How to Convert a Dictionary to a String in Python

To convert a dict to a string in Python, use json.dumps(d) when the text will be stored, sent to an API or read by another program, and str(d) for a quick, Python-style text you only want to print or log. For a custom format such as key=value pairs, join the items yourself. This guide compares these ways to convert a Python dictionary to a string, shows the formatting options, the two errors people hit most often, and how to turn the string back into a dict.

All examples were run with Python 3.12.5 in the Windows Command Prompt. Reference: json.dumps() and ast.literal_eval() in the Python docs.

str() vs json.dumps()

import json

order = {"id": 1042, "customer": "Anna", "paid": True, "items": ["pen", "notebook"]}

text1 = str(order)            # Python syntax: single quotes, True
text2 = json.dumps(order)     # JSON: double quotes, true

print(text1, type(text1))
print(text2, type(text2))

Output:

{'id': 1042, 'customer': 'Anna', 'paid': True, 'items': ['pen', 'notebook']} <class 'str'>
{"id": 1042, "customer": "Anna", "paid": true, "items": ["pen", "notebook"]} <class 'str'>

	str(d)	json.dumps(d)
Quotes	Single quotes	Double quotes
True / None	True, None	true, null
Valid JSON?	No	Yes
Works for any value?	Yes	Only JSON types (unless you pass default=)
Convert back with	ast.literal_eval()	json.loads()
Use for	Printing, logging, debugging	Files, APIs, databases, other languages

json.dumps() formatting options

import json

user = {"name": "José", "city": "São Paulo", "age": 31, "tags": ["admin", "beta"]}

print(json.dumps(user))                                   # non-ASCII escaped by default
print(json.dumps(user, ensure_ascii=False))               # keep the real characters
print(json.dumps(user, sort_keys=True, separators=(",", ":")))   # compact and ordered
print(json.dumps(user, indent=2, ensure_ascii=False))     # pretty, multi-line

Output:

{"name": "Jos\u00e9", "city": "S\u00e3o Paulo", "age": 31, "tags": ["admin", "beta"]}
{"name": "José", "city": "São Paulo", "age": 31, "tags": ["admin", "beta"]}
{"age":31,"city":"S\u00e3o Paulo","name":"Jos\u00e9","tags":["admin","beta"]}
{
  "name": "José",
  "city": "São Paulo",
  "age": 31,
  "tags": [
    "admin",
    "beta"
  ]
}

• indent=2 produces readable multi-line JSON.
• ensure_ascii=False keeps characters like é and ã instead of \u00e9 escapes.
• sort_keys=True gives the same string for equal dictionaries, which helps when comparing or caching.
• separators=(",", ":") removes spaces for the smallest output.

TypeError: Object of type … is not JSON serializable

json.dumps() only understands dicts, lists, strings, numbers, booleans and None. Dates, Decimal, sets and your own classes raise a TypeError. Pass a default function that converts them:

import json
from datetime import date
from decimal import Decimal

invoice = {"number": "INV-7", "date": date(2025, 7, 4), "total": Decimal("149.90")}

try:
    json.dumps(invoice)
except TypeError as e:
    print("TypeError:", e)

print(json.dumps(invoice, default=str))      # convert anything unknown with str()
print(str(invoice))                           # str() always works, but it is not JSON

Output:

TypeError: Object of type date is not JSON serializable
{"number": "INV-7", "date": "2025-07-04", "total": "149.90"}
{'number': 'INV-7', 'date': datetime.date(2025, 7, 4), 'total': Decimal('149.90')}

Custom formats: key=value, keys only, values only

from urllib.parse import urlencode

settings = {"theme": "dark", "font_size": 14, "autosave": True}

print(", ".join(f"{k}={v}" for k, v in settings.items()))     # key=value pairs
print("; ".join(f"{k}: {v}" for k, v in settings.items()))    # any format you like
print(urlencode(settings))                                     # a URL query string
print(", ".join(settings))                                     # only the keys
print(", ".join(map(str, settings.values())))                  # only the values

Output:

theme=dark, font_size=14, autosave=True
theme: dark; font_size: 14; autosave: True
theme=dark&font_size=14&autosave=True
theme, font_size, autosave
dark, 14, True

TypeError: sequence item 0: expected str instance

str.join() only joins strings, so joining numbers fails until you convert them:

scores = {"Anna": 91, "Ben": 78}

try:
    print(", ".join(scores.values()))            # the values are ints
except TypeError as e:
    print("TypeError:", e)

print(", ".join(str(v) for v in scores.values()))   # convert each value first

Output:

TypeError: sequence item 0: expected str instance, int found
91, 78

Convert the string back to a dictionary

Use the reverse of the function you used to create the string. Never use eval() on text you did not write, because it runs any code inside it:

import ast
import json

d = {"id": 7, "ok": True, "note": None}

s_json = json.dumps(d)
s_str = str(d)
print(json.loads(s_json) == d)            # JSON text -> dict
print(ast.literal_eval(s_str) == d)       # str() text -> dict, safely

try:
    json.loads(s_str)                     # str() output is NOT valid JSON
except json.JSONDecodeError as e:
    print("JSONDecodeError:", e)

Output:

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

More on this direction: convert a string to a dictionary in Python.

Nested dictionaries as a readable string

pprint.pformat() returns the same nicely wrapped text that pprint() prints:

from pprint import pformat

config = {"database": {"host": "db.example.com", "port": 5432, "options": {"ssl": True, "timeout": 30}},
          "features": ["search", "export", "sharing"], "debug": False}

text = pformat(config, width=60)          # a readable multi-line string
print(text)

Output:

{'database': {'host': 'db.example.com',
              'options': {'ssl': True, 'timeout': 30},
              'port': 5432},
 'debug': False,
 'features': ['search', 'export', 'sharing']}

Related dictionary and conversion tutorials:

• Convert a string to a dictionary in Python
• Convert a dictionary to JSON in Python
• Initialize a dictionary in Python
• Convert a string to float in Python

Frequently asked questions