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Typescript type camelCase / snake_case conversion
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type CamelCase<S extends string> = S extends `${infer P1}_${infer P2}${infer P3}` | |
? `${Lowercase<P1>}${Uppercase<P2>}${CamelCase<P3>}` | |
: Lowercase<S> | |
type KeysToCamelCase<T> = { | |
[K in keyof T as CamelCase<string & K>]: T[K] | |
} | |
type CamelToSnakeCase<S extends string> = S extends `${infer T}${infer U}` ? | |
`${T extends Capitalize<T> ? "_" : ""}${Lowercase<T>}${CamelToSnakeCase<U>}` : | |
S | |
type KeysToSnakeCase<T> = { | |
[K in keyof T as CamelToSnakeCase<string & K>]: T[K] | |
} |
You can define a type that removes the first character if it's an underscore and utilize that
type RemoveUnderscoreFirstLetter<S extends string> =
S extends `${infer FirstLetter}${infer U}`
? `${FirstLetter extends "_" ? U : `${FirstLetter}${U}`}`
: S;
type CamelToSnakeCase<S extends string> =
S extends `${infer T}${infer U}`
? `${T extends Capitalize<T> ? "_" : ""}${RemoveUnderscoreFirstLetter<
Lowercase<T>
>}${CamelToSnakeCase<U>}`
: S;
type KeysToSnakeCase<T extends object> = {
[K in keyof T as CamelToSnakeCase<K & string>]: T[K];
};
This doesn't work for objects keys in arrays like this:
const data = {
name: 'Rocket',
parts: [ { brandName: 'starx' }]
}
Thanks for sharing!
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I was using type
KeysToSnakeCase
, passing it an object that already has snake case results in it having 2 underscores: