i have a asp fileupload control on my page. how to validate the selected file on client side.
validation rules:
1. file must be jpeg,png,bmp or gif.
2. file size must be within 25 kb and 2 mb.
please help.
thanks.
I Have Tried The Following Code to validate the extension
<asp:FileUpload ID="FileUpload2" runat="server"/>
<asp:CustomValidator ID="CustomValidator1" runat="server" ClientValidationFunction="ValidateFileUpload" ErrorMessage="Invalid file type. Only .gif, .jpg, .png, .bmp and .jpeg are allowed." ControlToValidate="FileUpload2" ValidationGroup="update"> </asp:CustomValidator>
<script language="javascript" type="text/javascript">
function ValidateFileUpload(Source, args) {
var fuData = document.getElementById('<%= fuData.ClientID %>');
var FileUploadPath = fuData.value;
if (FileUploadPath == '') {
// There is no file selected
args.IsValid = false;
}
else {
var Extension = FileUploadPath.substring(FileUploadPath.lastIndexOf('.') + 1).toLowerCase();
if (Extension == "jpg" || Extension == "jpeg" || Extension == "png" || Extension == "gif" || Extension == "bmp") {
args.IsValid = true; // Valid file type
}
else {
args.IsValid = false; // Not valid file type
}
}
}
</script>
You cannot determine the size of the file selected in the file input element via client side script. In order to determine the size of the file, one must have read access to the file. As you may imagine, allowing JavaScript to read files on your computer would be a "really bad idea."™
I often see this type of question, and believe that there is some confusion about what the file input element actually does. When the user selects a file, the file bytes aren't "loaded" into this element such that they are available for reading. Rather, the input specifies a reference to the file location so that the browser knows - when the form is posted - to encode the file and send it with the POST. This process is internal to the browser, and isn't exposed to the client in a manner that it can be leveraged by script.
If you need to do file size verification, you should do it on the server where you have access to the actual file bytes. If you are concerned with people "flooding" your site with very large files, you can specify the maximum allowable POST size by configuring your IIS instance.
You can try out ajax control tool kit. It has its own control for file upload. Its much more cool
In most browsers used nowadays, you can do client-side validation on file size:
https://stackoverflow.com/a/1832497/2705769
Related
I have registration form and button. OnClick - I call function on server side which make a validation of user's zip code at Database with Zipcodes. If validation passed successfully - user's data stored in Database (here I continue use server function). But if ZipCode does not match - I call Javascript function where I ask if user still wants to save his data to DB. and If yes - I save it using Ajax request. Problem is when I call Javascript function - firstly it should receive user's data on client side. But when reading data happens - I receive an error "Unable to get property 'value' of undefined or null reference". But user's data still exist at the form's fields. It seems that the data that read by the server from the form once - reset somewhere - and can not be read a second time on the client.
Here is my ASP Form
<body>
<form id="frmZipValidation" runat="server">
<div>
<asp:Label runat="server">Registration Form</asp:Label>
<asp:TextBox runat="server" ID="txtbxName"></asp:TextBox>
<asp:TextBox runat="server" ID="txtbxZipCode"></asp:TextBox>
<asp:DropDownList runat="server" ID="DDLCountry">
<asp:ListItem Text="Select country" Value="Select" Selected="True"></asp:ListItem>
<asp:ListItem Text="USA" Value="USA"></asp:ListItem>
<asp:ListItem Text="Canada" Value="Canada"></asp:ListItem>
</asp:DropDownList>
<asp:TextBox runat="server" ID="txtbxState"></asp:TextBox>
<asp:TextBox runat="server" ID="txtbxCity"></asp:TextBox>
<asp:Button runat="server" ID="btnSubmit" Text="Submit" OnClick="btnSubmit_Click"/>
</div>
</form>
</body>
Here is my Server Side
public partial class Default : System.Web.UI.Page
{
string Name;
string ZipCode;
string Country;
string State;
string City;
bool IsMatch;
Addresses dbAddresses = new Addresses();
User newUser;
protected void Page_Load(object sender, EventArgs e)
{
if (Request["Action"] != null && Request["Action"].Trim() != "")
{
if (Request["Action"] == "AddUser")
{
AddUser(Request["Name"], Request["ZipCode"], Request["Country"], Request["State"], Request["City"]);
}
}
}
private void AddUser(string UserName, string UserZip, string UserCountry, string UserState, string UserCity)
{
newUser = new User(UserName, UserZip, UserCountry, UserState, UserCity);
