Value Transformers

Value transformers allow you to transform prompt and variable values before they’re used in your configurations. This enables powerful data manipulation and validation workflows.

Overview
Built-in Transformers
Transformer Types
Using Transformers
Transformer Chains
Custom Transformers
Examples

Overview

Transformers are applied to:

Prompts: Transform user input before storing in variables
Variables: Transform computed values before using in configurations
Global Transformers: Define custom transformers for reuse across your configuration

Key Features

Built-in transformers for common string operations (case conversion, formatting, cleaning)
Regex transformers for pattern-based replacements
Computed transformers for JavaScript expressions
Chain transformers to apply multiple transformations sequentially
Custom transformers defined globally and reused throughout your configuration

Built-in Transformers

Scaffoldfy provides these built-in transformers:

`lowercase`

Converts the value to lowercase.

{
  "id": "email",
  "message": "Enter your email",
  "type": "input",
  "transformers": ["lowercase"]
}

`uppercase`

Converts the value to uppercase.

{
  "id": "constantName",
  "message": "Enter constant name",
  "type": "input",
  "transformers": ["uppercase"]
}

`trim`

Removes leading and trailing whitespace.

{
  "id": "username",
  "message": "Enter username",
  "type": "input",
  "transformers": ["trim"]
}

`slugify`

Converts a string to a URL-friendly slug (lowercase, spaces to hyphens, special chars removed).

{
  "id": "projectName",
  "message": "Enter project name",
  "type": "input",
  "transformers": ["slugify"]
}

Example:

Input: "My Awesome Project!"
Output: "my-awesome-project"

`capitalize`

Capitalizes the first letter of the string.

{
  "id": "title",
  "message": "Enter title",
  "type": "input",
  "transformers": ["capitalize"]
}

Example:

Input: "hello world"
Output: "Hello world"

`titlecase`

Converts the string to title case (capitalizes the first letter of each word with spaces). This transformer properly handles all input formats (camelCase, kebab-case, snake_case, etc.) and converts them to a properly formatted title.

{
  "id": "headline",
  "message": "Enter headline",
  "type": "input",
  "transformers": ["titlecase"]
}

Examples:

Input: "hello world example" → Output: "Hello World Example"
Input: "fooBar" → Output: "Foo Bar"
Input: "foo-bar-baz" → Output: "Foo Bar Baz"
Input: "foo_bar" → Output: "Foo Bar"
Input: "FooBarBaz" → Output: "Foo Bar Baz"

This is the recommended transformer when you want to convert any format to a human-readable title with proper capitalization and spacing.

`capitalCase`

Converts the string to capital case (capitalizes the first letter of each word).

{
  "id": "headline",
  "message": "Enter headline",
  "type": "input",
  "transformers": ["capitalCase"]
}

Example:

Input: "hello world example"
Output: "Hello World Example"

`camelcase`

Converts the string to camelCase.

{
  "id": "variableName",
  "message": "Enter variable name",
  "type": "input",
  "transformers": ["camelcase"]
}

Example:

Input: "hello world example"
Output: "helloWorldExample"

`pascalcase`

Converts the string to PascalCase.

{
  "id": "className",
  "message": "Enter class name",
  "type": "input",
  "transformers": ["pascalcase"]
}

Example:

Input: "hello world example"
Output: "HelloWorldExample"

`snakecase`

Converts the string to snake_case.

{
  "id": "fileName",
  "message": "Enter file name",
  "type": "input",
  "transformers": ["snakecase"]
}

Example:

Input: "Hello World Example"
Output: "hello_world_example"

`kebabcase`

Converts the string to kebab-case.

{
  "id": "cssClass",
  "message": "Enter CSS class",
  "type": "input",
  "transformers": ["kebabcase"]
}

Example:

Input: "Hello World Example"
Output: "hello-world-example"

`constantcase`

Converts the string to CONSTANT_CASE.

