In this blog, the goal is to show the capabilities of Django’s built-in Fields, specifically Django FileField, for storing files. Every experienced web developer had to work with files at one point. Files can be stored in a database in many ways, either locally or on a server.<\/p>\n\n\n\n
So what actually is FileField in Django?<\/p>\n\n\n\n
Django FileField inherits an abstract Field class representing the database table column, and it is used for simple file uploads.<\/strong><\/p>\n\n\n\n Before we go into a more detailed explanation of the FileField parameters, we will define one model with a Let’s look at how FileField behaves in the database and what we use it for.<\/p>\n\n\n\n For the specified model after And after migrating We see one interesting thing, FileField is stored in the Postgres database as Character Varying<\/strong>. <\/p>\n\n\n\n What would that mean for our files? Where do they end up? <\/p>\n\n\n\n Our files are stored locally on the computer<\/strong>. So in this example, the FileField or Let’s look at the FileField parameters.<\/p>\n\n\n\n FileField has 2 optional parameters<\/strong>. Let’s see in the following example what these parameters actually mean.<\/p>\n\n\n\n Finally, let’s look at an example of a saved book in the database:<\/p>\n\n\n\n Although we have defined the directory in which we save the files, it is still not the best practice. Define next in your settings.py.<\/strong><\/p>\n\n\n\n From the moment we define MEDIA_ROOT, all subsequent files we upload will be saved in Now that we have successfully saved our files to the computer. How can we retrieve these files?<\/p>\n\n\n\n We access our files via URL with the exposed path to the file. We simply send a GET request <\/strong>to More precisely: So why is that so? It is quite simple, we previously defined the MEDIA folder, and it now stores files. We just have to expose that file in URLs<\/strong>, so we can then access everything in it in the following way: Let’s see how to expose a URL. Set the following in root URLs:<\/p>\n\n\n\n Now that we’ve exposed the files, we can finally retrieve the file via URL. Assuming you’re running this locally, let’s type the following:<\/p>\n\n\n\n In this example, considering The uploaded pdf is displayed in the web browser, and we get: Object-relational mapping helps us create queries over the database without writing actual SQL queries.<\/strong> So it can be pretty handy.<\/p>\n\n\n\n In the following example, we will show what can be done with Django ORM.<\/p>\n\n\n\npdf_file<\/code> column. <\/p>\n\n\n\nclass Book(models.Model):\n title = models.CharField(max_length=255)\n published_date = models.DateTimeField(null=True)\n\n pdf_file = models.FileField()<\/pre>\n\n\n\n
Django FileField in Database<\/h2>\n\n\n\n
python manage.py makemigrations<\/code> the following migration file is obtained.<\/p>\n\n\n\nclass Migration(migrations.Migration):\n\n initial = True\n\n dependencies = [\n ]\n\n operations = [\n migrations.CreateModel(\n name='Book',\n fields=[\n ('id', models.BigAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),\n ('title', models.CharField(max_length=255)),\n ('published_date', models.DateTimeField(null=True)),\n ('pdf_file', models.FileField(upload_to='')),\n ],\n ),\n ]<\/pre>\n\n\n\npython manage.py migrate<\/code> we get the following data structure in the database:<\/p>\n\n\n\nName<\/strong><\/td> Data Type<\/strong><\/td> Database Example<\/strong><\/td><\/tr> id<\/td> Big int<\/td> 2<\/td><\/tr> title<\/td> Character Varying (255)<\/td> Django FileField Book<\/td><\/tr> published_date<\/td> Timestamp with time zone<\/td> 2022-01-19 16:56:03+01<\/td><\/tr> pdf_file<\/td> Character Varying (100)<\/td> django_filefield_book.pdf<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n pdf_file<\/code> column in the database would save the path of our file.<\/p>\n\n\n\nDjango FileField parameters<\/h2>\n\n\n\n
