jsonplate

jsonplate is a lightweight, standards-compliant JSON templating engine for Python. It enables dynamic generation of JSON by allowing parameter substitution in values, keys, and strings.

🔧 Features

• ✅ Spec-compliant JSON parser
• 🧩 Parameter substitution in:
  • Object keys
  • Object or array values
  • String literals via {{variable}} syntax
• 🧱 Reusable templates via load_template
• 🔍 Variable introspection via variable_names
• 🚫 No logic blocks, loops, or control flow

📦 Installation

Install via PyPI:

pip install jsonplate

🚀 Usage

Simple Usage

import jsonplate

template = '''
{
    "{{greeting_key}}": "Hello, {{name}}!",
    "values": [1, 2, 3, param_value],
    "config": {
        "enabled": true,
        param_key: 123
    }
}
'''

result = jsonplate.parse(
    template,
    greeting_key="message",
    name="Alice",
    param_value=42,
    param_key="threshold"
)

print(result)

Output:

{
    "message": "Hello, Alice!",
    "values": [1, 2, 3, 42],
    "config": {
        "enabled": true,
        "threshold": 123
    }
}

Reusable Templates

You can parse once and render multiple times with different parameters:

template = jsonplate.load_template('{"user": "{{name}}"}')

template(name="Alice")  # {"user": "Alice"}
template(name="Bob")    # {"user": "Bob"}

⚠️ Errors

All parsing and templating errors inherit from the base jsonplate.errors.JSONError class.

You may specifically catch:

• JSONTemplaterError: raised when template substitution fails

• JSONParserError: raised when a syntax violation is encountered

• JSONLexerError: raised when tokenization fails