{
  "id": "envVar",
  "message": "Enter environment variable",
  "type": "input",
  "transformers": ["constantcase"]
}

Example:

Input: "hello world example"
Output: "HELLO_WORLD_EXAMPLE"

`alphanumeric`

Removes all non-alphanumeric characters from the string.

{
  "id": "cleanId",
  "message": "Enter identifier",
  "type": "input",
  "transformers": ["alphanumeric"]
}

Example:

Input: "Hello@World#123!"
Output: "HelloWorld123"

`collapse-spaces`

Collapses multiple consecutive spaces into a single space.

{
  "id": "description",
  "message": "Enter description",
  "type": "input",
  "transformers": ["collapse-spaces"]
}

Example:

Input: "Hello World Example"
Output: "Hello World Example"

`remove-spaces`

Removes all spaces from the string.

{
  "id": "compactName",
  "message": "Enter compact name",
  "type": "input",
  "transformers": ["remove-spaces"]
}

Example:

Input: "Hello World Example"
Output: "HelloWorldExample"

`urlencode`

URL-encodes the string.

{
  "id": "encodedUrl",
  "message": "Enter URL",
  "type": "input",
  "transformers": ["urlencode"]
}

Example:

Input: "Hello World"
Output: "Hello%20World"

`dasherize`

Converts the string to dash-separated format (similar to kebab-case but may handle special cases).

{
  "id": "dashedName",
  "message": "Enter dashed name",
  "type": "input",
  "transformers": ["dasherize"]
}

Example:

Input: "HelloWorldExample"
Output: "hello-world-example"

`underscore`

Converts the string to underscore-separated format (similar to snake_case but may handle special cases).

{
  "id": "underscoredName",
  "message": "Enter underscored name",
  "type": "input",
  "transformers": ["underscore"]
}

Example:

Input: "HelloWorldExample"
Output: "hello_world_example"

`adaCase`

Converts the string to Ada_Case format (capitalized words separated by underscores).

{
  "id": "adaName",
  "message": "Enter Ada-style name",
  "type": "input",
  "transformers": ["adaCase"]
}

Example:

Input: "helloWorldExample"
Output: "Hello_World_Example"

`cobolCase`

Converts the string to COBOL-CASE format (uppercase words separated by hyphens).

{
  "id": "cobolName",
  "message": "Enter COBOL-style name",
  "type": "input",
  "transformers": ["cobolCase"]
}

Example:

Input: "helloWorldExample"
Output: "HELLO-WORLD-EXAMPLE"

`dotNotation`

Converts the string to dot.notation format (lowercase words separated by dots).

{
  "id": "propertyPath",
  "message": "Enter property path",
  "type": "input",
  "transformers": ["dotNotation"]
}

Example:

Input: "helloWorldExample"
Output: "hello.World.Example" (note: preserves original casing within segments)

`pathCase`

Converts the string to path/case format (words separated by forward slashes).

{
  "id": "filePath",
  "message": "Enter file path",
  "type": "input",
  "transformers": ["pathCase"]
}

Example:

Input: "helloWorldExample"
Output: "hello/World/Example" (note: preserves original casing within segments)

`spaceCase`

Converts the string to space case format (words separated by spaces, lowercase).

{
  "id": "displayName",
  "message": "Enter display name",
  "type": "input",
  "transformers": ["spaceCase"]
}

Example:

Input: "helloWorldExample"
Output: "hello World Example" (note: may preserve some original casing)

`trainCase`

Converts the string to Train-Case format (capitalized words separated by hyphens).

{
  "id": "trainName",
  "message": "Enter Train-Case name",
  "type": "input",
  "transformers": ["trainCase"]
}

Example:

Input: "helloWorldExample"
Output: "Hello-World-Example"

`upperCamelCase`

Converts the string to UpperCamelCase format (same as PascalCase).

{
  "id": "componentName",
  "message": "Enter component name",
  "type": "input",
  "transformers": ["upperCamelCase"]
}

Example:

Input: "hello-world-example"
Output: "HelloWorldExample"

Transformer Types

Regex Transformer

Apply regular expression find-and-replace operations.

