如何在C＃中检查文件夹中已上传的文件或图像

Question

I have been created student details using asp.net and c#.

I added image field recently, when i edit the details, and edit some of the fields without image filed(edit if necessary), and submit..It shows "please upload your image" in alert.

So i need to check if image is empty in images folder and also in file upload.

Here is my code:

code-behind:

protected void btnsub_Click(object sender, EventArgs e)
        {
            SqlConnection con = Connection.DBconnection();
            if (Textid.Text.Trim().Length > 0)
            {
                SqlCommand com = new SqlCommand("StoredProcedure3", con);
                com.CommandType = CommandType.StoredProcedure;
                com.Parameters.AddWithValue("@id", Textid.Text.Trim());
                com.Parameters.AddWithValue("@Name", Textusername.Text.Trim());
                com.Parameters.AddWithValue("@Class", Textclass.Text.Trim());
                com.Parameters.AddWithValue("@Section", Textsection.Text.Trim());
                com.Parameters.AddWithValue("@Address", Textaddress.Text.Trim());
                try
                {
                    string filename = string.Empty;
                    if (fileupload.PostedFile.FileName.Length > 0)
                    {
                        filename = Path.GetFileName(fileupload.PostedFile.FileName);
                        fileupload.SaveAs(Server.MapPath("~/Images/" + filename));
                    }
                    com.Parameters.AddWithValue("@Image",(filename.Length>0)? "Images/" + filename:string.Empty);
                    com.ExecuteNonQuery();                    
                }
                catch (Exception ex)
                {
                    btnsub.Text = ex.Message;
                }
                Response.Redirect("studententry.aspx");
            }
            else
            {
                SqlCommand com = new SqlCommand("StoredProcedure1", con);
                com.CommandType = CommandType.StoredProcedure;
                com.Parameters.AddWithValue("@Name", Textusername.Text.Trim());
                com.Parameters.AddWithValue("@Class", Textclass.Text.Trim());
                com.Parameters.AddWithValue("@Section", Textsection.Text.Trim());
                com.Parameters.AddWithValue("@Address", Textaddress.Text.Trim());
                try
                {
                    string filename = string.Empty;
                    if (fileupload.PostedFile.FileName.Length > 1)
                    {
                        filename = Path.GetFileName(fileupload.PostedFile.FileName);
                        fileupload.SaveAs(Server.MapPath("~/Images/" + filename));
                    }
                    com.Parameters.AddWithValue("@Image",(filename.Length>0)? "Images/" + filename:string.Empty);
                    com.ExecuteNonQuery();                    
                }
                catch (Exception ex)
                {
                    btnsub.Text = ex.Message;
                }
                Response.Redirect("studententry.aspx");
            }
        }
        protected void btnrst_Click(object sender, EventArgs e)
        {
            Textid.Text = string.Empty;
            Textusername.Text = string.Empty;
            Textclass.Text = string.Empty;
            Textsection.Text = string.Empty;
            Textaddress.Text = string.Empty;
        }
        protected void GridView1_RowCommand(object sender, GridViewCommandEventArgs e)
        {
            SqlConnection con = Connection.DBconnection();

            if (e.CommandName == "EditRow")
            {

                GridViewRow gr = (GridViewRow)((Button)e.CommandSource).NamingContainer;
                int index = gr.RowIndex; 
                hiddenfield.Value = index.ToString(); 
                Textid.Text = gr.Cells[0].Text;
                Textusername.Text = gr.Cells[1].Text;
                Textclass.Text = gr.Cells[2].Text;
                Textsection.Text = gr.Cells[3].Text;
                Textaddress.Text = gr.Cells[4].Text;
                Image1.ImageUrl = ((System.Web.UI.WebControls.Image)gr.Cells[5].Controls[0]).ImageUrl;               
            }
            else if (e.CommandName == "Deleterow")
            {
                SqlCommand com = new SqlCommand("StoredProcedure4", con);
                com.CommandType = CommandType.StoredProcedure;
                com.Parameters.AddWithValue("@ID", Convert.ToInt32(e.CommandArgument));
                var id = Int32.Parse(e.CommandArgument.ToString());                
                com.ExecuteNonQuery();
                Response.Redirect("studententry.aspx");
            }
        }
        protected void GridView1_SelectedIndexChanged(Object sender, EventArgs e)
        {
            int index = GridView1.SelectedIndex;
            hiddenfield.Value = index.ToString();
        }

aspx:

<asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server">

    <center><div><h4>Student Registration</h4></div></center>
<div class="tblalign">
    <table style="width: 100%;">
    <tr>
    <td><asp:HiddenField ID="hiddenfield" runat="server" /> 
    <asp:TextBox ID="Textid" runat="server" Visible="false"></asp:TextBox>
    </td>

    </tr>
        <tr>
            <td>
                <asp:Label ID="Label1" runat="server" Text="Name"></asp:Label>

            </td>
            <td>
                &nbsp;
            </td>
            <td>
                <asp:TextBox ID="Textusername" runat="server"></asp:TextBox>

            </td>
        </tr>
        <tr>
            <td>
                <asp:Label ID="Label2" runat="server" Text="Class"></asp:Label>

            </td>
            <td>
                &nbsp;
            </td>
            <td>
                <asp:TextBox ID="Textclass" runat="server"></asp:TextBox>

