How to validate contents of a CSV file using Django forms

Question

I have a web app that needs to do the following: - Present a form to request a client side file for CSV import. - Validate the data in the CSV file or ask for another filename. At one point, I was doing the CSV data validation in the view, after the `form.is_valid()` call from getting the filename (i.e. I have the imported CSV file into memory in a dictionary using `csv.DictReader`). After running into problems trying to pass errors back to the original form, I'm now trying to validate the CONTENTS of the CSV file in the form's `clean()` method. I'm currently stumped on how to access the in memory file from `clean()` as the `request.FILES` object isn't valid. Note that I have no problems presenting the form to the client browser and then manipulating the resulting CSV file. The real issue is how to validate the contents of the CSV file - if I assume the data format is correct I can import it to my models. I'll post my forms.py file to show where I currently am after moving the code fr…

Accepted Answer

I assume that when you want to access that file is in this line inside the `clean` method:

```
f = TextIOWrapper(request.FILES['filename'].file, encoding='ASCII')
```

You can't use that line because `request` doesn't exist but you can access your form's fields so you can try this instead:

```
f = TextIOWrapper(self.cleaned_data.get('filename'), encoding='ASCII')
```

Since you have done `super.clean` in the first line in your method, that should work. Then, if you want to add custom error message to you form you can do it like this:

```
from django.forms.util import ErrorList
errors = form._errors.setdefault("filename", ErrorList())
errors.append(u"CSV file incorrect")
```

Hope it helps.

How to validate contents of a CSV file using Django forms

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