dbAddresses.Users.Add(newUser);
dbAddresses.SaveChanges();
}
protected void btnSubmit_Click(object sender, EventArgs e)
{
if (IsValid)
{
ZipCode = txtbxZipCode.Text;
Country = DDLCountry.Text;
State = txtbxState.Text;
City = txtbxCity.Text;
Name = txtbxName.Text;
IsMatch = false;
List<ZipCode> ZipC = (from z in dbAddresses.Zips
where z.Zip == ZipCode
select z).ToList();
//If ZipCode entered by client do not exists at Database return false
if (!ZipC.Any())
{
IsMatch = false;
}
else
{
for (int i = 0; i < ZipC.Count; i++)
{
if (ZipC[i].Country.ToString() == Country)
{
if (ZipC[i].State.ToString() == State)
{
if (ZipC[i].City.ToString() == City)
{
AddUser(Name, ZipCode, Country, State, City);
//Message to the user that all saved successfully
Page.ClientScript.RegisterClientScriptBlock(typeof(Page), "1", "<script>alert('Your data was saved successfully!');</script>");
IsMatch = true;
break;
}
else
{
IsMatch = false;
break;
}
}
else
{
IsMatch = false;
break;
}
}
else
{
IsMatch = false;
break;
}
}
}
//If user's data are not match, then go to JS client code where - If user wants in any case to save data - make it using AJAX request
if (!IsMatch)
{
string clientScript = "AjaxRequestSaveToDB();";
this.Page.ClientScript.RegisterStartupScript(this.GetType(), "MyClientScript", clientScript);
}
}
}
}
And here is Javascript:
function AjaxRequestSaveToDB()
{
var SaveData = confirm('Zip/Postal code doesn’t match region. Are you sure you want to save this data?');
if (SaveData)
{
var UserName = document.getElementById('txtbxName').value;
var UserZipCode = document.getElementById('txtbxZipCode').value;
var UserCountry = document.getElementById('DDLCountry').value;
var USerState = document.getElementById('txtbxState').value;
var UserCity = document.getElementById('txtbxCity').value;
SendDataToServer('AddUser', UserName, UserZipCode, UserCountry, USerState, UserCity);
alert("You data was saved successfully!");
}
else { alert('Not saved');
}
}
}
function SendDataToServer(RequestType, Name, ZipCode, Country, State, City)
{
var xmlHttp = getXmlHttp();
var Url = "Default.aspx?Action=" + escape(RequestType)
+ "&Name=" + escape(Name)
+ "&ZipCode=" + escape(ZipCode)
+ "&Country=" + escape(Country)
+ "&State=" + escape(State)
+ "&City=" + escape(City);
xmlHttp.open("GET", Url, true);
xmlHttp.send();
}
A short book about Client-Server Communications using "Custom" AJAX requests.
In ASP.net programming (almost) every time the client interacts with the server, the client sends all of its information to the server and then throws out its old content and replaces it with the response the client received from the server. So the problem you were running into is that your asp:button on the client machine was sending information to your .aspx page on the server and the server was interpreting the information, realizing something was wrong and telling the client it should ask the user for more information but throw out all the information that had been previously entered.
The best way that I have found to get around this problem is to use what I call "custom AJAX requests." Basically this means that we write a string of XML and send it to an ASP handler page which is set up to accept the XML string and do something with it. In my travels I have slimmed this down to basically 3 parts. The first is the user interface which contains all of the markup and CSS(and validation), the second is the JavaScript file that contains all of the data gathering and the actual AJAX request and lastly there is the ashx file that handles the request from the client.
So to start you will need to set up your user interface. Something along the lines of:
<body>
<form id="frmZipValidation" runat="server">
<div>
<div class="label">Registration Form<div>
<asp:TextBox ID="txtbxName" class="txtbxName" ClientIDMode="Static" runat="server"></asp:TextBox>
<asp:TextBox ID="txtbxZipCode" class="txtbxZipCode" ClientIDMode="Static" runat="server" ></asp:TextBox>
<asp:DropDownList ID="DDLCountry" class="DDLCountry" ClientIDMode="Static" runat="server" >
<asp:ListItem Text="Select country" Value="Select" Selected="True"></asp:ListItem>
<asp:ListItem Text="USA" Value="USA"></asp:ListItem>
<asp:ListItem Text="Canada" Value="Canada"></asp:ListItem>
</asp:DropDownList>
<asp:TextBox ID="txtbxState" class="txtbxState" ClientIDMode="Static" runat="server" ></asp:TextBox>
<asp:TextBox ID="txtbxCity" class="txtbxCity" ClientIDMode="Static" runat="server" ></asp:TextBox>
<input id="btnSubmit" class="btnSubmit" type="button" value="Save" onclick="SubmitForm()" />
</div>
</form>
</body>
Couple things to note with this:
The button to submit the form is NOT an ASP button but a HTML button.