            </td>
        </tr>
        <tr>
            <td>
                <asp:Label ID="Label3" runat="server" Text="Section"></asp:Label>

            </td>
            <td>
                &nbsp;
            </td>
            <td>
                <asp:TextBox ID="Textsection" runat="server"></asp:TextBox>
            </td>
        </tr>
        <tr>
        <td>
            <asp:Label ID="Label5" runat="server" Text="Address"></asp:Label>
        </td>

        <td>
            &nbsp;
        </td>
        <td>
            <asp:TextBox ID="Textaddress" runat="server"></asp:TextBox>
        </td>
        </tr>
        <tr>
            <td>
            <asp:Label ID="Label4" runat="server" Text="Image"></asp:Label>
            </td>
            <td>
            &nbsp;
        </td>
        <td>
            <asp:Image ID="Image1" runat="server" ControlStyle-Width="50" ControlStyle-Height = "50"  />

        </td>
        <td>
        <asp:FileUpload ID="fileupload" runat="server" />  
         </td>
        </tr>
        <tr>
        <td>
            <asp:Button ID="btnsub" runat="server" Text="Submit" OnClick="btnsub_Click" OnClientClick="return register();" />
            <asp:Button ID="btnrst" runat="server" Text="Reset" OnClick="btnrst_Click" />
        </td>
        <td>
        </td>            
        <td>            
        </td>
    </tr>

</table></div>
<br />
<br />
<center><div><h4>Student Records</h4></div></center><br /> <br />
    <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" 
        DataKeyNames="ID" DataSourceID="SqlDataSource1" 
        OnRowCommand="GridView1_RowCommand" 
        EnablePersistedSelection="True" BackColor="White" 
        OnSelectedIndexChanged="GridView1_SelectedIndexChanged">
        <Columns>
            <asp:BoundField DataField="ID" HeaderText="ID" InsertVisible="False" 
                ReadOnly="True" SortExpression="ID" />
            <asp:BoundField DataField="Name" HeaderText="Name" SortExpression="Name" />
            <asp:BoundField DataField="Class" HeaderText="Class" SortExpression="Class" />
            <asp:BoundField DataField="Section" HeaderText="Section" 
                SortExpression="Section" />
            <asp:BoundField DataField="Address" HeaderText="Address" 
                SortExpression="Address" />
                <asp:ImageField DataImageUrlField="Image" HeaderText="Image" ControlStyle-Width="50" ControlStyle-Height = "50">                
                </asp:ImageField> 
            <asp:TemplateField HeaderText="Edit">
               <ItemTemplate>
                 <asp:Button runat="server" ID="btnedit" Text="Edit" CommandName="EditRow"></asp:Button>                    
               </ItemTemplate>
                <ControlStyle BorderColor="#CCFF66" />
          </asp:TemplateField>
          <asp:TemplateField HeaderText="Delete">
          <ItemTemplate>
                 <asp:Button runat="server" ID="btndelete" Text="Delete" CommandArgument='<%# Eval("Id") %>' CommandName="Deleterow"></asp:Button>                    
               </ItemTemplate>
          </asp:TemplateField>            
        </Columns>
        <SelectedRowStyle BackColor="#FF66FF" />
    </asp:GridView>
        <asp:SqlDataSource ID="SqlDataSource1" runat="server" 
        ConnectionString="<%$ ConnectionStrings:ConnectionString %>" 
        SelectCommand="StoredProcedure2"          
        SelectCommandType="StoredProcedure">
            <DeleteParameters>
                <asp:Parameter Name="ID" />
                <asp:Parameter Name="Name" />
                <asp:Parameter Name="Class" />
                <asp:Parameter Name="Section" />
                <asp:Parameter Name="Image" />
            </DeleteParameters>
            <UpdateParameters>
                <asp:Parameter Name="ID" />
                <asp:Parameter Name="Name" />
                <asp:Parameter Name="Class" />
                <asp:Parameter Name="Section" />
                <asp:Parameter Name="Image" />
            </UpdateParameters>
    </asp:SqlDataSource>
</asp:Content>

OUTPUT

I think in editrow command, i need to check the condition. Actually i'm new to .net.

So can anyone help me to fix this problem.

Any help would be highly appreciated.

Thanks,

Answer 1

To check for specific files use File.Exists(path) , which will return a boolean value indicating whether the file at path exists.

System.IO.File.Exists(path)

As your code is synchronous, it is possible to check whether the image is loaded immediately after uploading an image to the folder. For example:

try
  {
     string filename = string.Empty;
     if (fileupload.PostedFile.FileName.Length > 0)
        {
           filename = Path.GetFileName(fileupload.PostedFile.FileName);
           fileupload.SaveAs(Server.MapPath("~/Images/" + filename));
        }     
     string imgAddress = Path.GetFileName(fileupload.PostedFile.FileName);   
     //check whether your image is created:
     bool isExist=System.IO.File.Exists(imgAddress);
     com.Parameters.AddWithValue("@Image",(filename.Length>0)? "Images/" + filename:string.Empty);
     com.ExecuteNonQuery();                    
  }
catch (Exception ex)
{
   btnsub.Text = ex.Message;
}

Answer 2

filename = Path.GetFileName(fileupload.PostedFile.FileName);
var fullPath="~/Images/" + filename;


if (System.IO.File.Exists(Server.MapPath(fullPath)))
{
    // file exist
}
else
{
   // file not exist
}