@buka/class-transformer-extra
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class-transformer-extra contains methods that's aren't included in the class-transform package.
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# @buka/class-transformer-extra
[class-transformer]: https://github.sheincorp.cn/typestack/class-transformer
[npm]: https://www.npmjs.com/package/@buka/class-transformer-extra
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[](https://codecov.io/gh/buka-lnc/npm.class-transformer-extra)
`@buka/class-transformer-extra` contains methods that's aren't included in the [`class-transformer`][class-transformer] package.
## Install
```shell
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`.