CODEWITHSUNDEEP
pythonjson
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Reputation: 182

How to copy a JSON file in another JSON file, with Python

I want to copy the contents of a JSON file in another JSON file, with Python

Any ideas ?

Thank you :)

Upvotes: 2

Views: 17766

Answers (1)

Gareth Latty
Gareth Latty

Reputation: 89027

Given the lack of research effort, I normally wouldn't answer, but given the poor suggestions in comments, I'll bite and give a better option.

Now, this largely depends on what you mean, do you wish to overwrite the contents of one file with another, or insert? The latter can be done like so:

with open("from.json", "r") as from, open("to.json", "r") as to:
    to_insert = json.load(from)
    destination = json.load(to)
    destination.append(to_insert) #The exact nature of this line varies. See below.
with open("to.json", "w") as to:
    json.dump(to, destination)

This uses python's json module, which allows us to do this very easily.

We open the two files for reading, then open the destination file again in writing mode to truncate it and write to it.

The marked line depends on the JSON data structure, here I am appending it to the root list element (which could not exist), but you may want to place it at a particular dict key, or somesuch.

In the case of replacing the contents, it becomes easier:

with open("from.json", "r") as from, open("to.json", "w") as to:
    to.write(from.read())

Here we literally just read the data out of one file and write it into the other file.

Of course, you may wish to check the data is JSON, in which case, you can use the JSON methods as in the first solution, which will throw exceptions on invalid data.

Another, arguably better, solution to this could also be shutil's copy methods, which would avoid actually reading or writing the file contents manually.

Using the with statement gives us the benefit of automatically closing our files - even if exceptions occur. It's best to always use them where we can.

Note that in versions of Python before 2.7, multiple context managers are not handled by the with statement, instead you will need to nest them:

with open("from.json", "r") as from:
    with open("to.json", "r+") as to:
        ...

Upvotes: 6

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