CODEWITHSUNDEEP
typescriptlodash
Hunter_71
Hunter_71

Reputation: 789

Type declarations for function calling lodash `mapKeys`

I need a function mapping camelCase object keys to snakeCase. I want to use it multiple times with different objects.

I wrote function mapKeysToSnakeCase that works well, but I wonder if there is possible to use generic types instead of any to improve the definition.

Any advice how it can be done?

export function mapKeysToSnakeCase(data: any): any {
    return mapKeys(data, (value, key) => snakeCase(key));
}

Before:

const camelCase = {
    firstName: 'John',
    lastName: 'Smith',
};

After:

const snakeCase = {
    first_name: 'John',
    last_name: 'Smith',
};

@edit

I tried previously with new type definition (like first answer suggested), but I end up with warning in usage context and it is why I want to use some generic types for it.

sync getData(): Promise<X> {
    (...)
    return mapKeysToSnakeCase(camelCaseX);
}

error:

TS2741: Property 'first_name' is missing in type 'KV' but required in type 'X'.

Upvotes: 0

Views: 1580

Answers (2)

Hunter_71
Hunter_71

Reputation: 789

I ask my team mate to help me with this and he prepared best suited solution:

export function mapKeysToSnakeCase<R>(data: Record<string, any>): R {
    return mapKeys(data, (value, key) => snakeCase(key)) as R;
}

well fit with context like:

sync getData(): Promise<X> {
    (...)
    return mapKeysToSnakeCase<X>(camelCaseX);
}

Upvotes: 1

stck
stck

Reputation: 82

You can define key-value type as follows:

type KV = { [x: string]: string }; // x is an key of type string and value have string type too

and use it:

export function mapKeysToSnakeCase(data: KV): KV {
  return mapKeys(data, (value, key) => snakeCase(key));
}

Upvotes: 0

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