Django File Handling And Uploading

When building web applications, file uploading is a common task. In this guide, we'll go over how to handle file uploads from users in Django, store those files in a MySQL database, and retrieve and display the files for preview and download.

Prerequisites

Before we start, ensure that you have the following:

• Django project with MySQL configured
• Basic understanding of Django models, views, and templates

Step 1: Setting Up The Model

We'll create a model that will handle file uploads and store the file details in our MySQL database.

models.py

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from django.db import models

class UploadedFile(models.Model):
    file = models.FileField(upload_to='uploads/')
    uploaded_at = models.DateTimeField(auto_now_add=True)

    def __str__(self):
        return self.file.name

• FileField: This is used to store files in Django.
• upload_to='uploads/': Uploaded files will be stored in the uploads directory within your MEDIA_ROOT.

Step 2: Configuring Settings

In your settings.py, configure Django to store uploaded files and serve them during development.

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import os

MEDIA_URL = '/media/'
MEDIA_ROOT = os.path.join(BASE_DIR, 'media')

INSTALLED_APPS = [
    # Other apps
    'django.contrib.staticfiles',
]

Step 3: Creating A File Upload Form

We need to create a form to allow users to upload files.

forms.py

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from django import forms
from .models import UploadedFile

class FileUploadForm(forms.ModelForm):
    class Meta:
        model = UploadedFile
        fields = ['file']

Step 4: Handling the Upload In Views

Now let's create a view that handles the file upload and displays the list of uploaded files.

views.py

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from django.shortcuts import render, redirect
from django.http import HttpResponse
from .forms import FileUploadForm
from .models import UploadedFile
import os
from django.conf import settings
from django.http import FileResponse

def file_upload_view(request):
    if request.method == 'POST':
        form = FileUploadForm(request.POST, request.FILES)
        if form.is_valid():
            form.save()
            return redirect('file_list')
    else:
        form = FileUploadForm()

    return render(request, 'file_upload.html', {'form': form})

def file_list_view(request):
    files = UploadedFile.objects.all()
    return render(request, 'file_list.html', {'files': files})

def file_download_view(request, file_id):
    file = UploadedFile.objects.get(id=file_id)
    file_path = os.path.join(settings.MEDIA_ROOT, file.file.name)
    return FileResponse(open(file_path, 'rb'), as_attachment=True)

def file_preview_view(request, file_id):
    file = UploadedFile.objects.get(id=file_id)
    file_path = os.path.join(settings.MEDIA_ROOT, file.file.name)

    if file.file.name.endswith(('.png', '.jpg', '.jpeg')):
        return render(request, 'file_preview.html', {'file': file})
    return HttpResponse("Preview not available for this file type.")

• file_upload_view: Handles the file upload form.
• file_list_view: Displays all uploaded files.
• file_download_view: Allows users to download files.
• file_preview_view: Provides a preview for image files (JPG, PNG, etc.).

Step 5: Creating Templates

We need three templates: one for the file upload form, one to list files, and one for previews.

file_upload.html

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<form method="post" enctype="multipart/form-data">
    {% csrf_token %}
    {{ form.as_p }}
    <button type="submit">Upload File</button>
</form>

file_list.html

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<h2>Uploaded Files</h2>
<ul>
    {% for file in files %}
        <li>
            <a href="{% url 'file_preview' file.id %}">{{ file.file.name }}</a> |
            <a href="{% url 'file_download' file.id %}">Download</a>
        </li>
    {% endfor %}
</ul>

file_preview.html (for image previews)

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<h2>Preview File: {{ file.file.name }}</h2>
<img src="{{ file.file.url }}" alt="{{ file.file.name }}">

Step 6: Setting Up URLs

Configure your URLs to map to the appropriate views.

App-level urls.py

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from django.urls import path
from . import views

urlpatterns = [
    path('upload/', views.file_upload_view, name='file_upload'),
    path('files/', views.file_list_view, name='file_list'),
    path('files/download/<int:file_id>/', views.file_download_view, name='file_download'),
    path('files/preview/<int:file_id>/', views.file_preview_view, name='file_preview'),
]

Step 7: Handling Media Files In Development

To serve uploaded files during development, update urls.py to serve media files.

Project-level urls.py

The project-level is the directory with the asgi.py, settings.py, wsgi.py and urls.py files.

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from django.conf import settings
from django.conf.urls.static import static

urlpatterns += static(settings.MEDIA_URL, document_root=settings.MEDIA_ROOT)

Step 8: Migrate the Database

After creating the model, run the migrations to add it to the MySQL database.

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python manage.py makemigrations
python manage.py migrate

Conclusion

We have successfully set up file uploading in Django with the ability to store, retrieve, preview, and download files. The files are stored in the file system, while the metadata is saved in a MySQL database. This setup is easily extensible for different file types, and you can further customize the file handling process depending on your project's needs.