If a folder does not exist, create it

Question

I use a FileUploader control in my application. I want to save a file to a specified folder. If this folder does not exist, I want to first create it, and then save my file to this folder. If the folder already exists, then just save the file in it.

How can I do this?

Saraisaraiya

@JoeBlow - Ha - should have specified which answer is incorrect - now the page is even more confusing. (Did he change the accepted answer? or did he not? OMG!) ;-) – President

I ended up here while looking for other things, but it's amazing how many people are fighting to contradict each other with their own version of the same story. Microsoft authored the .NET Framework and the MSDN. Whether the correct behavior is respected by other implementers, such as Mono, is irrelevant to the correctness of the behavior described in MSDN. Oh, and Mono does the correct thing also, so where's the argument? – Readjustment

Possible duplicate of How do I create directory if it doesn't exist to create a file? – Bindman

Check this: codingfusion.com/Post/… – Edmonds

Answer 1

Use System.IO.Directory.CreateDirectory.

According to the official ".NET" docs, you don't need to check if it exists first.

System.io   >   Directory   >   Directory.CreateDirectory

Any and all directories specified in path are created, unless they already exist or unless some part of path is invalid. If the directory already exists, this method does not create a new directory, but it returns a DirectoryInfo object for the existing directory.

        — learn.microsoft.com/dotnet/api/

---

Kathrynkathryne

For the .NET Framework 4.5 version the actual quotation is "If the directory already exists, this method does not create a new directory, but it returns a DirectoryInfo object for the existing directory." – Doner

and yet the microsoft code example contradicts itself by checking if the directory exists first... – Pruchno

So we have to check if it exists or not? If we check and then also the CreateDirectory method check again, we make the check two times... and AFAIK filesystem operation are expensive – Genip

Except if you have a file with the same name as the directory. This will both indicate that Directory.Exists(path) is false and fail when calling CreateDirectory(path). – Intrigant

@OtávioDécio you mean file without an extension ? – Celina

@Celina like this - create a file for example "FILENAME" on a directory but don't give it any extension. Then try calling Directory.Exists("FILENAME") will return false, as it should because there is no such directory. Now if you call CreateDirectory("FILENAME") it will fail miserably as it should because there is already "something" with that name there. Hope that makes sense. – Intrigant

WRONG! I You MUST check if the folder exists. I just Identified that this method has a serious problem. If you don't check for existence of the folder, the Folder handle will leak unless you specifically release it. We used this example in an application that processes millions of folders. Every time this method was called, the application retained the file handle to the directory. After several hours, the Corporate Network NAS had millions of File Handles open on the folders. Updating to include the check free's the handle – Hissing

@soddoffBaldrick You must be doing something terribly wrong in your code, because neither Directory nor DirectoryInfo do anything with handles. Eventually, Directory.Create boils down to a chain of calls to the Win32 CreateDirectory function, and that function, again, does not do anything with handles. Your handle leak is elsewhere. – Sansone

really @TomLint? I have pretty good evidence that it does exactly that. But I was always suspicious that the SAN's SMB implementation (non-windows) is the source of the issue - so you could be right. We never saw the issue in testing, but this was on a windows server. – Hissing

@Pruchno lol. I wouldn't say it contradicts itself, it just chooses to check if it exists, you're always free to do that (you may want to know if it exists and take different action, not want the existing DirectoryInfo object returning). – Christianna

CreateDirectory() will happily create all the directories in a path. No need to put it in a loop. – Borrell

Answer 2

Use the below code as per How can I create a folder dynamically using the File upload server control?:

string subPath ="ImagesPath"; // Your code goes here

bool exists = System.IO.Directory.Exists(Server.MapPath(subPath));

if(!exists)
    System.IO.Directory.CreateDirectory(Server.MapPath(subPath));

Hemitrope

Sorry, I missed adding the link. – Hemitrope

totaldotnet.com/Tip/ShowTip22_UsePhysicalAppPath.aspx Server.MapPath vs PhysicalApplicationPath. Do you agree? – Avitzur

Why not: if (!Directory.Exists(path_to_check)) Directory.CreateDirectory(path_to_check); – Collotype

No need to check if folder exists. Read the manual carefully. – Margetts

Checking and creating is not atomic. The above code smells, there is a race condition. You should better just unconditionally create the directory, and catch a FileExists (or whatever the C# equivalent) exception in case the function is designed to throw one. – Brazier

Like others have pointed out, there is no need for the call to Exists and it actually creates a new failure condition. – Poleyn

