@buka/class-transformer-extra

@buka/class-transformer-extra contains methods that's aren't included in the class-transformer package.

Install

npm install @buka/class-transformer-extra class-transformer
# OR
yarn install @buka/class-transformer-extra class-transformer
# OR
pnpm install @buka/class-transformer-extra class-transformer

Usage

String

| method | before transformer | after transformer | | :------------------------------ | :----------------- | :---------------- | | @Split(",") | "a,b,c" | ["a", "b", "c"] | | @Trim() | " abc " | "abc" | | @ToString({ optional: true }) | 123 | "123" | | @ToLowerCase() | "ABC" | "abc" | | @ToUpperCase() | "abc" | "ABC" | | @Replace("-", "_") | "a-b-c" | "a_b_c" |

@Split, @Trim, @ToLowerCase, @ToUpperCase and @Replace will do nothing if the value isn't string. When set optional: true, undefined will not be transformed.

Date

| method | before transformer | after transformer | | :---------------------------------------------- | :----------------- | :----------------------- | | @ToDate({ optional: true }) | "2024-01-01" | new Date("2024-01-01") | | @FormatDate("YYYY/MM/DD", { optional: true }) | "2024-01-01" | "2024/01/01" |

Number

| method | before transformer | after transformer | | :------------------------------ | :----------------- | :---------------- | | @ToNumber({ optional: true }) | "123" | 123 | | @ToBigInt({ optional: true }) | "123" | 123n |

ToNumber() and @ToBigInt() will return NaN if the value isn't number

Boolean

| method | before transformer | after transformer | | :------------- | :----------------- | :---------------- | | @ToBoolean() | 1 | true |

ToBoolean() has multiple parameters to adapt to different needs, examples:

ToBoolean(v => Boolean(v)), { optional: true }): If the value is undefined, do nothing. Otherwise, v => Boolean(v) will be used to transform value.

ToBoolean(['0', 'false', false], { optional: true }):

If the value is '0' or 'false' or false, transform to false, and if the value is undefined, do nothing, otherwise value will be transform to true.

Array

| method | before transformer | after transformer | | :---------------------------------- | :---------------------- | :---------------- | | @Filter((num: number) => num > 3) | [1,2,3.4,5] | [4,5] | | @Flatten() | [1, [2, [3, 4, [5]]]] | [1,2,3,4,5] | | @Uniq() | [1,1,2,3,4,4,5] | [1,2,3,4,5] | | @UniqBy(Math.abs) | [-1, 1, 2, 3, -3] | [-1, 2, 3] |

@Filter, @Flatten, @Uniq and @UniqBy will do nothing if the value isn't array.

Contribute

If you want to report bug or add new decorators, please submit an Issue or Pull Request.

Q&A

1. Why can't it be used with the @IsOptional decorator?

   The latest version of class-validator@^0.14.1 is not set metadata that can identify @IsOptional. If the identifiers are added in later versions, I will also follow up. And the identifier had be add in develop branch of class-validator.