How to Rename an Image or File in an Upload in Django

In this article, we show how to rename an image or file in an upload in Django.

If you're running a Django site live on the web and you're using cloud storage, for example, such as amazon web services (aws), you want to ensure that there are no naming conflicts within a given directory. For example, if you have a file named dog.png in a directory and then another user uploads another file with the same exact file name (dog.png), the original dog.png file will be overwritten. This is largely unintended.

However, there are ways we can implement our Django code so that this does not happen.

For one thing, we can create a custom path for our image or file, so that all pictures by a certain user is separate from those from other users.

However, this alone doesn't solve the issue, because a certain user can upload multiple files with the same name. So, we have to give each file a unique name. And we can do this by appending a random string after the file name.

So let's see how this is actually done.

So below we have code that creates a unique file name for every file or image uploaded to the model.

def photo_path(instance, filename): basefilename, file_extension= os.path.splitext(filename) chars= 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz1234567890' randomstr= ''.join((random.choice(chars)) for x in range(10)) return 'images/userphotos/{userid}/{basename}{randomstring}{ext}'.format(userid= instance.user.id, basename= basefilename, randomstring= randomstr, ext= file_extension) class UserPhoto(models.Model): user= models.ForeignKey(User) photo= models.ImageField(upload_to= photo_path, null=True) ....

So we create a custom function, photo_path, that takes in 2 parameters.

instance refers to the instance of the model, in this case, UserPhoto.

filename refers to the original name of the file uploaded by the user.

Next, I create 2 variables, basefilename and file_extension from the variable, filename

basefilename represents the name of the file before the extension. file_extension is the extension of the file

Since we will create a random string, we specify in the variable, chars, which characters we include for this random string. In this case, we include all lowercase and uppercase alphabetical characters, as well as all digits.

We then create a variable, randomstr, that creates a random string that is 10 characters in length. You can change this to whatever length you want.

We then put what the function returns with the return statement. The function will return the path, images/userphotos/{userid}/{basename} {randomstring}{ext}, where userid is the id of the user entered into the model, basename is the base file name of the filename, randomstring is the random-generated string, and ext is the file extension of the file name.

Thus, now even if the user uploads 2 images with the same exact file name, since a random string is generated for each image, the file names are unique and naming conflicts don't arise.

So this is a pretty competent way of doing it.

You may ask, why can't we use the id of the uploaded file as a unique identifier? ids are only fields that are unique for a given model. The reason we can't do is because the id of the newly uploaded file has not been saved yet, so an id has not been given to the image or file. Thus, this is why we take the route of creating of generating a random string and appending it after the filename.

And this is how to rename an image or file in an upload in Django.

Related Resources

How to Create a File Uploader with Python in Django

How to Create an Image Uploader with Python in Django