It's unnecessary but I don't see why it would cause a race condition or new failure condition. @JoSo As pointed out in the other comments if the directory is created after the check then the call to CreateDirectory does nothing anyway. – Rockbound

@MartinSmith: Then just create the directory. Don't check for existence before. That is not only shorter. It also doesn't give a false impression of what the API of System.IO.Directory.CreateDirectory is. (And it is faster, but probably that doesn't matter) – Brazier

@JoSo - Nowhere does my comment dispute that. – Rockbound

As bazzilic said read up on CreateDirectory! "Creates all directories and subdirectories in the specified path unless they already exist." taken from msdn.microsoft.com/en-us/library/… – Ohl

Server is not defiened – Grandioso

Answer 3

Just write this line:

System.IO.Directory.CreateDirectory("my folder");

• If the folder does not exist yet, it will be created.
• If the folder exists already, the line will be ignored.

Reference: Article about Directory.CreateDirectory at MSDN

Of course, you can also write using System.IO; at the top of the source file and then just write Directory.CreateDirectory("my folder"); every time you want to create a folder.

Leff

Yup, no need to check if the directory exists. To see this, run Directory.CreateDirectory("D:/TestDir"); line two times. It will create the directory on the first line and ignore the existing directory in the second line. – Kordofanian

Answer 4

Directory.CreateDirectory explains how to try and to create the FilePath if it does not exist.

Directory.Exists explains how to check if a FilePath exists. However, you don't need this as CreateDirectory will check it for you.

Community

This enables race conditions, see the accepted answer. – Industrious

Answer 5

You can create the path if it doesn't exist yet with a method like the following:

using System.IO;

private void CreateIfMissing(string path)
{
  bool folderExists = Directory.Exists(Server.MapPath(path));
  if (!folderExists)
    Directory.CreateDirectory(Server.MapPath(path));
}

Colb

Check if (!folderExists) is not needed. – Margetts

@Margetts yes, but it reveals intent. I don't have to guess (or know for sure) how the API handles this. Anyone who reads this code will know for sure what will happen. – Colb

In multithreaded environments (such as the state of a filesystem) you only ever have the choice of locking or try-and-catch. The snippet above has a race condition. The function might throw a FileExists Exception (or whatever it's called in C#) – Brazier

"it reveals intent" -- This is not a good justification. You could just write a comment in the code. – Elstan

Answer 6

You can use a try/catch clause and check to see if it exist:

  try
  {
    if (!Directory.Exists(path))
    {
       // Try to create the directory.
       DirectoryInfo di = Directory.CreateDirectory(path);
    }
  }
  catch (IOException ioex)
  {
     Console.WriteLine(ioex.Message);
  }

Job

This is a good answer, but, according to the MSDN documentation, "Any and all directories specified in path are created, unless they already exist or unless some part of path is invalid. The path parameter specifies a directory path, not a file path. If the directory already exists, this method does nothing." So, you don't really need the call to Directory.Exists(path). – Expiation

That's true but that's also an assumtion so it's always best to check rather than to assume regardless of what MSDN Says.. – Job

@DJ KRAZE, I believe MSDN unless it has been proven to be wrong. You recommend the opposite - ignore what MSDN says and add extra (unnecessary) checks into your code. Where do you draw the line? – Kreegar

ShellShock nowhere do I say ignore.. this is a persumtious statement I am saying it's better to not assume than to assume.. read what i have stated once again.. thanks – Job

@DJKRAZE nobody's assuming anything. It is written in plain english in the manual that check is not necessary. – Margetts

The one benefit of a check is that it creates an opportunity for meaningful logging. But certainly not needed for the basic mechanics. – Croissant

It could fail for other reasons, e.g. a virus checker kicking in at the worst possible time. – Exquisite

Answer 7

This method will create the folder if it does not exist and do nothing if it exists:

Directory.CreateDirectory(path);

Undress

How is this different from the answers from 2012? – Exquisite

Answer 8

if (!Directory.Exists(Path.GetDirectoryName(fileName)))
{
    Directory.CreateDirectory(Path.GetDirectoryName(fileName));
}

Guelders

CreateDirectory already handles the check if the directory does not exists. – Griz

Answer 9

using System.IO

if (!Directory.Exists(yourDirectory))
    Directory.CreateDirectory(yourDirectory);

Lati

Answer 10

Create a new folder, given a parent folder's path:

string pathToNewFolder = System.IO.Path.Combine(parentFolderPath, "NewSubFolder");
DirectoryInfo directory = Directory.CreateDirectory(pathToNewFolder); 
// Will create if does not already exist (otherwise will ignore)

• path to new folder given
• directory information variable so you can continue to manipulate it as you please.

