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Scaffolding Commands

Code generation commands for creating custom validators, reporters, and plugins.

Overview

Command Description Primary Use Case
new validator Create custom validator Validation logic
new reporter Create custom reporter Output formatting
new plugin Create plugin package Extension development
new list List scaffold types Discovery
new templates List templates Template selection

What is Scaffolding?

Scaffolding generates boilerplate code for extending Truthound:

  • Validators - Custom data quality checks
  • Reporters - Custom output formats
  • Plugins - Packaged extensions with multiple components

Quick Examples

Create a Validator

# Basic validator
truthound new validator my_validator

# Pattern validator with regex
truthound new validator email_format --template pattern --pattern "^[a-z@.]+$"

# Range validator
truthound new validator percentage --template range --min 0 --max 100

Create a Reporter

# Basic reporter
truthound new reporter my_reporter

# JSON reporter
truthound new reporter json_export --extension .json --content-type application/json

Create a Plugin

# Validator plugin
truthound new plugin my_validators --type validator

# Full plugin with all components
truthound new plugin enterprise --type full

Discover Options

# List available scaffolds
truthound new list --verbose

# List validator templates
truthound new templates validator

Workflow

graph LR
    A[new list] --> B[Choose Type]
    B --> C[new templates]
    C --> D[Choose Template]
    D --> E[new validator/reporter/plugin]
    E --> F[Generated Code]
    F --> G[Customize]
    G --> H[Test & Use]

Generated Structure

Validator

my_validator/
├── __init__.py
├── my_validator.py      # Validator implementation
└── tests/
    └── test_my_validator.py

Reporter

my_reporter/
├── __init__.py
├── my_reporter.py       # Reporter implementation
└── tests/
    └── test_my_reporter.py

Plugin

my_plugin/
├── pyproject.toml       # Package configuration
├── README.md
├── src/
│   └── my_plugin/
│       ├── __init__.py
│       ├── validators/  # (if type=validator)
│       ├── reporters/   # (if type=reporter)
│       └── hooks/       # (if type=hook)
└── tests/

Common Options

Option Description Available In
--output, -o Output directory All
--author, -a Author name All
--description, -d Description All
--tests/--no-tests Generate tests All
--docs/--no-docs Generate docs validator, reporter

Use Cases

1. Custom Validation Logic

# Create validator for business rules
truthound new validator customer_age \
  --template range \
  --min 18 \
  --max 120 \
  --description "Validate customer age range"

2. Custom Output Format

# Create XML reporter
truthound new reporter xml_export \
  --template full \
  --extension .xml \
  --content-type application/xml

3. Reusable Plugin Package

# Create distributable plugin
truthound new plugin company_validators \
  --type validator \
  --author "Data Team" \
  --min-version 1.0.0

4. Integration Development

# Create datasource connector
truthound new plugin custom_db \
  --type datasource \
  --description "Custom database connector"

Command Reference

See Also

Generated Python and package metadata preserve quotes, backslashes and newlines in descriptions and author names. Component names must be importable identifiers and cannot be Python keywords. Plugin packages require Python 3.11 or newer; lower or malformed --python versions fail before any files are emitted. The generated tests and examples use the current Core contracts.

Scaffolds reject unknown severity values, nonfinite/reversed range bounds, invalid or unsupported regexes, malformed column lists and options used with incompatible templates before emitting files. Reporter extensions must be filename suffixes and content types cannot contain control characters. Generated reporters honor include_passed=True and max_issues=0.