<asp:TemplateField HeaderText="PDF" SortExpression="PDFUrl">
                
                <InsertItemTemplate>
                    <asp:FileUpload ID="FileUpload1" runat="server" />
                    <br />
                    <asp:CustomValidator ID="cusValPDF" runat="server" ErrorMessage="Select .PDF file." CssClass="ErrorMessage" />
                </InsertItemTemplate>
                <ItemTemplate>
                    <asp:Label ID="PDFLabel" runat="server" Text='<%# Item.PDFUrl %>' />
                </ItemTemplate>
            </asp:TemplateField>

<asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString=... InsertCommand="INSERT INTO [Review].... ([PDFUrl])..../>

<InsertParameters>
...
     <asp:Parameter Name="PDFUrl" Type="String" />
</InsertParameters>

<SelectParameters>
            <asp:QueryStringParameter Name="Id" QueryStringField="Id" Type="Int32" />
</SelectParameters>

<UpdateParameters>
...
            <asp:Parameter Name="PDFUrl" Type="String" />
</UpdateParameters>

protected void DetailsView1_ItemInserting(object sender, DetailsViewInsertEventArgs e)
    {
        e.Values["UpdateDateTime"] = DateTime.Now;
        
        FileUpload FileUpload1 = (FileUpload)DetailsView1.FindControl("FileUpload1");
        if (!FileUpload1.HasFile || !FileUpload1.FileName.ToLower().EndsWith(".pdf"))
        {
            CustomValidator cusValImage = (CustomValidator)DetailsView1.FindControl("cusValPDF");
            cusValImage.IsValid = false;
            e.Cancel = true;
        }
    }

protected void SqlDataSource1_Inserting(object sender, SqlDataSourceCommandEventArgs e)
    {
        int genreId = Convert.ToInt32(Request.QueryString.Get("GenreId"));
        
        Review filePDF = (Review)e.Entity;  // here I cannot access the e.Entity
        filePDF.GenreId= genreId;              // because I'm using SqlDataSource instead EntityDataSource
                                            

        FileUpload FileUpload1 = (FileUpload)DetailsView1.FindControl("FileUpload1");
        string virtualFolder = "~/PDF/";
        string physicalFolder = Server.MapPath(virtualFolder);
        string fileName = Guid.NewGuid().ToString();
        string extension = System.IO.Path.GetExtension(FileUpload1.FileName);
        FileUpload1.SaveAs(System.IO.Path.Combine(physicalFolder, fileName + extension));
        filePDF.PDFUrl= virtualFolder + fileName + extension;
    }

<asp:DetailsView ID="DetailsView1" runat="server">
                <Fields>
                    <asp:TemplateField HeaderText="PDF" SortExpression="PDFUrl">
                        <ItemTemplate>
                            <asp:HyperLink ID="HyperLink2" runat="server" NavigateUrl='<%# String.Format("../Uploads/{0}.pdf", Eval("Id").ToString()) %>' Text="View in Browser" Target="_blank"></asp:HyperLink>
                        </ItemTemplate>
                    </asp:TemplateField>
                </Fields>
            </asp:DetailsView>

Review filePDF = (Review)e.Entity;
          filePDF.GenreId= genreId;

protected void DetailsView1_ItemInserting(object sender, DetailsViewInsertEventArgs e)
    {
        e.Values["UpdateDateTime"] = DateTime.Now;
        
        // Insert book
        FileUpload FileUpload1 = (FileUpload)DetailsView1.FindControl("FileUpload1");
        string virtualFolder = "~/PDF/";
        string physicalFolder = Server.MapPath(virtualFolder);
        string fileName = Guid.NewGuid().ToString();
        string extension = System.IO.Path.GetExtension(FileUpload1.FileName);
        
        // Upload file:
        FileUpload1.SaveAs(System.IO.Path.Combine(physicalFolder, fileName + extension));

        //Assign url to db
        e.Values["PDFUrl"] = virtualFolder + fileName + extension;

        // Validate book's type
        if (!FileUpload1.HasFile || !FileUpload1.FileName.ToLower().EndsWith(".pdf"))
        {
            CustomValidator CustomValidator1 = (CustomValidator)DetailsView1.FindControl("CustomValidator1");
            CustomValidator1.IsValid = false;
            e.Cancel = true;
        }
    }