python django csv django-models filefield

How is the file from OneToOne Model's FileField accessed, read in views.py and passed to template?

I am developing a simple Data Visualization App, where a user can register, login upload a file and visualize its content.

I am using default User model, and a Detail Model having OneToOne relation with User Model. The Detail has 3 fields, which are:

OneToOne(User)
FileField()
TextField()

Now, I want to access the file that is saved in FileField, in views.pyand read it's content, then visualize it using Python'sNumPyandMatplotlib`, then finally show visualization results on the frontend.

I need a guidance that how should I start and approach this task? Basically, I need deep guidance in how to access and read the file in views.py?

My models.py is:

class Detail(models.Model):
    user = models.OneToOneField(User, on_delete=models.CASCADE)
    file = models.FileField(verbose_name="CSV File", upload_to='csv_files/')
    file_desc = models.TextField("CSV File Description")

    def __str__(self):
        return ("{} ({} {})".format(self.user.email, self.user.first_name, self.user.last_name))

and in views.py, I am approaching it this way:

class VisualizeAPI(View):
    template_name = 'accounts/visualize.html'

    def get(self, request):
        msg = {'message': "Please login to view this page."}
        
        if request.user.is_authenticated:
            detail, _ = Detail.objects.get_or_create(user=request.user)
            context = {'detail': detail}

            return render(request, self.template_name, context)

        return render(request, self.template_name, msg)

and in template, I am approaching it this way:

<body>
    <h1>Visualized Details</h1>
 
    {% if request.user.is_authenticated %}
    {{ detail }}
    {% else %}
    <h2>{{ message }}</h2>
    {% endif %}
</body>

But it is not printing the content of the file on the frontend. I will be glad for proper approach and guidance provided.

Solution

You need to parse the CSV file in your view and then pass it to your template.

import csv
from io import StringIO


class VisualizeAPI(View):
    template_name = "accounts/visualize.html"

    def get(self, request):
        msg = {"message": "Please login to view this page."}

        if request.user.is_authenticated:
            detail, _ = Detail.objects.get_or_create(user=request.user)
            if detail.file:
                # Read file from detail object
                file = detail.file.read().decode("utf-8")
                # Parse file as csv
                csv_data = csv.reader(StringIO(file), delimiter=",")
            else:
                csv_data = None
            context = {
                "detail": detail,
                "csv_data": csv_data,
            }

            return render(request, self.template_name, context)

        return render(request, self.template_name, msg)

Then you can print each row of your csv file in your template.

<body>
  <h1>Visualized Details</h1>

  {% if request.user.is_authenticated %}
  {{ detail }}
  {% for row in csv_data %}
    {{ row }}
  {% endfor %}
  {% else %}
  <h2>{{ message }}</h2>
  {% endif %}
</body>