json2v

JSON → V struct generator (enhanced)

A CLI tool that reads JSON and emits ready‑to‑compile V struct definitions.
Built‑in lint checks catch naming issues, reserved words, type conflicts and more, while --fix can automatically repair many common problems.

Features

• Smart type inference – list element types, null/optional types, nested structs
• Lint diagnostics – naming conventions, reserved words, duplicate fields, type conflicts
• Auto‑fix – camelCase → snake_case, reserved word escaping, null‑type suggestions
• Colored terminal output, verbose & dry‑run modes, and strict‑mode error handling
• Reads from stdin or file; writes to stdout or file

Installation

Requirements

• Python 3.8 or higher (no external dependencies)

Recommended: install as a system command

Create a setup.py file in the same directory as json2v.py:

from setuptools import setup

setup(
    name='json2v',
    version='2.1',
    py_modules=['json2v'],
    entry_points={
        'console_scripts': ['json2v=json2v:main'],
    },
    python_requires='>=3.8',
)

Then install with pip:

pip install .

Now you can invoke the tool globally:

json2v -i data.json -o output.v

Alternative: manual placement

Make the script executable and move it into your PATH:

chmod +x json2v.py
sudo cp json2v.py /usr/local/bin/json2v

After that, json2v works from any terminal.

Quick start

# From stdin
echo '{"name":"Alice","age":30}' | json2v

# From a file, output to another file
json2v -i data.json -o output.v

# Lint + auto‑fix with verbose diagnostics
json2v -i data.json --lint --fix -v

Options

Flag	Default	Description
-i, --input FILE	stdin	Input JSON file
-o, --output FILE	stdout	Output V file
--root NAME	Root	Root struct name
--lint	off	Enable lint diagnostics
--fix	off	Auto‑fix lint issues (implies --lint)
--dry-run	off	Only lint, no code output (implies --lint)
-v, --verbose	off	Show detailed diagnostics and suggestions
--no-color	off	Disable colored terminal output
--strict	off	Treat warnings as errors; exit code 1 on any warning
--version		Show version

Lint diagnostic codes

Code	Severity	Description
V001	Warning	Empty list – cannot infer element type
V002	Warning	List contains mixed element types
V003	Warning	Field value is null – cannot determine concrete type
V004	Error	Value type cannot be mapped to a V type
V010	Error/Warning	Field name is a V reserved word
V011	Error/Warning	Field name conflicts with a built‑in V type
V012	Warning	Field name is not snake_case
V013	Error/Warning	Field name starts with a digit
V014	Error	Name collision after auto‑fix
V020	Error	JSON root is not an object

Example

Input (data.json)

{
  "userName": "Alice",
  "userAge": 30,
  "isActive": true,
  "metadata": {
    "lastLogin": "2026-05-01",
    "score": 42.5
  },
  "tags": ["admin", "moderator"],
  "profile": null,
  "items": [
    {"id": 1, "value": "one"},
    {"id": 2, "value": "two"}
  ]
}

Command

json2v -i data.json --lint --fix -v

Generated V code (stdout)

import json

pub struct Root {
    [json: userName]
    mut user_name string
    [json: userAge]
    mut user_age int
    [json: isActive]
    mut is_active bool
    [json: metadata]
    mut metadata struct {
        [json: lastLogin]
        mut last_login string
        [json: score]
        mut score f64
    }
    [json: tags]
    mut tags []string
    [json: profile]
    mut profile ?any
    [json: items]
    mut items []Item
}

pub struct Item {
    [json: id]
    mut id int
    [json: value]
    mut value string
}

Lint report (stderr, with -v)

══════════════════════════════════════════════════════
  Lint Report
══════════════════════════════════════════════════════

  ⚠ Warnings (2)
    [V012] 'Root.userName' invalid naming
      Path: Root.userName
      Fix: -> user_name
    [V003] Null at 'Root.profile'
      Path: Root.profile
      Fix: Replace ?any

  Total: 2 warning(s)
══════════════════════════════════════════════════════

License

MIT – see LICENSE.