The JSON object must be str, bytes or bytearray, not list

The JSON object must be str, bytes or bytearray, not list #

The Python "TypeError: the JSON object must be str, bytes or bytearray, not list" occurs when we pass a list to the json.loads() method. To solve the error, remove the call to json.loads() and use the json.dumps() method if trying to convert the list to a JSON string.

Here is an example of how the error occurs.

Copied!
import json


my_list = ['Alice', 'Bob', 'Carl']

# ⛔️ TypeError: the JSON object must be str, bytes or bytearray, not list
result = json.loads(my_list)

The json.loads method parses a JSON string into a native Python object.

If you need to convert a list to a JSON string, use the json.dumps() method.

Copied!
import json


my_list = ['Alice', 'Bob', 'Carl']

my_json_str = json.dumps(my_list)

print(my_json_str)  # 👉️ '["Alice", "Bob", "Carl"]'
print(type(my_json_str))  # 👉️ <class 'str'>

The json.dumps method converts a Python object to a JSON formatted string.

In other words, if you need to parse a JSON string into a native Python object, you have to use the json.loads() method, and if you need to convert a Python object into a JSON string, you have to use the json.dumps() method.

Copied!
import json


json_str = r'["Alice", "Bob", "Carl"]'

my_list = json.loads(json_str)
print(type(my_list))  # 👉️ <class 'list'>


my_json_str = json.dumps(my_list)
print(type(my_json_str))  # 👉️ <class 'str'>

The json.loads() method basically helps us load a Python native object (e.g. a list or a dictionary) from a JSON string.

If you need to read from a json file, use the json.load() method.

Copied!
import json


file_name = 'example.json'

with open(file_name, 'r', encoding='utf-8') as f:
    my_data = json.load(f)

    print(my_data)  # 👉️ ['Alice', 'Bob', 'Carl']
    print(my_data[0])  # 👉️ 'Alice'
    print(type(my_data))  # 👉️ <class 'list'>

The code sample above assumes that you have an example.json file in the same directory.

Copied!
["Alice", "Bob", "Carl"]

The json.load method is used to deserialize a file to a Python object, whereas the json.loads method is used to deserialize a JSON string to a Python object.

The json.load() method expects a text file or a binary file containing a JSON document that implements a .read() method.

The JSONEncoder class supports the following objects and types by default.

If you aren't sure what type of object a variable stores, use the built-in type() class.

Copied!
my_list = ['a', 'b', 'c']

print(type(my_list))  # 👉️ <class 'list'>
print(isinstance(my_list, list))  # 👉️ True

my_str = 'hello'

print(type(my_str))  # 👉️ <class 'str'>
print(isinstance(my_str, str))  # 👉️ True

The type class returns the type of an object.

The isinstance function returns True if the passed in object is an instance or a subclass of the passed in class.

Conclusion #

The Python "TypeError: the JSON object must be str, bytes or bytearray, not list" occurs when we pass a list to the json.loads() method. To solve the error, remove the call to json.loads() and use the json.dumps() method if trying to convert the list to a JSON string.