如何将多行JSON字符串作为参数传入Python脚本？

When you need to feed a nicely formatted, multi-line JSON into a Python script, there are several practical approaches depending on your use case and shell environment. Here are the most reliable methods to get the job done:

1. Read JSON from Standard Input (stdin) #

This is a clean, pipe-friendly approach—perfect if you want to either write the JSON inline or pipe it from an existing source.

Python Script Example (script.py): #

import sys
import json

def main():
    try:
        # Read and parse JSON directly from stdin
        data = json.load(sys.stdin)
        print("Successfully parsed JSON:")
        print(json.dumps(data, indent=2))
    except json.JSONDecodeError as e:
        print(f"Oops, invalid JSON: {e}")

if __name__ == "__main__":
    main()

Running the Script: #

Using a Here-Document (Bash/Zsh):

Write your JSON directly in the command line without a separate file:

python script.py << EOF
{
  "name": "Alice",
  "age": 30,
  "hobbies": ["reading", "hiking", "coding"],
  "address": {
    "street": "123 Main St",
    "city": "Anytown"
  }
}
EOF

Piping from a File:

If your JSON is already saved to a file (like data.json), pipe it into the script:

cat data.json | python script.py

2. Pass JSON as a Quoted Command-Line Argument #

For small JSON snippets, you can wrap the multi-line JSON in quotes and pass it as a positional argument. Just be mindful of shell escaping rules.

Python Script Example (script.py): #

import sys
import json

def main():
    if len(sys.argv) < 2:
        print("Usage: python script.py '<your-JSON>'")
        return
    
    try:
        data = json.loads(sys.argv[1])
        print("Successfully parsed JSON:")
        print(json.dumps(data, indent=2))
    except json.JSONDecodeError as e:
        print(f"Invalid JSON: {e}")

if __name__ == "__main__":
    main()

Running the Script: #

In Bash/Zsh:

Use single quotes to preserve line breaks and formatting (avoid single quotes inside your JSON, or escape them with '\''):

python script.py '{
  "name": "Bob",
  "age": 25,
  "is_student": true
}'

In PowerShell:

Use a here-string for clean multi-line input:

python script.py @"
{
  "name": "Charlie",
  "age": 35,
  "email": "charlie@example.com"
}
"@

Note: This method works best for short JSON. For large or complex structures, stick to the file method below to avoid escaping headaches.

3. Read JSON from a File (Most Reliable for Large JSON) #

Storing your formatted JSON in a separate file and passing the file path as an argument is the most straightforward and error-proof method, especially for big datasets.

Python Script Example (script.py): #

import sys
import json

def main():
    if len(sys.argv) < 2:
        print("Usage: python script.py <path-to-json-file>")
        return
    
    file_path = sys.argv[1]
    try:
        with open(file_path, 'r') as f:
            data = json.load(f)
        print("Successfully parsed JSON:")
        print(json.dumps(data, indent=2))
    except FileNotFoundError:
        print(f"Error: File '{file_path}' doesn't exist.")
    except json.JSONDecodeError as e:
        print(f"Invalid JSON in file: {e}")

if __name__ == "__main__":
    main()

Running the Script: #

Save your JSON to data.json:

{
  "products": [
    {"id": 1, "name": "Laptop", "price": 999.99},
    {"id": 2, "name": "Phone", "price": 699.99}
  ],
  "store": "TechMart"
}

Then run:

python script.py data.json

4. Pass JSON via Environment Variable #

If you need to pass JSON alongside other command-line arguments, storing it in an environment variable is a handy option.

Python Script Example (script.py): #

import os
import json

def main():
    json_data = os.environ.get('MY_JSON')
    if not json_data:
        print("Error: Set the MY_JSON environment variable first.")
        return
    
    try:
        data = json.loads(json_data)
        print("Successfully parsed JSON:")
        print(json.dumps(data, indent=2))
    except json.JSONDecodeError as e:
        print(f"Invalid JSON: {e}")

if __name__ == "__main__":
    main()

Running the Script (Bash/Zsh): #

Export the JSON as an environment variable (use single quotes to keep formatting intact):

export MY_JSON='{
  "user": "dave",
  "permissions": ["read", "write"],
  "active": true
}'
python script.py

内容的提问来源于stack exchange，提问作者Abdul Jaleel