Extenting Type interface

I want to make a custom function type({}).migrate() and add it to BaseType prototype How do I do it properly?

2 Replies

Sadly would be very convoluted. You'd have to do something hacky like modifying the BaseRoot prototype directly to add it or you could create a constructor that just delegates to arktype then assigns the extra method to it

DimavaOP•3mo ago

import type { Type } from 'arktype'
import type { Out } from 'arktype/out/keywords/inference'
import { BaseRoot } from '@ark/schema'
import { type } from 'arktype'

declare module 'arktype/out/methods/base' {
  interface BaseType {
    migrate(...migrators: type.Any[]): Type<(In: unknown) => Out<this['infer']>>
  }
}

Object.assign(BaseRoot.prototype, {
  migrate(this: type.Any, ...migrations: type.Any[]) {
    return type('unknown.any')
      .pipe((v, _ctx) => {
        const result = this(v)
        if (!(result instanceof type.errors))
          return result
        for (const migration of migrations) {
          const migResult = migration(v)
          if (!(migResult instanceof type.errors)) {
            v = migResult
          }
        }
        return this(v)
      })
  },
})

import type { Type } from 'arktype'
import type { Out } from 'arktype/out/keywords/inference'
import { BaseRoot } from '@ark/schema'
import { type } from 'arktype'

declare module 'arktype/out/methods/base' {
  interface BaseType {
    migrate(...migrators: type.Any[]): Type<(In: unknown) => Out<this['infer']>>
  }
}

Object.assign(BaseRoot.prototype, {
  migrate(this: type.Any, ...migrations: type.Any[]) {
    return type('unknown.any')
      .pipe((v, _ctx) => {
        const result = this(v)
        if (!(result instanceof type.errors))
          return result
        for (const migration of migrations) {
          const migResult = migration(v)
          if (!(migResult instanceof type.errors)) {
            v = migResult
          }
        }
        return this(v)
      })
  },
})

I guess this works well enough then

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Extenting Type interface