Mongoose 设置两次标头和/或未正确处理回调-导致错误[ERR\u HTTP\u headers\u SENT]
我用这段代码获得了预期的图像，但它没有显示在我的pug模板中，而是显示在浏览器devtools控制台中（我希望这是有意义的），而且似乎我正在尝试设置两次标题。我的代码生成[ERR\u HTTP\u HEADERS\u SENT]，如下所示 我已经阅读了许多关于这个问题的问题，包括这个问题的彻底分解： 我认为实际发生的是我没有正确处理回调，但我不确定 我真的很挣扎，需要一点帮助来指出我哪里出了问题 route.js：Mongoose 设置两次标头和/或未正确处理回调-导致错误[ERR\u HTTP\u headers\u SENT],mongoose,callback,http-headers,gridfs-stream,Mongoose,Callback,Http Headers,Gridfs Stream,我用这段代码获得了预期的图像，但它没有显示在我的pug模板中，而是显示在浏览器devtools控制台中（我希望这是有意义的），而且似乎我正在尝试设置两次标题。我的代码生成[ERR\u HTTP\u HEADERS\u SENT]，如下所示 我已经阅读了许多关于这个问题的问题，包括这个问题的彻底分解： 我认为实际发生的是我没有正确处理回调，但我不确定 我真的很挣扎，需要一点帮助来指出我哪里出了问题 route.js： router.get('/issue/filedisplay/:id', is
router.get('/issue/filedisplay/:id', issue_controller.file_display);
// controller.js
exports.file_display = function(req, res) {
gfs.files.findOne(
{ _id: mongoose.Types.ObjectId(req.params.id) },
(err, file) => {
//res.contentType(file.contentType);
// Check if file
if (!file || file.length === 0) {
return res.status(404).json({
err: 'No file exists',
});
}
const readstream = gfs.createReadStream(file._id);
readstream.pipe(res);
readstream.on('close', () => {
res.render('filedisplay', {
title: 'Display Image',
file: file._id,
});
});
//return res.json(file);
//return res;
}
);
};
//-filedisplay.pug
extends layout
block content
h1= title
p Display Image
div
img.image(src="/list/issue/filedisplay/" + file alt="")
Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client
at ServerResponse.setHeader (_http_outgoing.js:482:11)
at ServerResponse.header (/home/don/dev/sandbox/fileupload-ex/file-upload-gridfs/node_modules/express/lib/response.js:771:10)
at ServerResponse.send (/home/don/dev/sandbox/fileupload-ex/file-upload-gridfs/node_modules/express/lib/response.js:170:12)
at done (/home/don/dev/sandbox/fileupload-ex/file-upload-gridfs/node_modules/express/lib/response.js:1008:10)
at Object.exports.renderFile (/home/don/dev/sandbox/fileupload-ex/file-upload-gridfs/node_modules/pug/lib/index.js:421:12)
at View.exports.__express [as engine] (/home/don/dev/sandbox/fileupload-ex/file-upload-gridfs/node_modules/pug/lib/index.js:464:11)
at View.render (/home/don/dev/sandbox/fileupload-ex/file-upload-gridfs/node_modules/express/lib/view.js:135:8)
at tryRender (/home/don/dev/sandbox/fileupload-ex/file-upload-gridfs/node_modules/express/lib/application.js:640:10)
at Function.render (/home/don/dev/sandbox/fileupload-ex/file-upload-gridfs/node_modules/express/lib/application.js:592:3)
at ServerResponse.render (/home/don/dev/sandbox/fileupload-ex/file-upload-gridfs/node_modules/express/lib/response.js:1012:7)
at /home/don/dev/sandbox/fileupload-ex/file-upload-gridfs/app.js:82:7
at Layer.handle_error (/home/don/dev/sandbox/fileupload-ex/file-upload-gridfs/node_modules/express/lib/router/layer.js:71:5)
at trim_prefix (/home/don/dev/sandbox/fileupload-ex/file-upload-gridfs/node_modules/express/lib/router/index.js:315:13)
at /home/don/dev/sandbox/fileupload-ex/file-upload-gridfs/node_modules/express/lib/router/index.js:284:7
at Function.process_params (/home/don/dev/sandbox/fileupload-ex/file-upload-gridfs/node_modules/express/lib/router/index.js:335:12)
at next (/home/don/dev/sandbox/fileupload-ex/file-upload-gridfs/node_modules/express/lib/router/index.js:275:10)
这个问题已经结束。它没有被解析，代码仍然被破坏。在上述控制器代码中，我真正需要的是以下各项：
readstream.pipe(res);