https://github.com/danielgtaylor/eidolon
Generate JSON or JSON Schema from Refract & MSON data structures
https://github.com/danielgtaylor/eidolon
Last synced: over 1 year ago
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Generate JSON or JSON Schema from Refract & MSON data structures
- Host: GitHub
- URL: https://github.com/danielgtaylor/eidolon
- Owner: danielgtaylor
- License: mit
- Created: 2016-01-29T00:39:18.000Z (over 10 years ago)
- Default Branch: master
- Last Pushed: 2019-02-20T11:24:36.000Z (over 7 years ago)
- Last Synced: 2025-05-08T23:47:59.248Z (over 1 year ago)
- Language: CoffeeScript
- Size: 43 KB
- Stars: 6
- Watchers: 3
- Forks: 1
- Open Issues: 4
-
Metadata Files:
- Readme: README.md
- Changelog: Changelog.md
- License: LICENSE
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README
# Eidolon
[](https://travis-ci.org/danielgtaylor/eidolon) [](https://coveralls.io/r/danielgtaylor/eidolon) [](https://www.npmjs.org/package/eidolon) [](https://www.npmjs.org/package/eidolon)
Generate examples and [JSON Schema](http://json-schema.org/) from [Refract](https://github.com/refractproject/refract-spec#refract) data structures. Data structures can come from [MSON](https://github.com/apiaryio/mson#markdown-syntax-for-object-notation) or other input sources.
Given the following MSON attributes from e.g. [API Blueprint](https://apiblueprint.org/):
```apib
+ Attributes
+ name: Daniel (required) - User's first name
+ age: 10 (required, number) - Age in years
```
It would generate the following JSON example and JSON Schema:
```json
{
"name": "Daniel",
"age": 10
}
```
```json
{
"$schema": "http://json-schema.org/draft-04/schema#",
"type": "object",
"required": ["name", "age"],
"properties": {
"name": {
"type": "string",
"description": "User's first name"
},
"age": {
"type": "number",
"description": "Age in years"
}
}
}
```
## Installation & Usage
This project is available via `npm`:
```sh
npm install eidolon
```
There are two ways to use the module: either via module-level methods or by instantiating a class instance.
```js
import eidolon, {Eidolon} from 'eidolon';
const input = {"element": "string", "content": "Hello"};
const dataStructures = {};
let example, schema;
// Method 1: module methods
example = eidolon.example(input, dataStructures, options);
schema = eidolon.schema(input, dataStructures);
// Method 2: class instance
const instance = new Eidolon(dataStructures, options);
example = instance.example(input);
schema = instance.schema(input);
```
Choose whichever method better suits your use case.
#### Example & Schema Serialization
Examples and JSON Schema are created as plain Javascript objects. As such, they can be serialized into various formats, such as JSON, YAML, and other more esoteric formats. In the case of JSON Schema, it probably makes the most sense to stick with JSON.
```js
example = instance.example(input);
// Print as JSON
console.log(JSON.stringify(example, null, 2));
// Print as YAML (after `npm install js-yaml`)
import yaml from 'js-yaml';
console.log(yaml.safeDump(example));
```
## Features
The following features are supported by the example and JSON Schema generators. Note that not all MSON features are supported (yet)!
### Example Generator
* Simple types, enums, arrays, objects
* Property descriptions
* References
* Mixins (Includes)
* Arrays with members of different types
* One Of properties (the first is always selected)
* Circular references generated as `null`
### JSON Schema Generator
* Simple types, enums, arrays, objects
* Property descriptions
* Required, default, nullable properties
* References
* Mixins (Includes)
* Arrays with members of different types
* One Of (mutually exclusive) properties
* Circular references generated as an empty schema
### Notable Missing Features
The following list of features in no particular order are known to be missing or cause issues. Please feel free to open a pull request with new features and fixes based on this list! *wink wink nudge nudge* :beers:
* Better support for circular references
* Variable values
* Variable property names
* Variable type names
* Extend element support
* Remote referenced elements (e.g. via HTTP)
* Namespace prefixes
## Link Relations
Elements may be given [link relations](https://github.com/refractproject/refract-spec/blob/master/refract-spec.md#link-element-element) when dereferencing or processing inheritance that help to describe the origin of a particular element, such as wheterh it was included vs. inherited or whether the element constitutes a circular reference to a previous element in the hierarchy.