{
  "type": "regex",
  "pattern": "-",
  "replacement": "_",
  "flags": "g"
}

Properties:

pattern (string, required): The regex pattern to match
replacement (string, required): The replacement string
flags (string, optional): Regex flags (e.g., “g” for global, “i” for case-insensitive)

Example:

{
  "id": "snakeCaseName",
  "value": "",
  "transformers": [
    {
      "type": "regex",
      "pattern": "-",
      "replacement": "_",
      "flags": "g"
    }
  ]
}

Computed Transformer

Evaluate a JavaScript expression with access to all context variables.

{
  "type": "computed",
  "expression": "projectName.length"
}

Properties:

expression (string, required): JavaScript expression to evaluate

Example:

{
  "id": "nameLength",
  "value": "computed",
  "transformers": [
    {
      "type": "computed",
      "expression": "projectName.length"
    }
  ]
}

Available Context: All prompts, variables, and environment variables are available in the expression:

{
  "type": "computed",
  "expression": "projectName.toUpperCase() + '_' + version"
}

Using Transformers

On Prompts

Transform user input before storing:

{
  "prompts": [
    {
      "id": "projectName",
      "message": "What is the project name?",
      "type": "input",
      "transformers": ["slugify"]
    },
    {
      "id": "description",
      "message": "Project description",
      "type": "input",
      "transformers": ["trim"]
    }
  ]
}

On Variables

Transform computed variable values:

{
  "variables": [
    {
      "id": "upperProjectName",
      "value": "",
      "transformers": ["uppercase"]
    },
    {
      "id": "packageName",
      "value": "",
      "transformers": [
        "lowercase",
        {
          "type": "regex",
          "pattern": "\\s+",
          "replacement": "-",
          "flags": "g"
        }
      ]
    }
  ]
}

Transformer Chains

Apply multiple transformers in sequence by using an array:

{
  "id": "cleanedName",
  "value": "  My Project  ",
  "transformers": ["trim", "lowercase", "slugify"]
}

Execution Order:

trim → "My Project"
lowercase → "my project"
slugify → "my-project"

Complex Chain Example

{
  "id": "formattedName",
  "value": "",
  "transformers": [
    "trim",
    {
      "type": "regex",
      "pattern": "[^a-zA-Z0-9\\s-]",
      "replacement": "",
      "flags": "g"
    },
    "lowercase",
    {
      "type": "regex",
      "pattern": "\\s+",
      "replacement": "-",
      "flags": "g"
    }
  ]
}

Custom Transformers

Define custom transformers globally and reference them by ID throughout your configuration.

Defining Custom Transformers

{
  "transformers": [
    {
      "id": "reverse",
      "type": "custom",
      "handler": "value => value.split('').reverse().join('')"
    },
    {
      "id": "capitalize",
      "type": "custom",
      "handler": "value => value.charAt(0).toUpperCase() + value.slice(1)"
    }
  ]
}

Using Custom Transformers

Reference custom transformers by their ID:

{
  "id": "reversedName",
  "value": "",
  "transformers": ["reverse"]
}

Or combine with other transformers:

{
  "id": "processedName",
  "value": "",
  "transformers": ["trim", "lowercase", "capitalize"]
}