All of the input controls are ASP controls but they have the ClientIDMode set to Static, this will only work in .NET 4.0 or higher.
We set the class to the same thing as the ID in case we aren't using .NET 4.0 or higher. Any CSS classes that you want to also add to the control can be added after the dummy ID class.(for my examples I'm assuming you are in .NET 4.0 but I can easily switch them to work without the ClientIDMode attribute if you need)
The second piece to the puzzle is the JavaScript. There are a couple ways that we can accomplish what we need. The first is by using vanilla JS without the help of any plugins or external libraries. This saves a very small amount of processing time, a marginal amount of loading time and can accomplish everything we ask of it. But, if we include an external library, JQuery, and plugin, JQuery Validation, then we can make our lives a whole heck of a lot easier during the programming phase by reducing the amount of code we have to write by a factor of about 10. And if we are really concerned about the load times then we can use the client cache to store the external libraries so that they only have to download them once. So whether or not you decide to use any external JavaScript libraries is up to what your project needs but since you are only concerned with validating that the zip code is not empty I will not use any JQuery but I just thought it would be worth mentioning because of how streamlined it makes the process.
Once you are ready to submit your form your first step will be to validate that the zipcode is valid. You can do this a couple ways depending on how in depth you want to get. The quickest check would just be to verify that the zip code text box is not empty when the button is clicked. So to do that we would just need to do:
function SubmitForm() { //This will be assigned as the click handler on your button in your HTML
if (document.getElementById('txtbxZipCode').value != null && document.getElementById('txtbxZipCode').value != '') {
Save('YourHandler', GetQueryString, GetXmlString, SuccessHandler, FailureHandler);
} else {
//Your user needs to know what went wrong...
}
}
So, down to the meat and potatoes of this whole situation. The AJAX request. I've come up with a reusable function that handles the entire AJAX request that looks like:
function Save(handlerName, GetQueryString, GetXmlString, SuccessHandler, FailureHandler) {
// Date.GetTime gets the number of milliseconds since 1 January 1970, so we divide by 1000 to get the seconds.
end = (new Date().getTime() / 1000) + 30;
//This variable is the actual AJAX request. This object works for IE8+ but if you want backwards compatability for earlier versions you will need a different object which I can dig up for you if you need.
var xmlhttp = new XMLHttpRequest();
//This is the function that fires everytime the status of the request changes.
xmlhttp.onreadystatechange = function () {
if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
//Get all the headers to determine whether or not the request was successful. This is a header you will need to add to the response manually.
var xx = xmlhttp.getResponseHeader("Success");
//the object xx will be a string that you designate. I chose to use True as the indicator that it was successful because it was intuitive.
var x1 = xx.trim();
if (x1 != undefined && x1 == 'True' && (new Date().getTime() / 1000) < end) {
//If the response was successful and the timeout hasn't elapsed then we get the XML from the response and call the success handler
var xmlResponse = xmlhttp.responseXML;
SuccessHandler(sender, xmlResponse);
} else if ((new Date().getTime() / 1000) < end) {
//If the response was not successful and the timeout hasn't elapsed then we get the XML from the response and call the failure handler
var xmlResponse = xmlhttp.responseXML;
FailureHandler(sender, xmlResponse);
} //If the request was successful
} //If the readystate is 4 and the status is 200
} //OnReadyStateChanged function
//This gets the query string to be added to the url
var varString = GetQueryString();
//Build XML string to send to the server
var xmlString = GetXmlString();
//Open the request using the handler name passed in and the querystring we got from the function passed in
xmlhttp.open("POST", "../RequestHandlers/" + handlerName + ".ashx" + varString, true);
//This tells the handler that the content of the request is XML
xmlhttp.setRequestHeader("Content-Type", "text/xml");
//Send the request using the XML we got from the other function passed in.
xmlhttp.send(xmlString);
}
This function has a built in timeout which makes it so that if the server takes more than 30 seconds to respond to a request then any response that the client receives is ignored. For my implementations this is combined with another function that displays something to the user to tell them that the website is working on their request and if the time out elapses it tells them that a time out occurred.
