How to implement CSV Writer in a named temporary

Basically, I need final a csv file, whose contents look like Header, and then the data: (Boto3 upload_file does the job of writing temporary file, into csv)

Expectation:

Name,Code
Adam,12

I am able to get this, by using:

with tempfile.NamedTemporaryFile(mode="a t", suffix =".csv", delete=True) as fileName:
   for data in allData:
      fileName.write(data)
      fileName.flush()

Additional doubt: without this flush(), all of the data do not come in the final csv. flush() clears the buffer memory, I presume. So, is there a way to check, if the memory is getting full, and the remaining data are left out?

But, when I am using csv.writer:

writer = csv.write(fileName)
with tempfile.NamedTemporaryFile(mode="a t", suffix =".csv", delete=True) as fileName:
   for data in allData:
      writer.writerow(data)

Reality:

N,a,m,e","C,o,d,e
A,d,a,m","1,2"

Using Python 3.8

A data looks like: Adam,12

Need help writing this with csv writer. I have seen references of StringIO being used to fix similar cases, but do not know how to implement. Is there a way out?

CodePudding user response：

This doesn't have anything to do with the temporary directory.

Here is part of the introduction about CSV writer objects (bold added):

A row must be an iterable of strings or numbers for Writer objects and a dictionary mapping fieldnames to strings or numbers... for DictWriter objects

But you are passing in a single string: "Adam,12". So what's going on?

Strings themselves are iterables over the characters in the string:

>>> for character in "Adam":
...     print(character)
...
A
d
a
m

And since Python doesn't have a distinct character class, each of those single-character values is also a string. So strings are iterables of strings.

When you give an iterable of strings to csvwriter.writerow(), it writes each string in the iterable to its own column. In this case, that means one-character strings taken from the input.

To get the behaviour you're after, you'll need to pass something like ["Adam", 12] (not "Adam,12") to the CSV writer. I'm not sure where your inputs are coming from, so there might be a better way to do this, but you could split your strings on the comma as you pass them in:

for data in allData:
    writer.writerow(data.split(","))

This works because "Adam,12".split(",") returns ["Adam", "12"]. Note that this won't work properly if your inputs have multiple commas.