Purebred

Answer 11

The following code is the best line(s) of code I use that will create the directory if not present.

System.IO.Directory.CreateDirectory(HttpContext.Current.Server.MapPath("~/temp/"));

If the directory already exists, this method does not create a new directory, but it returns a DirectoryInfo object for the existing directory. >

Perron

CreateDirectory already handles the check if the directory does not exists. – Griz

@Griz ,Thanks .I just crossed checked .It really removed conditional check .Updated !! – Perron

Answer 12

Use this code if the folder is not presented under the image folder or other folders

string subPath = HttpContext.Current.Server.MapPath(@"~/Images/RequisitionBarCode/");

bool exists = System.IO.Directory.Exists(subPath);
if(!exists)
    System.IO.Directory.CreateDirectory(subPath);

string path = HttpContext.Current.Server.MapPath(@"~/Images/RequisitionBarCode/" + OrderId + ".png");

Satirize

Answer 13

Use the below code. I use this code for file copy and creating a new folder.

string fileToCopy = "filelocation\\file_name.txt";
String server = Environment.UserName;
string newLocation = "C:\\Users\\" + server + "\\Pictures\\Tenders\\file_name.txt";
string folderLocation = "C:\\Users\\" + server + "\\Pictures\\Tenders\\";
bool exists = System.IO.Directory.Exists(folderLocation);

if (!exists)
{
   System.IO.Directory.CreateDirectory(folderLocation);
   if (System.IO.File.Exists(fileToCopy))
   {
     MessageBox.Show("file copied");
     System.IO.File.Copy(fileToCopy, newLocation, true);
   }
   else
   {
      MessageBox.Show("no such files");
   }
}

Apatite

An explanation would be in order. It seems to do some more checks(?). – Exquisite

Answer 14

A fancy way is to extend the FileUpload with the method you want.

Add this:

public static class FileUploadExtension
{
    public static void SaveAs(this FileUpload, string destination, bool autoCreateDirectory) { 

        if (autoCreateDirectory)
        {
            var destinationDirectory = new DirectoryInfo(Path.GetDirectoryName(destination));

            if (!destinationDirectory.Exists)
                destinationDirectory.Create();
        }

        file.SaveAs(destination);
    }
}

Then use it:

FileUpload file;
...
file.SaveAs(path,true);

Coastwise

But class FileUploadExtension is not used anywhere(?). – Exquisite

What do you mean by "extend the FileUpload"? – Exquisite

@PeterMortensen learn.microsoft.com/en-us/dotnet/csharp/programming-guide/…. In my solution, the SaveAs method have another version with a second parameter that tells to create or not the directory. The name of the class that holds the new method has to be different from the class that i am extending. That may cause confusion, but that is the way it is. – Coastwise

Answer 15

By looking at the answers above, clearly lots of people are still not aware of the "Directory.CreateDirectory", or they don't read the official documentation carefully.

Syncopate

Nearly all of the top-voted answers reference this. What, specifically, is your critique? – Shaunshauna

While this link may answer the question, it is better to include the essential parts of the answer here and provide the link for reference. Link-only answers can become invalid if the linked page changes. - From Review – Hooligan

Answer 16

string root = @"C:\Temp";

string subdir = @"C:\Temp\Mahesh";

// If directory does not exist, create it.

if (!Directory.Exists(root))
{

Directory.CreateDirectory(root);

}

The CreateDirectory is also used to create a sub directory. All you have to do is to specify the path of the directory in which this subdirectory will be created in. The following code snippet creates a Mahesh subdirectory in C:\Temp directory.

// Create sub directory

if (!Directory.Exists(subdir))
{

Directory.CreateDirectory(subdir);

}

Stutter

Answer 17

Derived/combined from multiple answers, implementing it for me was as easy as this:

public void Init()
{
    String platypusDir = @"C:\platypus";
    CreateDirectoryIfDoesNotExist(platypusDir);
}

private void CreateDirectoryIfDoesNotExist(string dirName)
{
    System.IO.Directory.CreateDirectory(dirName);
}

Urethra

What is the point of encapsulating a method into what is essentially an exact copy, with only a slightly different name? You literally gain nothing from this. – Chantay

@Chantay One reason for the encapsulation may be documentation. It is unclear that the directory is only created if it does not exist from the CreateDirectory statement alone. But as someone in this thread had mentioned, he could just write a comment to explain that. – Bevatron