GridFS：如何在 <img/> 标签中显示 readstream.pipe(res) 的结果？

Question

我正在使用 MongoDB 和 GridFS 来存储图像。我有这条路线可以从数据库中检索图像：

app.get("/images/profile/:uId", function (req, res) {
let uId = req.params.uId;
console.log(uId)
gfs.files.findOne(
  {
    "metadata.owner": uId,
    "metadata.type": 'profile'
  }
  , function (err, file) {
    if (err || !file) {
      return res.status(404).send({ error: 'Image not found' });
    }
    var readstream = gfs.createReadStream({ filename: file.filename });
    readstream.on("error", function (err) {
      res.send("Image not found");
    });
    readstream.pipe(res);
  });
});

这个 returns 类似的东西 :

�PNG


IHDR���]�bKGD���̿   pHYs
�
�B(�xtIME�  -u��~IDATx��i|TU����JDV�fH�0� :-
H_��M��03`���
(��-�q{U[�m�A��AQ�VZ�ҢbP��S�@K@��CB��|��T�[�=����"U��[��{�s�9�  
�+)@eۿ���{�9���,?�T.S��xL֟x&@�0TSFp7���tʁ���A!_����D�h� 
z����od�G���YzV�?e���|�h���@P�,�{�������Z�l\vc�NӲ�?
n��(�r�.......

看来我正确地获取了png。那么如何在 img 标签中显示它呢？

Answer 1

我已经通过将块转换为 base64 字符串解决了这个问题。然后我传递了如下字符串：

  const readstream = gfs.createReadStream(file.filename);
  readstream.on('data', (chunk) => {
    res.render('newHandlebarFile', { image: chunk.toString('base64') });
  })

我将把手中的值渲染如下：

  <img src="data:image/png;base64,{{ image }}" alt="{{ image }}">

Answer 2

exports.itemimage = function(req,res){
    gfs.files.findOne({ filename: req.params.filename }, (err, file) => {
        res.contentType(file.contentType);
        // Check if image
        if (file) {
          // Read output to browser
          const readstream = gfs.createReadStream(file.filename);
          readstream.pipe(res);
        } else {
            console.log(err);
        }
    });
};

Answer 3

我得到了答案您所要做的就是在 img src

中设置路由类型 URL

app.get('/image/:filename', (req, res) => {
gfs.files.findOne({ filename: req.params.filename }, (err, file) => {
// Check if file
if (!file || file.length === 0) {
  return res.status(404).json({
    err: 'No file exists'
  });
}

// Check if image
if (file.contentType === 'image/jpeg' || file.contentType === 'image/png') {
  // Read output to browser
  const readstream = gfs.createReadStream(file.filename);
    readstream.pipe(res)
} else {
  res.status(404).json({
    err: 'Not an image'
  });
 }
});
});

它奏效了

GridFS：如何在 <img/> 标签中显示 readstream.pipe(res) 的结果？

GridFS : How to display the result of readstream.pipe(res) in an <img/> tag?

html

png

mongodb

gridfs