为啥当我使用 apollo-server 上传文件时,文件已上传但文件为 0kb?
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【中文标题】为啥当我使用 apollo-server 上传文件时,文件已上传但文件为 0kb?【英文标题】:Why when I upload file with apollo-server the file is uploaded but the file is 0kb?为什么当我使用 apollo-server 上传文件时,文件已上传但文件为 0kb? 【发布时间】:2021-05-01 03:13:02 【问题描述】:我试图解决这个问题,但我不明白为什么文件被上传但他的大小是 0Kb。 我在教程中看到了这段代码,但他在那个教程上工作,但对我不起作用
const ApolloServer, gql = require('apollo-server');
const path = require('path');
const fs = require('fs');
const typeDefs = gql`
type File
url: String!
type Query
hello: String!
type Mutation
fileUpload(file: Upload!): File!
`;
const resolvers =
Query:
hello: () => 'Hello world!',
,
Mutation:
fileUpload: async (_, file ) =>
const createReadStream, filename, mimetype, encoding = await file;
const stream = createReadStream();
const pathName = path.join(__dirname, `/public/images/$filename`);
await stream.pipe(fs.createWriteStream(pathName));
return
url: `http://localhost:4000/images/$filename`,
;
,
,
;
const server = new ApolloServer(
typeDefs,
resolvers,
);
server.listen().then(( url ) =>
console.log(`???? Server ready at $url`);
);
那么当我上传文件时,它是上传的,但是文件是0kb
like this
【问题讨论】:
【参考方案1】:发生的情况是解析器在文件上传之前返回,导致服务器在客户端完成上传之前做出响应。您需要在解析器中承诺并等待文件上传流事件。
这是一个例子:
https://github.com/jaydenseric/apollo-upload-examples/blob/c456f86b58ead10ea45137628f0a98951f63e239/api/server.js#L40-L41
在你的情况下:
const resolvers =
Query:
hello: () => "Hello world!",
,
Mutation:
fileUpload: async (_, file ) =>
const createReadStream, filename = await file;
const stream = createReadStream();
const path = path.join(__dirname, `/public/images/$filename`);
// Store the file in the filesystem.
await new Promise((resolve, reject) =>
// Create a stream to which the upload will be written.
const writeStream = createWriteStream(path);
// When the upload is fully written, resolve the promise.
writeStream.on("finish", resolve);
// If there's an error writing the file, remove the partially written
// file and reject the promise.
writeStream.on("error", (error) =>
unlink(path, () =>
reject(error);
);
);
// In Node.js <= v13, errors are not automatically propagated between
// piped streams. If there is an error receiving the upload, destroy the
// write stream with the corresponding error.
stream.on("error", (error) => writeStream.destroy(error));
// Pipe the upload into the write stream.
stream.pipe(writeStream);
);
return
url: `http://localhost:4000/images/$filename`,
;
,
,
;
请注意,使用这样的文件名来存储上传的文件可能不是一个好主意,因为以后使用相同文件名的上传会覆盖之前的文件。我不确定如果两个客户端同时上传两个同名文件会发生什么。
【讨论】:
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