### Inheritance
Inheritance link relations come in two forms. The first, called `inherited` is for the element which inherits from another element. The second, called `inherited-member` is for elements of type `member` within an `object` that have been inherited from a parent `object`. MSON example:
```mson
# MyObject (MyBase):
+ id (number)
```
### Inclusion
Inclusion link relations are for elements of type `member` within an `object` that have been included from a parent `object`. MSON example:
```mson
# MyObject
+ Include MyBase
```
### Circular References
Circular reference link relations are for elements whose ancestral chain contains itself, causing a loop. Processing will stop and this link relation will be added so you can detect this case. MSON example:
```mson
# Person
+ address (Address)
# Address
+ owner (Person)
```
### Origins and Link Definitions
Description | Relation | Href
------------------ | -------- | ----
Inherited | `origin` | http://refract.link/inherited/
Inherited member | `origin` | http://refract.link/inherited-member/
Included member | `origin` | http://refract.link/included-member/
Circular reference | `origin` | http://refract.link/circular-reference/
## Reference
### `eidolon.Eidolon([dataStructures], [options])`
This class is used to save state between calls to `example` and `schema`. It is used just like the functions below, except that you pass your data structures to the constructor instead of to each method.
Available options:
Option Name | Description | Default
------------ | ----------- | -------
`defaultValue` | Function to generate a default value `function (refractElement, path)` | Built-in [`eidolon.defaultValue`](https://github.com/danielgtaylor/eidolon/blob/master/src/default-value.coffee).
`seed` | Seed for the random generator used to create default values | -
```js
import {Eidolon} from 'eidolon';
const instance = new Eidolon();
const input = {element: 'string', content: 'hello'};
let example = instance.example(input);
let schema = instance.schema(input);
let dereferenced = instance.dereference(input);
```
### `eidolon.example(input, [dataStructures], [options])`
Generate a new example from the given input refract object and an optional mapping of data structures, where the key is the data structure name and the value is the data structure definition.
Available options are described in the Eidolon class above.
```js
import eidolon from 'eidolon';
const input = {element: 'string', content: 'hello'};
let example = eidolon.example(input);
```
### `eidolon.schema(input, [dataStructures])`
Generate a new JSON schema from the given input refract object and an optional mapping of data structures, where the key is the data structure name and the value is the data structure definition.
```js
import eidolon from 'eidolon';
const input = {element: 'string', content: 'hello'};
let schema = eidolon.schema(input);
```
### `eidolon.dereference(input, [dataStructures], [known])`
Dereference an input element or structure of elements with the given data structures. This will return the same element or structure with resolved references so you do not have to handle inheritance or object includes. Each resolved reference will include the name of the referenced type or mixin in the [`meta.ref` property](https://github.com/refractproject/refract-spec/blob/master/refract-spec.md#properties). If given, `known` is an array of element names from ancestors of this element, used to detect circular references.
```js
import eidolon from 'eidolon';
const input = {
element: 'MyString'
};
const dataStructures = {
MyElement: {
element: 'string',
meta: {
id: 'MyString'
},
content: 'Hello, world!'
}
};
let dereferenced = eidolon.dereference(input, dataStructures);
console.log(dereferenced.element); // => 'string'
console.log(dereferenced.content); // => 'Hello, world!'
console.log(dereferenced.meta.ref); // => 'MyString'
```
### `eidolon.inherit(base, element)`
Generate a new element with merged properties from both `base` and `element`, taking care to prevent duplicate members. This utility can be used when traversing the element tree.
```js
import eidolon from 'eidolon';
const base = {
element: 'number',
meta: {
id: 'NullableNumber',
default: 0
},
attributes: {
typeAttributes: ['nullable']
}
};
const element = {
element: 'NullableNumber',
attributes: {
default: 2
},
content: 10
}
let merged = eidolon.inherit(base, element);
// Merged now looks like:
{
element: 'number',
meta: {
ref: 'NullableNumber',
links: [
{
relation: 'origin',
href: 'http://refract.link/inherited/'
}
]
},
attributes: {
default: 2,
typeAttributes: ['nullable']
},
content: 10
}
```
## License
Copyright © 2016 Daniel G. Taylor
http://dgt.mit-license.org/