Schema2TypeBox

Creating TypeBox code from JSON schemas.

Installation

- npm i -g schema2typebox

Use Case

- You got JSON schemas that you want to validate your data against. But you
also want automatic type inference after validating the data. You have
chosen typebox for this, but figured
that you would need to manually create the typebox code. To avoid this pain, you
simply use schema2typebox to generate the required code for you🎉.

Usage

- The cli can be used with schema2typebox --input --output
, or by simply running schema2typebox. The input defaults to
"schema.json" and the output to "generated-typebox.ts" relative to the current
working directory. For more see cli usage.

Examples

``typescript
//
// Let's start with our JSON schema
//

{
"title": "Person",
"type": "object",
"properties": {
"name": {
"type": "string",
"minLength": 20
},
"age": {
"type": "number",
"minimum": 18,
"maximum": 90
},
"hobbies": {
"type": "array",
"minItems": 1,
"items": {
"type": "string"
}
},
"favoriteAnimal": {
"enum": ["dog", "cat", "sloth"]
}
},
"required": ["name", "age"]
}

//
// Which becomes..
//

export type Person = Static;
export const Person = Type.Object({
name: Type.String({ minLength: 20 }),
age: Type.Number({ minimum: 18, maximum: 90 }),
hobbies: Type.Optional(Type.Array(Type.String(), { minItems: 1 })),
favoriteAnimal: Type.Optional(
Type.Union([
Type.Literal("dog"),
Type.Literal("cat"),
Type.Literal("sloth"),
])
),
});

//
// You can also split your JSON schema definitions into multiple files when
// using relative paths. Something like this:
//

// person.json
{
"title": "Person",
"type": "object",
"properties": {
"name": {
"type": "string",
"maxLength": 100
},
"age": {
"type": "number",
"minimum": 18
}
},
"required": ["name", "age"]
}

// status.json
{
"title": "Status",
"enum": ["unknown", "accepted", "denied"]
}

// schema.json
{
"title": "Contract",
"type": "object",
"properties": {
"person": {
"$ref": "./person.json"
},
"status": {
"$ref": "./status.json"
}
},
"required": ["person"]
}

//
// Will result in this:
//

export type Contract = Static;
export const Contract = Type.Object({
person: Type.Object({
name: Type.String({ maxLength: 100 }),
age: Type.Number({ minimum: 18 }),
}),
status: Type.Optional(
Type.Union([
Type.Literal("unknown"),
Type.Literal("accepted"),
Type.Literal("denied"),
])
),
});

//
// For an example of programmatic usage check out the examples folder.
//

`

Please take a look at the feature list below to see the
currently supported features. For examples, take a look into the
examples folder.
You can also check the test cases, every feature is tested.

$3

The package is focused on supporting JSON schema draft-07 files, since this is
the target TypeBox officially supports. _These types are fully compatible with
the JSON Schema Draft 7 specification._ (from typebox repo 20.08.2023).

However, since the amount of breaking changes is quite small between most JSON
schema specs, support for other specs (draft-04, draft-06, draft-2019-09) should
"just work". Feel free to open a discussion or issue when you find problems.
Happy about contributions if you want to help out. Draft-2020 info can be found
here not expected to fully
work.

DEV/CONTRIBUTOR NOTES

If you have an idea or want to help implement something, feel free to do so.
Please always start by creating an issue to avoid any unnecessary work on
either side.

Please always create tests for new features that are implemented. This will
decrease mental overhead for reviewing and developing in the long run.

To understand the JSON schema draft-07 you can check json-schema.org
here. The meta
schema can be found here.

cli usage

The following text is the output that will be displayed when you issue
schema2typebox -h or schema2typebox --help.

`

schema2typebox generates TypeBox code from JSON schemas. The generated
output is formatted based on the prettier config inside your repo (or the
default one, if you don't have one). Version: ${packageJson.version}

Usage:

schema2typebox [ARGUMENTS]

Arguments:

-h, --help
Displays this menu.

-i, --input
Specifies the relative path to the file containing the JSON schema that
will be used to generated typebox code. Defaults to "schema.json".

-o, --output
Specifies the relative path to generated file that will contain the
typebox code. Defaults to "generated-typebox.ts".

--output-stdout
Does not generate an output file and prints the generated code to stdout
instead. Has precedence over -o/--output.

`

$3

This project aims for a high code coverage to keep maintenance low. When you add
new features or fix a bug, please add an according test for it. The current
(08.06.2024) coverage looks like this:

| File | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s |
| --------------------- | ------- | -------- | ------- | ------- | -------------------------------- |
| All files | 94.76 | 89.87 | 97.29 | 94.76 |
| cli.ts | 100 | 100 | 100 | 100 |
| index.ts | 100 | 100 | 100 | 100 |
| programmatic-usage.ts | 100 | 100 | 100 | 100 |
| schema-matchers.ts | 97.33 | 100 | 91.66 | 97.33 | 70-71 |
| schema-to-typebox.ts | 92.56 | 88.32 | 100 | 92.56 | ... (manually cut to fit readme) |

You can inspect the code coverage in depth by running npx http-server
./coverage/lcov-report` and then browsing http://localhost:8080.

$3

Template for this repo was taken from here.