The second thing this function does is it assumes that all handlers will be in a folder next to the root of your website named RequestHandlers. I use this set up just to consolidate all of my handler files but you can really change where it is looking to wherever you want.
The function itself takes in a string and four function pointers. The string represents the name of the handler that will be waiting to interpret the request, the four function pointers all have very specific jobs.
The first function pointer is GetQueryString this represents a function you will have to write that will append any variables that you deem necessary to the end of the URL being posted back to. This site gives a pretty accurate explanation of what the query string should be used for. For me a common GetQueryString function looks something like:
function GetPaymentQueryString() {
var varString = '';
varString = "?CCPayment=True";
return varString;
}
The second function pointer, GetXMLString, is used to create the XML string(go figure...) that will be sent to the handler page that we are posting back to. This string will represent the bulk of the request. Everything that should not be shown to anyone snooping your requests should be sent as an XML string, if you are really paranoid you can send it as an encrypted XML string but that's not, strictly speaking, necessary. It all depends on what you are sending, if its complete credit card information then, yeah, maybe you would want to consider it, but if its first and last names then encrypting it would be overkill.
A common GetXMLString function might look like:
function GetPaymentXmlString() {
var xmlString = '';
xmlString = '<?xml version="1.0" encoding="UTF-8"?><Address><ZipCode>' + document.getElementById('txtbxZipCode').value + '</ZipCode></Address>';
return xmlString;
}
The important part of that function is to get your XML right. The first tag is pretty universal and should be fine to use in most situations and then after that its all just matching the tags up. I left out a lot of your fields to save space.
The last two function pointers are what you will want to call if everything goes as planned and if something fails respectively. The way that I normally handle successful requests is to hide the inputs as a whole(usually by putting them inside of their own div section) and displaying a confirmation message of some sort. Failed requests can be a bit trickier because you have to tell the user why they failed. The way that I do that is by having a dummy div section above everything else on the page with some sort of special CSS attached to it that makes the div stand out in some way and if the request fails then I send a string of text from the server with my best guess of why it failed and assign it to the be displayed in the div section. How you decide to display the results to the user is obviously all dictated by the project itself. Since what you do when it succeeds or fails is basically on a project by project basis I can't really give a good generic example of what you should do so for this part you are on your own.
Now that we have those pieces in place, the last piece to make is the handler.
Basically for all intents and purposes a handler is basically an ASPX webpage with nothing on it. So the HTML that makes up your handler pages, which have the extension .ashx, will look like:
<%# WebHandler Language="VB" CodeBehind="YourHandler.ashx.cs" Class="YourHandler" %>
And that's it. There should be no other markup in your actual .ashx file. Obviously the name of the handler will change depending on what you are doing.
The code behind when creating an ashx file by default will be a class that contains a single function named ProcessRequest. Basically you can treat this function as a sort of "request received" event. So in your case you would move the content of your btnSubmit_Click function to the ProcessRequest function in the ashx file. You can add any properties or other functions that you want but the ProcessRequest function must be present for the handler to work as far as I know.
One extra step that you will need to do is to get the information from the XML that was sent to your handler and also tell the response that you will be sending XML back to the client.
So to get the XML from the request you will need to do:
IO.StreamReader textReader = New IO.StreamReader(context.Request.InputStream);
context.Request.InputStream.Seek(0, IO.SeekOrigin.Begin);
textReader.DiscardBufferedData();
XDocument xml = XDocument.Load(textReader);
String zip = xml.Elements("Address").Elements("ZipCode").FirstOrDefault().Value;
In order to send XML back to the client you will need to add a couple headers to the response and you accomplish that by adding(I think this is the correct way to implement an interface in C# not positive on this point though):
class YourHandler : System.Web.IHttpHandler, System.Web.SessionState.IReadOnlySessionState
under your class definition and:
context.Response.ContentType = "text/xml";
context.Response.ContentEncoding = System.Text.Encoding.UTF8;
context.Response.Cache.SetCacheability(HttpCacheability.NoCache);
context.Response.Cache.SetAllowResponseInBrowserHistory(True);
to the beginning of your ProcessRequest function. Those six lines tell the client it will be receiving XML and not to cache any of the response which will ensure that your clients always see the most up-to-date content.
