schema-settings

JSON Schema based settings provider :gear:

const SSettings = require('schema-settings')
const settings = new SSettings({
  schema: {
    properties: {
      foo: { type: 'string', default: 'bar' }
    }
  },
  location: `${__dirname}/settings.json`
})


const foo = settings.get('foo')

// prints 'bar'
console.log(foo)

I wanted a strongly constrained settings implementation that made it easy for folks to define additional setting constraints (as external plugins). I also wanted it to be easy to use. I think schema-settings does those things well.

API

First, install with npm i schema-settings

global

A global SchemaSettings instance, for use when you don't wish to maintain an instance.

This is designed for electron renderer process workloads, but may be broadly useful. Simply configure once and then reference where needed. For example:

const settings = require('schema-settings`).global
settings.configure({
  schema: {
    properties: {
      todo: {type: 'string', default: 'populate this json schema constraints object' }
    }
  },
  location: './path-on-disk-to-save-settings-to.json'
})

// 'populate this json schema constraints object'
settings.get('todo')

SchemaSettings

constructor

/**
* Creates an instance of SchemaSettings
* 
* By default, this uses coercion and defaults for the provided schema
* 
* @param ISchemaSettingsArgs Ctor args
*/

Arguments:

/**
* The ajv compatible JSONSchema definition
*/
schema : object,

/**
* The location of the settings data file
*/
location : string,

/**
* A readFile implementation
*/
readFile ?: readFileSync,

/**
* A writeFile implementation
*/
writeFile ?: writeFileSync,

/**
* The ajv compilation arguments
*/
ajvArgs ?: Options,

/**
* The separator used to denote object hierarchy in selectors
*/
hierarchySeparator ?: string,

/**
* The separator used to denote the start of array indices in selectors
*/
arrayStartSeparator ?: string,

/**
* The separator used to denote the end of array indices in selectors
*/
arrayEndSeparator ?: string

Example:

const SS = require('schema-settings`)
const settings = new SS({
  schema: {
    properties: {
      todo: {type: 'string', default: 'populate this json schema constraints object' }
    }
  },
  location: './path-on-disk-to-save-settings-to.json'
})

get

/**
* Get's all or a portion of the settings
* @param selector sub object selector
*/

Arguments:

/**
* sub object selector used to determine what portion of the settings object you demand
* Optional
*/
selector ?: string

Example:

const todo = settings.get('todo')

// outputs 'populate this json schema constraints object'
console.log(todo)

getTree

Designed for internal use only

/**
* Get's a portion of settings, maintaining the object tree leading to that portion
* @param selector sub object selector
*/

Arguments:

/**
* sub object selector used to determine what portion of the settings object you demand
* Optional
*/
selector ?: string

Example:

const todoTree = settings.getTree('todo')

// outputs {todo: 'populate this json schema constraints object'}
console.log(todoTree)

set

/**
* Set's a portion of the settings
* @param selector sub object selector
* @param val value to store
*/

Arguments:

/**
* sub object selector used to determine what portion of the settings object you wish to change
* Optional
*/
selector ?: string

/**
* The value you wish to set for settings
* Note: If you omit the selector argument, this argument will be first
*/
val : object

Example:

// will write a new value for 'todo'
settings.set('todo', 'i\'ve done it now!')

walkTree

Designed for internal use only

/**
* Walks toward a selector against a given object and calls callback for each step
* @param selector sub object selector
* @param obj object
* @param cb step callback, given (obj ptr, selector part, selector part index, total selector parts count)
*/

Arguments:

/**
* sub object selector used to determine what portion of the settings object you wish to walk toward
*/
selector : string

/**
* The object you wish to walk over
*/
obj : object

/**
* The callback that will be invoked for each step
* it's given:
*    obj: a pointer to the node in the object we are currently walking on
*    key: the key that we are about to walk into
*    index: the index of the key, as a part of the overall selector
*    keyCount: the number of total keys that makeup the overall selector
*/
cb : (obj : object, key : string, index : number, keyCount : number)

evaluateSelector

/**
* Evaluates a selector against a given object and returns the selected bits
* @param selector sub object selector
* @param obj object
* @param type the evaluation type we use (copy-tree, or reference src object)
*/

Arguments:

/**
* sub object selector used to determine what portion of the settings object you wish to walk toward
*/
selector : string

/**
* The object you wish to walk over
*/
obj : object

/**
* The evaluation type we use ('reference' or 'copy')
* This determines if we reference a part of the larger object in the return type
* or if we copy the object/relevant bits to it's own structure
*/
type : 'reference' | 'copy' = 'reference'

generateSelectors

/**
* Generates selectors for a given object shape
* @param srcObject object for which to generate selectors
*/

Arguments:

/**
* The object you wish to generate selectors for
*/
srcObject : object

Example:

const selectors = settings.generateSelectors({todo: 'hello'})

// outputs ['todo']
console.log(selectors)

License

MIT