JSONDecodeError: Expecting property name enclosed in double quotes: line 1 column 2 (char 1)

# JSONDecodeError: Expecting property name enclosed in double quotes: line 1 column 2 (char 1)

The Python "JSONDecodeError: Expecting property name enclosed in double quotes: line 1 column 2 (char 1)" occurs when we try to parse an invalid JSON string (e.g. single-quoted keys or values, or a trailing comma).

Use the ast.literal_eval() method to solve the error.

Here is an example of how the error occurs.

main.py

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import json

invalid_json = r"{'name': 'Bobby'}" # 👈️ single-quoted

# ⛔️ json.decoder.JSONDecodeError: Expecting property name enclosed in double quotes: line 1 column 2 (char 1)
result = json.loads(invalid_json)

single quoted property

Notice that the string has a single-quoted key and value, which means that it isn't a valid JSON string.

Rather, it's just a Python dictionary that's wrapped in a string.

JSON (string) keys and values must be enclosed in double quotes.

main.py

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import json

# ✅ Valid JSON string
valid_json = r'{"name": "Bobby Hadz", "age": 30}' # 👈️ no trailing comma

a_dict = json.loads(valid_json)
print(a_dict) # {'name': 'Bobby Hadz', 'age': 30}

valid json string

The example string above is valid JSON because the properties and values are double-quoted and there is no trailing comma.

# Using the `ast.literal_eval` method to evaluate the string

You can solve the error by using the ast.literal_eval method to evaluate the string that contains a Python literal.

main.py

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import ast

invalid_json = r"{'name': 'Bobby Hadz'}"

result = ast.literal_eval(invalid_json)
print(type(result))  # 👉️ <class 'dict'>

print(result)  # 👉️ {'name': 'Bobby Hadz'}
print(result['name'])  # 👉️ Bobby Hadz

using ast literal eval to evaluate the string

The ast.literal_eval() method allows us to safely evaluate a string that contains a Python literal.

The string may consist of strings, bytes, numbers, tuples, lists, dicts, sets, booleans and None.

# Converting a Python dictionary to JSON

If you are trying to convert a Python dictionary to a JSON string, use the json.dumps() method.

main.py

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import json


my_dict = {
    'id': 1,
    'name': 'Bobby Hadz',
    'age': 30,
}

json_str = json.dumps(my_dict)

print(json_str) # {"id": 1, "name": "Bobby Hadz", "age": 30}
print(type(json_str)) # <class 'str'>

convert python dictionary to json

Notice that we didn't wrap the my_dict variable in single or double quotes to declare a dictionary.

If you wrap the variable in quotes, you end up declaring a string.

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

# Using the `str.replace` method to replace single with double quotes

An alternative approach is to use the str.replace() method to replace all single quotes in the string with double quotes.

main.py

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import json

invalid_json = r"{'name': 'Alice'}"

valid_json = invalid_json.replace("\'", "\"")
print(valid_json)  # 👉️ '{"name": "Alice"}'

my_dict = json.loads(valid_json)

print(my_dict)  # 👉️ {'name': 'Alice'}
print(type(my_dict))  # 👉️ <class 'dict'>

replace single with double quotes

The str.replace() method returns a copy of the string with all occurrences of a substring replaced by the provided replacement.

The method takes the following parameters:

Name	Description
old	The substring we want to replace in the string
new	The replacement for each occurrence of `old`
count	Only the first `count` occurrences are replaced (optional)

main.py

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a_str = "'one', 'two', 'three'"

result = a_str.replace("'", '"')
print(result) # "one", "two", "three"

However, this is very risky because the string could contain a single quote somewhere in its content, e.g. It's her.

# Using `ast.literal_eval` to deal with trailing commas

You can also use the ast.literal_eval method if your string contains a trailing comma.

main.py

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import ast

invalid_json = r'{"name": "Bobby Hadz",}' # 👈️ has trailing comma

result = ast.literal_eval(invalid_json)
print(type(result))  # 👉️ <class 'dict'>

print(result)  # 👉️ {'name': 'Bobby Hadz'}
print(result['name'])  # 👉️ Bobby Hadz

The trailing comma also makes the string invalid JSON, but Python dictionaries are allowed to have a trailing comma after the last key-value pair.

# Using the PyYAML module to parse the string

Alternatively, you can try using the yaml.safe_load() method.

Make sure you have pyyaml installed by running pip install pyyaml.

shell

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pip install pyyaml
pip3 install pyyaml

Now you can import and use the module to parse the JSON string.

main.py

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import yaml

invalid_json = r'{"name": "Alice",}' # 👈️ has trailing comma

my_dict = yaml.safe_load(invalid_json)

print(my_dict)  # 👉️ {'name': 'Alice'}
print(type(my_dict))  # 👉️ <class 'dict'>

Make sure the value you are trying to parse is a JSON string and has not been already parsed into a native Python object.

# Using `str.replace()` method to remove trailing commas

You can also use the str.replace() method to remove the trailing commas from a string.

main.py

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import json


invalid_json = r'{"name": "Bobby Hadz",}'  # 👈️ has trailing comma

valid_json = invalid_json.replace(
    ',}', '}').replace(',]', ']').replace(',)', ')')

print(valid_json) # {"name": "Bobby Hadz"}

a_dict = json.loads(valid_json)
print(a_dict)  # {'name': 'Bobby Hadz'}

We chained 3 calls to the str.replace() method.

The first call removes trailing commas right before a curly brace.

The second call removes trailing commas right before a square bracket.

And the third call removes trailing commas right before a parenthesis.

# Valid JSON vs invalid JSON

Here are some examples of valid and invalid JSON strings.

main.py

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# ⛔️ invalid JSON (has single-quoted keys and values)
invalid_json = r"{'name': 'Alice', 'age': 30, 'tasks' ['a', 'b', 'c']}"

# ✅ valid JSON (double-quoted keys and values)
valid_json = r'{"name": "Alice", "age": 30, "tasks": ["a", "b", "c"]}'

Make sure you don't have a trailing comma after the last element.

main.py

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# ⛔️ invalid JSON (has a trailing comma after the last key-value pair)
invalid_json = r'{"name": "Alice", "age": 30,}'

# ✅ valid JSON (has no trailing comma after the last key-value pair)
valid_json = r'{"name": "Alice", "age": 30}'

# Converting a Python object to a JSON string and vice versa

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.

main.py

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import json

json_str = r'{"name": "Alice", "age": 30}'


# ✅ parse JSON string to Python native dict
my_dict = json.loads(json_str)
print(type(my_dict))  # 👉️ <class 'dict'>

# ✅ convert Python native dict to a JSON string
my_json_str = json.dumps(my_dict)
print(type(my_json_str))  # 👉️ <class 'str'>

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

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

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

Python	JSON
dict	object
list, tuple	array
str	string
int, float, int and float derived Enums	number
True	true
False	false
None	null

# Validating your JSON strings

You can paste your code into an online Syntax Validator . The validator should be able to tell you on which line the error occurred.

You can hover over the squiggly red line to get additional information on why the error was thrown.

# Checking what type a variable stores

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

main.py

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my_dict = {'name': 'Alice', 'age': 30}
print(type(my_dict))  # 👉️ <class 'dict'>
print(isinstance(my_dict, dict))  # 👉️ True


my_str = 'hello world'
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.

# Additional Resources

You can learn more about the related topics by checking out the following tutorials:

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JSONDecodeError: Expecting property name enclosed in double quotes: line 1 column 2 (char 1)