So. There it is. You should now have the framework to validate user input, create an AJAX request, send the request to a custom handler, accept XML from the client, write XML to the client and display the res-...I knew I forgot something...
What is the client supposed to do with the XML it gets from the server? throw it at the wall and see what sticks? No that won't work. You'll need a way to interpret the XML on the client side. Luckily the XMLHttpRequest object has been written to make this task a lot easier than it sounds.
You may have noticed that I set up my success and failure handlers to take a sender object and an XML object. The sender is really overkill and can be ignored(or removed) for this example to work fine. The XML object is what we are concerned with for now. Before we even get into the client side I must mention that you will have to go through the same process on the server side as you did on the client side and manually write your XML string including all the values you want the client to know about. For this example I'm going to assume you want to display a FriendlyMessage to the user. To write the response to the client you will do something like:
using (System.Xml.XmlTextWriter writer = new System.Xml.XmlTextWriter(context.Response.Output)) {
context.Response.AddHeader("Success", true);
System.Xml.XmlDocument doc = new System.Xml.XmlDocument();
doc.LoadXml("<?xml version='1.0' encoding='UTF-8'?><Response><FriendlyMessage>" + Message + "</FriendlyMessage></Response>");
doc.WriteTo(writer);
writer.Flush();
writer.Close();
}
On the client side to get the FriendlyMessage from the XML you will need to do:
xml.getElementsByTagName("FriendlyMessage")[0].childNodes[0].nodeValue
Now this line makes a few assumptions. Like, you may want to add some checks in to make sure xml.getElementsByTagName("FriendlyMessage") actually has children before trying to evaluate them. Those sorts of checks are up to your discretion.
This time I think I've actually covered all the steps. I hope my "little" guide helps you and I didn't bore you too much. I apologize for the length but its sort of a process so getting it right takes a few steps. Once you get the base line in place and working it really lends itself to any situation. This layout also makes your user experience much better than having them wait for full trips to the server each time.
I sincerely hope this helps you get your project done and that I haven't skipped a step or something equally as embarrassing...
I have excel file abc.xls and I renamed it as abc.doc using command prompt.
My requirement is: I want to upload a proper doc file, but there I can only check the MIME type of the file to upload file, this is not sufficient. I want to confirm before uploading the doc file, that it is a doc and not allow users to upload abc.doc file, because it is not a doc file its a excel file.
Because the OP wrote it in the comments:
You are on a wrong track here, Validation should always happen on the server side, you can add additional validation on the client side, but its not required. You have to do this for a simple reason:
Clients can always circumvent client-side Validation methods because the Client is fully under their control. So even if you implement your validation method to check if its a doc or excel document, a bad user can always just send you a post request with the validation disabled and you're getting a excel document or a virus etc.
This is a core webprogramming principle: Never trust input data, you can't validate on the client only!
Secondly your validation is done much mor easily on the server. So you should upload any file (check for file extensions & size) and then validate on the server!
You probably need an ActiveX Object to access the file content on the client system before uploading. Checking the byte array with javascript to find whether it's a real doc might prove interesting though :-)
EDIT :
function CheckWordDoc(filepath){
var fso, f, ts, s;
var ForReading = 1, ForWriting = 2, ForAppending = 8;
var TristateUseDefault = -2, TristateTrue = -1, TristateFalse = 0;
fso = new ActiveXObject("Scripting.FileSystemObject");
f = fso.getFile(filepath);
ts = f.OpenAsTextStream(ForReading, TristateUseDefault);
while (!ts.AtEndOfStream) {
s = ts.ReadLine();
if (s.indexOf("Word.Document.8") != -1) {
ts.Close( );
return true;
}
}
ts.Close( );
return false;
}
http://www.piclist.com/techref/language/asp/vbs/vbscript/jsmthopenastextstream.htm
http://msdn.microsoft.com/en-us/library/hwfw5c59%28v=vs.85%29.aspx
i am using file upload control in server side when iam trying to get the file it is showing no file present
<asp:FileUpload ID="upldDocument" runat="server" />
string fileExtension = System.IO.Path.GetExtension(upldDocument.FileName);
if (upldDocument.HasFile)
{
}
i am getting a empty string as file extension and upldDocument.HasFile is returning false even after selecting a file.
what could be the reason??
Based on the posted code, I can only offer a best guess. There's not enough code posted to be sure what the problem is, but here's my best guess:
If you're not already, you need to check the HasFile property.
