How to parse key=value pairs in Python

Parse a single line of key=value pairs separated by a delimiter into a Python dictionary.

Easy Python 3.9+ Aug 9, 2026 Strings & text 11 views 0 copies

parsing key-value dictionary text-processing

Python code

15 lines

Python 3.9+

def parse_key_value_pairs(line: str, delimiter: str = "&") -> dict:
    """Parse a single line of key=value pairs into a dictionary."""
    pairs = {}
    for token in line.split(delimiter):
        if not token.strip():
            continue
        key, _, value = token.partition("=")
        pairs[key.strip()] = value.strip()
    return pairs


if __name__ == "__main__":
    line = "name=Alice&age=30&city=New York&active=true"
    result = parse_key_value_pairs(line)
    print(result)

Output

stdout

{'name': 'Alice', 'age': '30', 'city': 'New York', 'active': 'true'}

How it works

The split(delimiter) call breaks the input line into individual tokens. Each token is processed with partition("="), which splits the string into the key, the separator, and the value. Using partition instead of split is safer because it handles values that may contain the '=' character. The strip() calls clean up any whitespace around keys and values. Empty tokens are skipped with the continue statement.

Common mistakes

Using `split('=')` instead of `partition('=')` breaks values that contain '=' characters
Forgetting to skip empty tokens produces empty string values in the result
Not stripping whitespace leaves unexpected spaces in keys or values

Variations

Use `urlparse` from the `urllib.parse` module if the input is part of a URL query string
Use a dictionary comprehension with a conditional to filter empty tokens

Real-world use cases

Parsing query parameters from a URL string in a web handler before processing the request.
Reading configuration lines from a properties-style file where each line defines one setting.
Converting HTTP form-urlencoded body payloads into a structured dictionary for validation.

How to parse key=value pairs in Python

Python code

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How it works

Common mistakes

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