npm package: @idot-digital/joi-to-typescript
Description: Convert Joi Schemas to TypeScript interfaces
Author: Jono Clarnette
Latest version: 4.4.6

# joi-to-typescript

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[joi-to-typescript on GitHub](https://github.com/mrjono1/joi-to-typescript)

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[npm-url]: https://www.npmjs.com/package/joi-to-typescript

Convert [Joi](https://github.com/sideway/joi) Schemas to TypeScript interfaces

Now supporting ESM and CJS Modules

This will allow you to use generate TypeScript interfaces from Joi Schemas giving you confidence the schema and interface match. You no longer have to manually create the same structure again, saving you time and reducing errors.

Works with any TypeScript project and also perfectly with [Hapi](https://github.com/hapijs/hapi) API requests/responses.

For generating Open Api/Swagger this project works with

- [joi-to-swagger](https://github.com/Twipped/joi-to-swagger) using `.meta({className:''})`
- [hapi-swagger](https://github.com/glennjones/hapi-swagger) using `.label('')`

The use of `.meta({className:'')` is preferred over `.label('')`, because `Joi.label()` is intended to be used for meaningful error message, using it for another purpose makes Joi lose a standard feature, this is especially noticeable for frontend usages of Joi. The choice of the property `className` is because this property is used by joi-to-swagger making this project work with other projects.

## Installation Notes

This package is intended as a development time tool, so it should be installed in the `devDependencies`

```bash
yarn add joi-to-typescript --dev
# or
npm install joi-to-typescript --save-dev
```

You will also need to install `joi` in the `dependencies`

```bash
yarn add joi
# or
npm install joi
```

- This has been built for `"joi": "^17"` and will not work for older versions
- Minimum node version 12 as Joi requires node 12

## Suggested Usage

1. Create a Schemas Folder eg. `src/schemas`
1. Create a interfaces Folder eg. `src/interfaces`
1. Create Joi Schemas in the Schemas folder with a file name suffix of Schemas eg. `AddressSchema.ts`
   - The file name suffix ensures that type file and schema file imports are not confusing

## Example

#### Example Project

Explore the [Example Projects](https://github.com/mrjono1/joi-to-typescript/tree/master/examples) for recommended setup, execute `yarn types` to run each one.

#### Example Schema

This example can be found in `src/__tests__/readme`

```typescript
import Joi from 'joi';

// Input
export const JobSchema = Joi.object({
  businessName: Joi.string().required(),
  jobTitle: Joi.string().required()
}).meta({ className: 'Job' });

export const WalletSchema = Joi.object({
  usd: Joi.number().required(),
  eur: Joi.number().required()
})
  .unknown()
  .meta({ className: 'Wallet', unknownType: 'number' });

export const PersonSchema = Joi.object({
  firstName: Joi.string().required(),
  lastName: Joi.string().required().description('Last Name'),
  job: JobSchema,
  wallet: WalletSchema
}).meta({ className: 'Person' });

export const PeopleSchema = Joi.array()
  .items(PersonSchema)
  .required()
  .meta({ className: 'People' })
  .description('A list of People');

// Output
/**
 * This file was automatically generated by joi-to-typescript
 * Do not modify this file manually
 */

export interface Job {
  businessName: string;
  jobTitle: string;
}

/**
 * A list of People
 */
export type People = Person[];

export interface Person {
  firstName: string;
  job?: Job;
  /**
   * Last Name
   */
  lastName: string;
  wallet?: Wallet;
}

export interface Wallet {
  /**
   * Number Property
   */
  [x: string]: number;
  eur: number;
  usd: number;
}
```

##### Points of Interest

- `export const PersonSchema` schema must be exported
- `export const PersonSchema` includes a suffix of Schema so the schema and interface are not confused when using `import` statements (recommended not required)
- `.meta({ className: 'Person' });` Sets `interface` name using TypeScript conventions (TitleCase Interface name, camelCase property name)
- `.meta({ unknownType: 'number' });` assert unknown type to `number`

#### Upgrade Notice

- Version 1 used `.label('Person')` as the way to define the `interface` name, to use this option set `{ useLabelAsInterfaceName: true }`

#### Example Call

```typescript
import { convertFromDirectory } from 'joi-to-typescript';

convertFromDirectory({
  schemaDirectory: './src/schemas',
  typeOutputDirectory: './src/interfaces',
  debug: true
});

// or to get an interface as a string. Please note that this method is limited
import { convertSchema } from 'joi-to-typescript';
const resultingInterface = convertSchema({}, JobSchema);
resultingInterface?.content = // the interface as a string
```

