how to solve a must be string not list error in python?

Question

I got an error."must be str, not list".

import os
import shutil
tesst = onlyfiles
tesst = []
with open('C:/Users/eGeneration Lab/Documents/project/try/data/final.txt') as f:
 found = 2
 for line in f:
 if tesst in onlyfiles: 
 found = 1
if found == 1: 
 shutil.move('C:/Users/eGeneration Lab/Documents/project/try/data/'+tesst,'C:/Users/eGeneration Lab/Documents/project/try/programs/error/'+tesst)
else:
 shutil.move('C:/Users/eGeneration Lab/Documents/project/try/data/'+tesst,'C:/Users/eGeneration Lab/Documents/project/try/programs/working/'+tesst)
 with open("C:/Users/eGeneration Lab/Documents/project/try/data/final.txt", "a") as f:
 f.write(tesst+"\n")
TypeError: must be str, not list

• Ahmad Moussa: Maybe you should cast the object to a string? Anyway, your question is not clear at all...
• Mureinik: Can you please share the entire stacktrace?
• Albin Paul: you are writing a list to a file you can only write strings to a file convert the list to string in whichever format you want just str(tesst) might work now but not applicable for every case
• ZF007: Your code makes no sense at all. Tesst is overwriten by an empty list; whereas the 'tesst' in first place refers to something that is not even in your code script. So either include that "onlyfiles", explain what it does or is and how we should handle it or just post some sort of hook to use it. List to files writing is not permitted. Only strings. You can do for x in tesst: write x to file.

Answer 1

tesst = []
f.write(tesst+"\n") #Error occurs: TypeError: must be str, not list
f.write("".join(tesst)+"\n") # working [list to string]
f.write("\n".join(tesst)) #is better insert `\n`

Answer 2

If you are using python3.6+, the code can be as follows:

import shutil
from pathlib import Path
BASE_DIR = "C:/Users/eGeneration Lab/Documents/project/try"
data_path = Path(BASE_DIR) / "data"
error_path = Path(BASE_DIR) / "programs" / "error"
working_path = Path(BASE_DIR) / 'programs' / 'working'
final_file = data_path / "final.txt"
tesst = onlyfiles
tesst = []
with final_file.open() as fp:
 found = 2
 for line in fp:
 if tesst in onlyfiles:
 found = 1
if found == 1:
 shutil.move(data_path / tesst, error_path / tesst)
else:
 shutil.move(data_path / tesst, working_path / tesst)
 with final_file.open("a") as fp:
 fp.write(f"{tesst}\n")