Issue with parsing csv from Django web form

Question

I was hoping someone could help me with this. I'm getting a file from a form in Django, this file is a csv and I'm trying to read it with Python's library csv. The problem here is that when I apply the function csv.reader and I turn that result into a list in order to print it, I find out that csv.reader is not splitting correctly my file. Here are some images to show the problem

This is my csv file:

This my code:

And this is the printed value of the variable file_readed:

As you can see in the picture, it seems to be splitting my file character by character with some exceptions. I thank you for any help you can provide me.

Can you please put your code and data into code blocks? meta.stackexchange.com/questions/22186/… — rovyko
– rovyko, Commented Feb 24, 2019 at 22:37

rovyko · Accepted Answer · 2019-02-24 22:35:14Z

2

If you are pulling from a web form, try getting the csv as a string, confirm in a print or debug tool that the result is correct, and then pass it to csv using StringIO.

from io import StringIO
import csv

csv_string = form.files['carga_cie10'].file_read().decode(encoding="ISO-88590-1")
csv_file = StringIO(csv_string)
reader = csv.reader(csvfile, delimiter=',', quotechar='"')
for row in reader:
    print(row)

Another thing you can try is changing the lineterminator argument to csv.reader(). It can default to \r\n but the web form might use some other value. Inspect the string you get from the web form to confirm.

edited Feb 24, 2019 at 22:35

answered Feb 24, 2019 at 22:29

rovyko

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2 Comments

rovyko Over a year ago

I misread your question. Can you try getting a string from the web form and see if that looks correct to you?

Juan Pablo Over a year ago

Thank you, brother, this worked perfectly for me and it's splitting everything correctly. You really saved my day!

lupodellasleppa · Accepted Answer · 2019-02-24 22:18:03Z

0

that CSV does not seem right: you got some lines with more arguments than others.

The acronym of CSV being Comma Separated Values, you need to have the exact same arguments separated by commas for each line, or else it will mess it up.

I see in your lines you're maybe expecting to have 3 columns, instead you got lines with 2, or 4 arguments, and some of them have an opening " in one argument, comma, then closing " in the second argument

check if your script works with other CSVs maybe

answered Feb 24, 2019 at 22:18

lupodellasleppa

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2 Comments

Juan Pablo Over a year ago

I was reading that csv manually and using the function split, the problem were those columns with the " opening. I searched and found out that csv reader will split correctly those columns. As for the empty columns, I have worked with csv that had empty columns and it worked perfectly.

lupodellasleppa Over a year ago

what about the overflowing ones?

Koray B · Accepted Answer · 2019-02-24 22:19:31Z

0

Most likely you need to specify delimiter. Since you haven't explicitly told about the delimiter, I guess it's confused.

csv.reader(csvfile, delimiter=',')

However, since there are quotations with comma delimiter, you may need to alter the default delimiter on the CSV file's creation too for tab or something else.

answered Feb 24, 2019 at 22:19

Koray B

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2 Comments

Juan Pablo Over a year ago

I have already try specifying the delimiter and it didn't work.

Koray B Over a year ago

I guess you need to alter delimiter on the file creation by changing default delimiter to semi-colon or tab. Then it'll be able to read. Because you have more commas than 2 on 3rd line of CSV.

MonteCarloSims · Accepted Answer · 2019-02-24 22:58:44Z

0

The problem is here:

print(list(file_readed))

'list' is causing printing of every element within the csv as an individual unit.

Try this instead:

with open('carga_cie10') as f:
reader = csv.reader(f)
for row in reader:
    print(" ".join(row))

Edit:

import pandas as pd
file_readed = pd.read_csv(file_csv)
print(file_readed)

The output should look clean. Pandas is highly useful in situations where data needs to be read, manipulated, changed, etc.

edited Feb 24, 2019 at 22:58

answered Feb 24, 2019 at 22:21

MonteCarloSims

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2 Comments

Juan Pablo Over a year ago

The thing is that I do not have physcally the file, I'm getting directly from the form, so I haven't been able to open the file like that.

MonteCarloSims Over a year ago

Editing to suggest using Pandas instead.

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