not Directory.Exists(serverPath) Then
                    Directory.CreateDirectory(serverPath)
                End If

                Dim serverFile As String = Path.Combine(serverPath, shortFileName)

                uxFileUpload.SaveAs(serverFile)

            Catch ex As Exception

                Throw ex

            End Try

        End If

        DisplayHyperLink()

    End Sub
    ''' <summary>
    ''' Maps the VirtualUploadPath property to a physical path on the server, creates the folder  
    ''' (if necessary), and uploads the specified file to this folder.
    ''' </summary>
    Public Sub Upload()
        Me.UploadTo(Me.VirtualUploadPath)
    End Sub

    Private Sub DisplayHyperLink()

        If Not Me.IsValid Then

            ' Do nothing

        ElseIf Me.URL.Length > 0 Then

            uxDocumentHyperLink.Visible = True
            uxDocumentHyperLink.Text = Me.URL
            uxDocumentHyperLink.NavigateUrl = Me.URL
            uxDeleteCheckBox.Visible = Not _requiredField
            uxAlternateLinkLiteral.Visible = False
            uxUploadCell.Text = "Upload:"

        ElseIf Me.FileName.Length > 0 Then

            uxDocumentHyperLink.Text = Me.FileName
            uxDocumentHyperLink.Visible = (uxAlternateLinkLiteral.Text.Length = 0)
            uxDocumentHyperLink.NavigateUrl = Path.Combine(Me.VirtualUploadPath, Me.FileName)
            uxDeleteCheckBox.Visible = Not _requiredField
            uxAlternateLinkLiteral.Visible = True
            uxUploadCell.Text = "Replace with:"

        Else

            uxDocumentHyperLink.Text = "(unspecified)"
            uxDocumentHyperLink.Visible = True
            uxDocumentHyperLink.NavigateUrl = ""
            uxDeleteCheckBox.Visible = False
            uxAlternateLinkLiteral.Visible = False
            uxUploadCell.Text = "Upload:"
            
            ' This is to prevent retaining the URL or FileName
            uxUrlTextBox.Text = ""
            uxFileNameField.Value = ""

        End If

        ' This is to prevent retaining the "No attachment" selection
        If Not uxDeleteCheckBox.Visible Then
            uxDeleteCheckBox.Checked = False
        End If

    End Sub

End Class

C#¶

<%@ Control Language="C#" AutoEventWireup="false" CodeFile="AttachmentSelector.ascx.cs"  
    Inherits="AttachmentSelector"   
    %>

TODO