HighlightResult/SnippetResult do not support Array key types

[daniel-shuy]

HighlightResult/SnippetResult are defined as:

export type HighlightResult<THit> = THit extends string | number
  ? HighlightMatch
  : {
      [KAttribute in keyof THit]?: HighlightResult<THit[KAttribute]>;
    };

export type SnippetResult<THit> = THit extends string | number
  ? SnippetMatch
  : {
      [KAttribute in keyof THit]: SnippetResult<THit[KAttribute]>;
    };

which resolves to HighlightMatch/SnippetMatch if THit is a string | number, else recurses.

This unfortunately means that array properties/attributes of THit will not resolve to HighlightMatch/SnippetMatch.

See related issue meilisearch/meilisearch-js-plugins#552 (comment)

Since the recursion is meant to support nested Objects, maybe the type definitions can be changed to:

export declare type HighlightResult<THit> = THit extends object
    ? THit extends Array<any>
        ? HighlightMatch
        : {
            [KAttribute in keyof THit]: HighlightResult<THit[KAttribute]>;
        }
    : HighlightMatch;

export declare type SnippetResult<THit> = THit extends object ?
    ? THit extends Array<any>
        ? SnippetMatch
        : {
            [KAttribute in keyof THit]: SnippetResult<THit[KAttribute]>;
        }
    : SnippetMatch;

which would support all primitives and arrays.

I wish TypeScript had an easier way to define (object | !Array). Sadly Exclude<object, Array<any>> doesn't work with object.

[Haroenv]

The suggested change you left isn't syntactically valid. Could you make a typescript playground with the exact change you're proposing? I think you're on a right path, but maybe copied from somewhere wrong!

[daniel-shuy]

https://www.staging-typescript.org/play?#code/C4TwDgpgBAEglgcwBYBtFOAWQIbAMZJQC8UA3gFBRVQBOE2AJgPYB2KIUAbtigK4QAuKAGdgNOCwQBuStTqNW7KAFtcBADIROEFEIDkLVhD1QAPlD1hsNYHB4nzegGa8UKPTOq16zNh1X4SBAMAOpMNAzCQvK+SqLikgDaALqecj6KHC5uIPDIaMjAwQD8QgBGTEwo9CwyAL4y5KCQsOgFGABKEMKuwAA8ACrwwAB8xFBDcMBQEAAeRSyRImISCGZQLLzKZRA0slTFrfnoWGpI+1BCFF5eiQDSAILAK2W8RVASUADWECBMThNhslSkdUCcuj0UP1JsB7k8Xm8IMkRmkqA1yE1wNBMExOHBuuNrtQ4AwQZttrsLrZgNUQfFVhdcbs8RAAO50laSC4ICAsOjCDkJBApcjo8h4ViiFS4-HCPJgwpCeXtYAQ3p9HEs4RjEikdHKGXdZUnAB0PL53SkUAA9NaoM1oHBhFAAAYACmNhRwgXWvEWECcEmCAEoUr7-YGWMEXR8WKIfFB-q7PRhvQRwwwA0GGC6MQ6oAAxOCzYIp1XddUwnWAqYzea8pZMMoAKwgeGAF0OMLrCyWDxoNGwID62BYIBGFy8hzLafON2oV0n86gcOe4le70+Pz+AJhwKERZLDDLaqhg2Gq4RRWRqJudQuSraJ1njQlcemgaPmtlZYPxdLT6FKe-Tft01Z6jIn7BKBcqARgZq8vyVq2vaWIfM6LozmcGZZlGObkEAA

[Haroenv]

I checked, and the current implementation is correct, albeit a little bit overly safe, as the items inside an array can not be undefined. I have tried out a real highlight match which is an array, and also one which is more complicated, and both the current implementation:

type HighlightResult<THit> = THit extends string | number
  ? HighlightMatch
  : {
      [KAttribute in keyof THit]?: HighlightResult<THit[KAttribute]>;
    };

and a suggestion to not infer undefined inside array values:

type MoreExactHighlightResult<THit> = THit extends string | number
  ? HighlightMatch
  : THit extends Array<infer TItem>
  ? Array<MoreExactHighlightResult<TItem>>
  : {
      [KAttribute in keyof THit]?: MoreExactHighlightResult<THit[KAttribute]>;
    };

Work as expected. Why did you expect the value if it's an array to be directly the match, and not an array? I noticed you use meili. If they differ from the spec, they would need to do the mapping to the Algolia format, as InstantSearch and the algoliasearch client are made for our properties.

playground

[daniel-shuy]

@Haroenv I see, thanks, looks like the issue is with MeiliSearch