Error on writing to csv file

[jokiehints]

@cvp OK thanks, I understand. Ik hope somewone else can give me the tips I need.

[cvp]

@jokiehints Really not sure that I correctly understood, if not, sorry and forget this post

import csv
import os

values = {}
def set(fieldname,value):
	values[fieldname] = value
		
set('geb_dag',10)
set('geb_maand',19)

file = 'data.csv'
header = not os.path.exists(file)

with open(file, 'a', newline='') as csvfile:
    fieldnames = ['geb_dag','geb_maand']
    writer = csv.DictWriter(csvfile, fieldnames=fieldnames)

    if header:
      writer.writeheader()
    writer.writerow(values)

[jokiehints]

@cvp Thank you so much for your effort. Unfortunately this code isn't working for the format I want to get for my CSV file (as I described above). But please don't worry. I will continue with my search for a solution for this. Thanks again.

[JonB]

What is the problem with cvp's solution? Does it still write the extra header row?

Your problem was that you were calling

writer.writeheader()

When you were appending. Presumably that is now solved... But is there another issue?

[cvp]

@JonB In his first post after my answer about external files, he describes two problems a first and a second...
And I'm not sure to understand the second

Second: Even beter I want the CSV go to a horizontal presentation like:

[JonB]

I'll point out that you should delete the data.csv after implementing the changes, otherwise the old errors will still be there

[cvp]

@JonB I did it before each test, hoping he did the same

[mikael]

I think he actually wanted a ”transposed” layout.

@jokiehints said:

geb_dag, geb_mnd, geb_jr, vnaam, a_naam,
19, 10, 1981, 2, 5

Which should be an easy change to @cvp’s code.

[JonB]

ahh, in that case, you cannot use append for the file mode, but instead must read the whole file in first, append the date, then write it out again. ..

[cvp]

@JonB yes but only if you change fields names, not if you add new records to existing variables.