How to access a dynamic key in Typescript

Question

I have the following code:

type StringMapType<K extends string[]> = Record<K[number], string>

const en = {
  'general': {
    'hi': {
      string: 'Aenean ullamcorper neque id elementum commodo. {{firstName}}',
      params: ['firstName']
    },
     'bye': {
      string: 'Aenean ullamcorper neque id elementum commodo.',
      params: null
    }
  },
} as const


const getLocalizedString = <ContextType extends keyof typeof en, KeyType extends keyof typeof en[ContextType], ParamsType extends typeof en[ContextType][KeyType]['params']>(context: ContextType, key: KeyType, ...params: typeof en[ContextType][KeyType]['params'] extends null ? [undefined?] : [StringMapType<ParamsType>]) => {
  // Code that would return the correct value
}


getLocalizedString('general', 'hi', {
  firstName: 'John'
})

For some reason, I'm getting an error on the ParamsType saying that Type '"params"' cannot be used to index type. The code itself works and does what I want, just wondering if there is any way how to get around this error.

Demo

Thanks in advance

Solution

Based on @seti's answer

const en = {
  general: {
    hi: {
      string: 'hi, {{firstName}}',
      params: ['firstName'] as const,
    },
    bye: {
      string: 'bye',
      params: [] as const,
    }
  },
} as const

const translations = {
  en,
} as const

const language = 'en'

type CT = keyof typeof en
type KT = keyof typeof en[CT]
type ParamsType<KeyType extends KT> = typeof en[CT][KeyType]['params'][number]
type StringType<KeyType extends KT> = typeof en[CT][KeyType]['string']

const getLocalizedString = <ContextType extends CT = CT, KeyType extends KT = KT>(
  context: ContextType,
  key: KeyType,
  ...params: ParamsType<KeyType> extends undefined ? [undefined?] : [{ [key in ParamsType<KeyType>]: string }]
): StringType<KeyType> => {

  return translations[language][context][key].string
}

getLocalizedString('general', 'hi', {firstName: 'John'})

getLocalizedString('general', 'bye')

Answer 1

I think maybe rvm just doesnt work properly on m1 yet? Try just using brew install ruby for now. It should work the same.