Python - How to create new Json file after every loop?

Question

So I have a CSV file that I convert later on to a JSON file. However what I want to do is that I want to save to a new json file for every json objects that is new. Meaning something like this:

{
"first_name": "Hello",
"last_name": "World",
"color": "black"
},

{
"first_name": "Stack",
"last_name": "Overflow",
"color": "Red"
}

How I change it to a format from CSV to JSON is that I create it as a dict where I have the CSV format and a fieldsname that is created based on "first_name", "last_name_" and color.

It would look like something like:

jsonfile = open('newfilejson.json', 'w')
fieldnames = ("first_name","last_name","color")
reader = csv.DictReader(csvfile, fieldnames)

for row in reader:
    jsonfile.write('"first_name": "' + row['first_name'] + '",\n')
    jsonfile.write('"last_name": "' + row['last_name'] + '",\n')
    jsonfile.write('"color": "' + row['color'] + '",\n')

however this will just save into one file basically and my question is:

How can I make so everytime it finished one "row" from the for-loop to create a new json file that contains whats inside the for-loop (With write) and then whenever there is new, it creates a new json file. Basically meaning that everytime a row is finished, create new json?

Use an additional for-loop around most code (except the two lines for opening the CSV-file) in which you open, write and close a new JSON-file on each iteration. — Michael Butscher
– Michael Butscher, Commented Oct 4, 2018 at 20:07
@MichaelButscher But do I need to create the json file before hand to be able to write it? — WeInThis
– WeInThis, Commented Oct 4, 2018 at 20:10
Yes, you must first create (and open, which is the same operation here) a file before you can write to it. — Michael Butscher
– Michael Butscher, Commented Oct 4, 2018 at 20:11
you want to open a json & create another json file for each csv row? or to open a json & make a csv row saved in a json? your explanation & code kind of contradicts each other, i'm confused. — deadvoid
– deadvoid, Commented Oct 4, 2018 at 20:13
Do you really want to write a zillion separate JSON files? Why not a single JSON file containing a list of those dict objects? — PM 2Ring
– PM 2Ring, Commented Oct 4, 2018 at 20:14

Ralf · Accepted Answer · 2018-10-04 20:12:18Z

2

You could try this:

for row in reader:
    filename = 'a_file_{}'.format(row['first_name'])
    with open(filename, 'w') as f:
        f.write('"first_name": "' + row['first_name'] + '",\n')
        f.write('"last_name": "' + row['last_name'] + '",\n')
        f.write('"color": "' + row['color'] + '",\n')

You just need to decide how these files should be named. My example uses the first name in the filename.

answered Oct 4, 2018 at 20:12

Ralf

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WeInThis Over a year ago

I used this and it helped me what I wanted to achieve! Thanks alot! :)

pythomatic · Accepted Answer · 2018-10-04 20:12:36Z

2

You can use a context manager to open and write to a new json file for each row:

fieldnames = ("first_name","last_name","color")
reader = csv.DictReader(csvfile, fieldnames)

for row in reader:
    with open('%s_%s.json' % (row['first_name'], row['last_name']), 'w') as jsonfile:
        jsonfile.write('"first_name": "' + row['first_name'] + '",\n')
        jsonfile.write('"last_name": "' + row['last_name'] + '",\n')
        jsonfile.write('"color": "' + row['color'] + '",\n')

answered Oct 4, 2018 at 20:12

pythomatic

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