class FileField(upload_to=None, max_length=100, **options)<\/code><\/p>\n\n\n\npdf_file = models.FileField(upload_to='uploads\/', max_length=255, **options)<\/code><\/p>\n\n\n\nupload_to<\/code> specifies the route to which a particular file will be saved. For example, book.pdf will be saved in the BASE_DIR\/uploads<\/code> directory, the file name and folder in which the file is located will be saved in the database.<\/li>max_length<\/code> determines the maximum length of the saved path. The default is 100<\/strong>. If you have files and paths with long names, you must not forget to change this parameter. Otherwise, you might get DatabaseError: value too long for type character varying (100)<\/code>.<\/li><\/ul>\n\n\n\nid<\/strong><\/td> title<\/strong><\/td> published_date<\/strong><\/td> pdf_file<\/strong><\/td><\/tr> 1<\/td> Book<\/td> 2022-01-19 19:49:22+01<\/td> uploads\/book.pdf<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
According to the official Django documentation, the files should be saved in the MEDIA folder<\/strong>. The media folder should be defined in the Django settings, so let’s show what it should look like.<\/p>\n\n\n\nMEDIA_ROOT = os.path.join(BASE_DIR, 'media') \nMEDIA_URL = '\/media\/'<\/pre>\n\n\n\n
media\/uploads\/<\/code> <\/strong>because we defined upload_to = 'uploads'<\/code>. But only the file path upload_to + file_name<\/code> is saved in the database.<\/p>\n\n\n\nHow to access FileField files?<\/h2>\n\n\n\n
So let’s try to access our file saved in media\/uploads\/book.pdf<\/code><\/p>\n\n\n\nhttp:\/\/127.0.0.1:8000\/media\/uploads\/book.pdf<\/code>, but we get: Not Found: \/media\/uploads\/book.pdf<\/code><\/p>\n\n\n\n\"GET \/media\/uploads\/book.pdf HTTP\/1.1\" 404<\/code><\/p>\n\n\n\n
This happens because the path is not defined in urls.py<\/strong>, i.e., Django tries to find a valid path to the file we are looking for, but as it does not find the right URL, it concludes that it does not exist.<\/p>\n\n\n\n
So the next step is to define a valid URL, but since files can be named differently, how do we do that?<\/p>\n\n\n\nhost + media_root + upload_to<\/code> parameter (what is saved in the database as varchar)<\/p>\n\n\n\nfrom django.conf import settings\nfrom django.conf.urls.static import static\n\nurlpatterns += static(settings.MEDIA_URL, document_root=settings.MEDIA_ROOT)<\/pre>\n\n\n\n
WARNING<\/strong> - use this only in Development! This method of serving static files is NOT safe in production. Read more in the official Django documentation<\/a><\/pre>\n\n\n\n
http:\/\/127.0.0.1:8000\/ + media\/ + upload_to parameter<\/pre>\n\n\n\n
upload_to<\/code> parameter is uploads\/book.pdf:<\/p>\n\n\n\nhttp:\/\/127.0.0.1:8000\/media\/uploads\/book.pdf<\/pre>\n\n\n\n
\"GET \/media\/uploads\/book.pdf HTTP \/ 1.1\" 200<\/code><\/p>\n\n\n\nNOTE<\/strong> - Occasionally we can get a response with status code 304. No need to worry, it's a redirection to a cached resource.<\/pre>\n\n\n\n
FileField with Django ORM<\/h2>\n\n\n\n
# Filters books using string manipulation of pdf_file\nBook.objects.filter(pdf_file__exact='uploads\/book.pdf')\nBook.objects.filter(pdf_file__iexact='uploads\/BOOK.pdf')\nBook.objects.filter(pdf_file__contains='book')\nBook.objects.filter(pdf_file__endswith=\".pdf\")\nBook.objects.filter(pdf_file__startswith=\"uploads\")\n \n# Filters books using regex\nBook.objects.filter(pdf_file__regex='book')\n \n# Filters books by existing pdf_file\nBook.objects.filter(pdf_file__isnull=False)\n \n# Filters books by given array of pdf_files\nBook.objects.filter(pdf_file__in=['uploads\/book.pdf'])<\/pre>\n\n\n\n