Examples

Complete Configuration with Transformers

{
  "$schema": "https://unpkg.com/@pixpilot/scaffoldfy/schema",
  "name": "transformers-example",
  "description": "Example configuration demonstrating value transformers",
  "prompts": [
    {
      "id": "projectName",
      "message": "What is the project name?",
      "type": "input",
      "required": true,
      "transformers": ["slugify"]
    },
    {
      "id": "description",
      "message": "Project description",
      "type": "input",
      "transformers": ["trim"]
    },
    {
      "id": "authorEmail",
      "message": "Author email",
      "type": "input",
      "transformers": ["lowercase"]
    }
  ],
  "variables": [
    {
      "id": "upperProjectName",
      "value": "",
      "transformers": ["uppercase"]
    },
    {
      "id": "packageName",
      "value": "",
      "transformers": [
        "lowercase",
        {
          "type": "regex",
          "pattern": "-",
          "replacement": "_",
          "flags": "g"
        }
      ]
    },
    {
      "id": "nameLength",
      "value": "computed",
      "transformers": [
        {
          "type": "computed",
          "expression": "projectName.length"
        }
      ]
    }
  ],
  "tasks": [
    {
      "id": "create-readme",
      "name": "Create README",
      "type": "write",
      "config": {
        "file": "README.md",
        "template": "# \n\n\n\nPackage: \nAuthor: \nName Length: \n"
      }
    }
  ]
}

Real-World Use Cases

1. NPM Package Name from Project Name

{
  "prompts": [
    {
      "id": "projectName",
      "message": "Project name",
      "type": "input",
      "transformers": [
        "trim",
        "lowercase",
        {
          "type": "regex",
          "pattern": "[^a-z0-9-]",
          "replacement": "",
          "flags": "g"
        }
      ]
    }
  ]
}

2. Generate Multiple Name Variants

{
  "prompts": [
    {
      "id": "componentName",
      "message": "Component name",
      "type": "input"
    }
  ],
  "variables": [
    {
      "id": "componentKebab",
      "value": "",
      "transformers": ["slugify"]
    },
    {
      "id": "componentPascal",
      "value": "",
      "transformers": [
        {
          "type": "regex",
          "pattern": "[-_\\s]+(.)?",
          "replacement": "$1",
          "flags": "g"
        },
        {
          "type": "computed",
          "expression": "componentName.charAt(0).toUpperCase() + componentName.slice(1)"
        }
      ]
    }
  ]
}

3. Clean and Validate Email

{
  "prompts": [
    {
      "id": "email",
      "message": "Email address",
      "type": "input",
      "transformers": ["trim", "lowercase"]
    }
  ]
}

Best Practices

Chain Order Matters: Apply transformers in logical order (e.g., trim before lowercase)
Use Built-ins First: Leverage built-in transformers for common operations
Keep Custom Simple: Complex logic is better in computed transformers
Test Expressions: Verify computed transformer expressions work with your data
Document Custom Transformers: Add descriptions for reusable custom transformers

Limitations

Custom transformer handlers must be valid JavaScript arrow function expressions
Computed expressions have access to configuration context but not Node.js modules
Transformers run synchronously - async operations are not supported
Regex transformers use JavaScript RegExp - some advanced features may not be available

Value Transformers

Table of Contents

Overview

Key Features

Built-in Transformers

lowercase

uppercase

trim

slugify

capitalize

titlecase

capitalCase

camelcase

pascalcase

snakecase

kebabcase

constantcase

alphanumeric

collapse-spaces

remove-spaces

urlencode

dasherize

underscore

adaCase

cobolCase

dotNotation

pathCase

spaceCase

trainCase

upperCamelCase

Transformer Types

Regex Transformer

Computed Transformer

Using Transformers

On Prompts

On Variables

Transformer Chains

Complex Chain Example

Custom Transformers

Defining Custom Transformers

Using Custom Transformers

Examples

Complete Configuration with Transformers

Real-World Use Cases

1. NPM Package Name from Project Name

2. Generate Multiple Name Variants

3. Clean and Validate Email

Best Practices

Limitations

See Also

`lowercase`

`uppercase`

`trim`

`slugify`

`capitalize`

`titlecase`

`capitalCase`

`camelcase`

`pascalcase`

`snakecase`

`kebabcase`

`constantcase`

`alphanumeric`

`collapse-spaces`

`remove-spaces`

`urlencode`

`dasherize`

`underscore`

`adaCase`

`cobolCase`

`dotNotation`

`pathCase`

`spaceCase`

`trainCase`

`upperCamelCase`