See here for a full example:
Edit - added
Using HasFile AFTER the bad code won't help. You need to put the code to get the extention inside an if statement so that it only attempts to read the extension if there IS a file.
string fileExtension = "";
if (upldDocument.HasFile)
{
fileExtension = System.IO.Path.GetExtension(upldDocument.FileName);
}
else
{
//No file selected by user, which is why you can't get the extension.
// handle this eventuality here even if it means just returning from the function and not doing anything.
}
How are you checking the values? (in what event)
Did you set the enctype attribute of the form to "multipart/form-data" ?
in my current project I used a AsyncFileUpload control from AJAX Control Toolkits. After I got the async file upload part working, I needed to filter the file type so users can only upload image files. I found the following code off web and it worked well:
function uploadStarted(sender, args) {
var filename = args.get_fileName();
var filext = filename.substring(filename.lastIndexOf(".") + 1);
if (filext == "jpg" || filext == "jpeg" || filext == "gif" || filext == "bmp") {
return true;
}
else
{
// force uploading cancel
args.set_cancel(true);
// set reason of cancel
args.set_errorMessage("Invalid File Format Selected");
return false;
}
}
The problem is : I don't understand this javascript. What is the type of args parameter? Where are the methods such as "get_fileName()", "set_cancel()" defined? I went to the homepage of the AsyncFileUpload control but couldn't find any documentation regarding the "args".
Can someone help me out explaining this Javascript? Thanks
I think I can answer my own question
The first parameter identifies the object that fired the event, while the second provides information on the file being uploaded. In fact, it contains five useful properties accessed using the get_abc() syntax demonstrated above.
get_fileName() and get_path() both return the name of the file being uploaded
get_length() returns the size of the file in bytes once uploaded. Returns null prior to upload
get_contentType() returns the mime type of the file once it is uploaded. Returns null prior to upload
get_errorMessage() returns an error message should one occur. Returns null otherwise
For more details refer to this article:
http://p2p.wrox.com/content/blogs/danm/enter-asyncfileupload-control
How to add filter to the fileupload control in asp.net? I want a filter for Word Template File (.dot).
You could also do a javascript alternative to filtering it server side (you'd probably want to do that as well) but this saves the client from spending the time waiting on an upload to finish just to find out it was the wrong type.
http://javascript.internet.com/forms/upload-filter.html
So basically you just run a javascript function on submit that parses off the extension of the uploaded file and gives them an alert if its not of the right type.
You could also use document.forms[0].submit(); instead of passing the form reference through (as ASP.NET really only uses a single form (unless your doing something funky))
string fileName = fuFiles.FileName;
if(fileName.Contains(".dot"))
{
fuFiles.SaveAs(Server.MapPath("~/Files/" + fileName));
}
If you mean to filter the file extensions client/side, with the standard browser's file selector, isn't possible.
To do that you have to use a mixed type of upload, such as SWFUpload, based on a flash uploader system (that's a really nice techinque: it allows you to post more than a file at time).
The only thing you can do in standard mode is to filter the already posted file, and I suggest to use System.IO.Path namespace utility:
if (Path.GetExtension(upFile.FileName).ToUpper().CompareTo(".DOT") == 0)
{
/* do what you want with file here */
}
Check the filename of the uploaded file serverside:
FileUpload1.PostedFile.FileName
Unless you want to use java or something similar on the client, there's really not much you can do for filtering uploaded files before they're sent to the server.
Here I have a small method that I used to filter which types of files can be uploaded by the fileupload control named fuLogo.
if (fuLogo.HasFile)
{
int counter = 0;
string[] fileBreak = fuLogo.FileName.Split(new char[] { '.' });
logo = Server.MapPath("../Images/Logos/" + fileBreak[0] + counter.ToString()+ "." + fileBreak[1]);
if (fileBreak[1].ToUpper() == "GIF" || fileBreak[1].ToUpper() == "PNG")
{
while (System.IO.File.Exists(logo))
{
counter++;
logo = Server.MapPath("../Images/Logos/" + fileBreak[0] + counter.ToString() + "." + fileBreak[1]);
}
}
else
{
cvValidation.ErrorMessage = "This site does not support any other image format than .Png or .Gif . Please save your image in one of these file formats then try again.";
cvValidation.IsValid = false;
}
fuLogo.SaveAs(logo);
}
basically, I first Iterates through the directory to see if a file already exists. Should the file exist, (example picture0.gif) , it will increase the counter (to picture1.gif). It prevents that different users will overwrite each other's pictures should their pictures have the same name.