(JSON) TypeError: a bytes-like object is required, not 'str'

(JSON) TypeError: a bytes-like object is required, not 'str' #

To solve the Python JSON "TypeError: a bytes-like object is required, not 'str'", make sure to open the JSON file in w mode and not wb mode when writing strings to a file.

Here is an example of how the error occurs.

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import json

my_json = json.dumps({'name': 'Alice', 'age': 30})

file_name = 'example.json'

# 👇️ opened file in wb mode
with open(file_name, 'wb') as f:
    # ⛔️ TypeError: a bytes-like object is required, not 'str'
    f.write(my_json)

We opened the file in wb (binary) mode rather than w (text) mode which caused the error.

To solve the error, use the w mode when writing to a JSON file.

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import json

my_json = json.dumps({'name': 'Alice', 'age': 30})

file_name = 'example.json'

# ✅ opened file in w mode and set encoding to utf-8
with open(file_name, 'w', encoding='utf-8') as f:
    f.write(my_json)

We opened the JSON file in w (text) mode.

When a file is opened in text mode, we read and write strings from and to the file.

Those strings are encoded using a specific encoding (utf-8 in the example).

If you want to both read from and write to the file, use the r+ mode when opening it.

Note that you cannot specify encoding when opening a file in binary mode.

When a file is opened in binary mode, data is read and written as bytes objects.

This means that you could encode your JSON string to a bytes object using the encode() method if you have the wb mode set.

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import json

my_json = json.dumps({'name': 'Alice', 'age': 30})

file_name = 'example.json'

with open(file_name, 'wb') as f:
    f.write(my_json.encode('utf-8'))

The str.encode method returns an encoded version of the string as a bytes object. The default encoding is utf-8.

However, it is much simpler to open the JSON file in w (or another text) mode, so you can write strings directly.