74-Get Query Parameter Value.md

Utility 74: Get Query Parameter Value

What It Does

Retrieves the value of a key in a query string. If the key appears multiple times, it returns a list. If it appears once, it returns a single value.

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Code Example

from urllib.parse import parse_qs

def get_query_param(qs, key, default=None):
    parsed = parse_qs(qs)

    if key not in parsed:
        return default

    values = parsed[key]

    # Convert single-value lists to a plain value
    return values[0] if len(values) == 1 else values

# Example
qs = "page=1&sort=asc&tag=python&tag=testing"
print(get_query_param(qs, "page"))   # '1'
print(get_query_param(qs, "tag"))    # ['python', 'testing']
print(get_query_param(qs, "filter", "none"))  # 'none'

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Notes

• Returns plain values whenever possible.
• Gracefully handles multi-value parameters.
• Provides an optional default.

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Next Step

Utility 75: Replace entire query string on a URL (preserve path + scheme).