## Settings

```typescript
export interface Settings {
  /**
   * The input/schema directory
   * Directory must exist
   */
  schemaDirectory: string;
  /**
   * The output/type directory
   * Will also attempt to create this directory
   */
  typeOutputDirectory: string;
  /**
   * Use .label('InterfaceName') instead of .meta({className:'InterfaceName'}) for interface names
   */
  useLabelAsInterfaceName: boolean;
  /**
   * Should interface properties be defaulted to optional or required
   * @default false
   */
  defaultToRequired: boolean;
  /**
   * What schema file name suffix will be removed when creating the interface file name
   * @default "Schema"
   * This ensures that an interface and Schema with the file name are not confused
   */
  schemaFileSuffix: string;
  /**
   * If `true` the console will include more information
   * @default false
   */
  debug: boolean;
  /**
   * File Header content for generated files
   */
  fileHeader: string;
  /**
   * If true will sort properties on interface by name
   * @default true
   */
  sortPropertiesByName: boolean;
  /**
   * If true will not output to subDirectories in output/interface directory. It will flatten the structure.
   */
  flattenTree: boolean;
  /**
   * If true will only read the files in the root directory of the input/schema directory. Will not parse through sub-directories.
   */
  rootDirectoryOnly: boolean;
  /**
   * If true will write all exports *'s to root index.ts in output/interface directory.
   */
  indexAllToRoot: boolean;
  /**
   * Comment every interface and property even with just a duplicate of the interface and property name
   * @default false
   */
  commentEverything: boolean;
  /**
   * List of files or folders that should be ignored from conversion. These can either be
   * filenames (AddressSchema.ts) or filepaths postfixed with a / (addressSchemas/)
   * @default []
   */
  ignoreFiles: string[];
  /**
   * The indentation characters
   * @default '  ' (two spaces)
   */
  indentationChacters: string;
  /**
   * If a field has a default and is optional, consider it as required
   * @default false
   */
  treatDefaultedOptionalAsRequired: boolean;
  /**
   * If a field has a default, modify the resulting field to equal
   * `field: <default> | type` rather than `field: type`
   * @default false
   */
  supplyDefaultsInType: boolean;
  /**
   * Filter files you wish to parse
   * The class `InputFileFilter` contains some default options
   * @default *.ts files
   */
  inputFileFilter: RegExp;
}
```

## Joi Features Supported

- `.meta({className:'InterfaceName'})` - interface Name and in jsDoc
- `.description('What this interface is for')` - jsdoc
- `.optional()` - optional properties `?`
- `.required()` - required properties
- `.valid(['red', 'green', 'blue'])` - enumerations - `allow` can be used for enumerations but `valid` works better see `_tests_/allow/allow.ts` for more information
- `.allow('')` - will be ignored on a string
- `.allow(null)` - will add as an optional type eg `string | null`
- `.array()`, `.object()`, `.string()`, `.number()`, `.boolean()` - standard Joi schemas
- `.alternatives()` - try is supported, conditionals would be converted to `any`
- `.unknown(true)` - will add a property `[x: string]: unknown;` to the interface
  - Assert `unknown` to some type with a stringified type or a Joi schema, e.g.:
  ```typescript
    .meta({ unknownType: 'some-type' })
  ```
  ```typescript
    .meta({ unknownType: Joi.object({ id: Joi.string() }) })`
  ```
- `.example()` - jsdoc
- `.cast()` - currently will honor casting to string and number types, map and set to be added later
- `.forbidden()` will set the type to `undefined`
- `.meta({ readonly: true })` to create readonly properties like `readonly property: string;`
- And many others

## Contributing

- Raise or comment on an [Issue](https://github.com/mrjono1/joi-to-typescript/issues) with a bug or feature request
- Contribute code via Raising a [Pull Request](https://github.com/mrjono1/joi-to-typescript/pulls)
- Start a [Discussion](https://github.com/mrjono1/joi-to-typescript/discussions)

### Recommended Development Environment

Recommended Editor is VS Code, this project is setup with VSCode settings in the `./.vscode` directory to keep development consistent.

Best developed on macOS, Linux, or on Windows via WSL.
Node 14, 16 or 18

Install [nodejs](https://nodejs.org/) via [nvm](https://github.com/nvm-sh/nvm) so you can have multiple versions installed

```bash
nvm use # using NVM to select node version
yarn install # using yarn
yarn test # run local tests

yarn coverage # test coverage report
yarn lint # lint the code
```

### Change Log

See [GitHub Releases](https://github.com/mrjono1/joi-to-typescript/releases)