Schema Modifiable

What?

Check out @zuze/schema and @zuze/modifiable and then come back.

And now...

Same reason as @zuze/modifiable came about - manipulating application (or some kind of) state in response to changes in external context (user input, websocket events, etc).

SchemaModifiable

SchemaModifiable allows you to create modifiers as AST Schema Definitions.

import { schemaModifiable } from '@zuze/schema-modifiable';

ModifiableDescriptor

A modifiable descriptor is a plain javascript object that defines its own modifiers at a special key called modifier (the key can be configured using options).

All you need to do to determine a state is supply the context. All of your modification logic has already been encoded in the state itself:

import { modifiableDescriptor } from '@zuze/schema-modifiable';


const myModifiableDescriptor = modifiableDescriptor({
  // the descriptor part
  schema: 'string',
  tests: ['required', ['is', 'freddie']],
  field: {
    type: 'select',
    options: ['freddie', 'roger', 'doug', 'jim'],
    properties: {
        key: 'value'
    }
  },


  // the modifications
  modifier: {
    // values at these paths should be interpolated using the context object
    interpolate: ['hint'],

    // values at these paths will never be overridden
    keep: ['schema'],

    // values at these paths will be appended by conditions, if applicable
    append: ['field.options'],

    // values at these paths will be merged with conditions, if applicable
    merge: ['field.properties'],

    conditions: [
      {
        when: { value: { tests: ['required' ] } },
        then: {
            when: { value: { tests: [['oneOf', { ref: '$field.options' } ]] } },
            then: {
                when: { value: { tests: [['is', 'freddie']] } },
                then: { hint: 'yay! you selected freddie!' },
                otherwise: { hint: 'boo, why not freddie?' },                
            },
            otherwise: { hint: '{value} is not one of the options' },
        },
        otherwise: { hint: 'select an option' },
      },
    ],
  },
});

myModifiableDescriptor.getState();
/*
{
  schema: 'string',
  tests: ['required', ['is', 'freddie']],
  field: {
    type: 'select',
    options: ['freddie', 'roger', 'doug', 'jim'],
  },
  hint: 'select an option'
}
*/

myModifiableDescriptor.setContext({value: 'not an option'});
/*
{
  ...
  hint: 'not an option is not one of the options'
}
*/

myModifiableDescriptor.setContext({value: 'jim'});
/*
{
  ...
  hint: 'boo, why not freddie?'
}
*/

myModifiableDescriptor.setContext({value: 'freddie'});
/*
{
  ...
  hint: 'yay! you selected freddie!'
}
*/

API