这个包实际上是著名的 ExpressJS multer v2.0.0-rc.4 原生包的一个分支。主要对于那些喜欢 Promise 风格编程而不是中间件的开发人员来说会很有趣。此外，同样重要的是，这个包是用 TypeScript 编写的，因此其中的类型支持和上下文文档都是一流的。
确保您已安装 Node.js >= v20.0.6。可以使用以下命令安装该软件包：
npm install @ts-stack/multer
Multer 返回一个具有四个属性的对象：formFields、file、files 和 groups。 formFields 对象包含表单文本字段的值，file、files 或 groups 对象包含通过表单上传的文件（作为可读流）。
以下示例仅为了简单起见而使用 ExpressJS。事实上，@ts-stack/multer 不返回中间件，因此对于 ExpressJS 来说不如原始模块方便。基本用法示例：
import { Multer } from '@ts-stack/multer';
import express from 'express';
import { createWriteStream } from 'node:fs';
// Here `avatar`, `photos` and `gallery` - is the names of the field in the HTML form.
const multer = new Multer({ limits: { fileSize: '10MB' } });
const parseAvatar = multer.single('avatar');
const parsePhotos = multer.array('photos', 12);
const parseGroups = multer.groups([{ name: 'avatar', maxCount: 1 }, { name: 'gallery', maxCount: 8 }]);
const app = express();
app.post('/profile', async (req, res, next) => {
const parsedForm = await parseAvatar(req, req.headers);
// parsedForm.file is the `avatar` file
// parsedForm.formFields will hold the text fields, if there were any
const path = `uploaded-files/${parsedForm.file.originalName}`;
const writableStream = createWriteStream(path);
parsedForm.file.stream.pipe(writableStream);
// ...
});
app.post('/photos/upload', async (req, res, next) => {
const parsedForm = await parsePhotos(req, req.headers);
// parsedForm.files is array of `photos` files
// parsedForm.formFields will contain the text fields, if there were any
const promises: Promise<void>[] = [];
parsedForm.files.forEach((file) => {
const promise = new Promise<void>((resolve, reject) => {
const path = `uploaded-files/${file.originalName}`;
const writableStream = createWriteStream(path);
file.stream.pipe(writableStream);
writableStream.on('finish', resolve);
writableStream.on('error', reject);
});
promises.push(promise);
});
await Promise.all(promises);
// ...
});
app.post('/cool-profile', async (req, res, next) => {
const parsedForm = await parseGroups(req, req.headers);
// parsedForm.groups is an object (String -> Array) where fieldname is the key, and the value is array of files
//
// e.g.
// parsedForm.groups['avatar'][0] -> File
// parsedForm.groups['gallery'] -> Array
//
// parsedForm.formFields will contain the text fields, if there were any
});
如果您需要处理纯文本的多部分表单，可以使用 .none() 方法，例如：
import { Multer } from '@ts-stack/multer';
import express from 'express';
const parseFormFields = new Multer().none();
const app = express();
app.post('/profile', async (req, res, next) => {
const parsedForm = await parseFormFields(req, req.headers);
// parsedForm.formFields contains the text fields
});
这是错误代码列表：
const errorMessages = new Map<ErrorMessageCode, string>([ ['CLIENT_ABORTED', 'Client aborted'], ['LIMIT_FILE_SIZE', 'File too large'], ['LIMIT_FILE_COUNT', 'Too many files'], ['LIMIT_FIELD_KEY', 'Field name too long'], ['LIMIT_FIELD_VALUE', 'Field value too long'], ['LIMIT_FIELD_COUNT', 'Too many fields'], ['LIMIT_UNEXPECTED_FILE', 'Unexpected file field'], ]);
您可以在 MulterError#code 属性中看到这些错误代码：
import { Multer, MulterError, ErrorMessageCode } from '@ts-stack/multer';
// ...
try {
const multer = new Multer().single('avatar');
const parsedForm = await multer(req, req.headers);
// ...
} catch (err) {
if (err instanceof MulterError) {
err.code // This property is of type ErrorMessageCode.
// ...
}
}
以上是@ts-stack/multer 简化了将文件上传到基于 Node.js 的后端的详细内容。更多信息请关注PHP中文网其他相关文章！
