calling two async functions one after another in .post function Node.JS

Question

I want to receive an image from a client, convert it into text and then delete the image once it's converted. I'm using the following code:

app.post('/upload', (req,res)=>{
    const myFile = req.files.file;
    myFile.mv(`D:/web_projects/react-express-mongodb-template/server/pictures/${myFile.name}`)
    
    let img = `D:/web_projects/react-express-mongodb-template/server/pictures/${myFile.name}`
    convert(img);
    remove(img)
    
})
app.listen(5000, () => {
    console.log('server is running at port 5000');
})
async function convert(img){
  const worker = createWorker();
    
  console.log(worker)
  await worker.load();
  await worker.loadLanguage('eng');
  await worker.initialize('eng');
  const { data: { text } } = await worker.recognize(img);
  console.log(text);
  await worker.terminate();
    
}
async function remove(path){
  try {
    fs.unlink(path)
  } catch(err) {
    console.error(err)
  }
}

So in the post method I call the convert function and then remove but remove gets executed first and so convert function results in error. Is there a way to handle this issue?

Yes, but what is its definition? Are you sure those worker methods return promises? — trincot
– trincot, Commented Mar 8, 2021 at 18:39
Tbh I don't know the definition but I'm sure it returns promises as I found this code on official github page of tesseract.js — bearthum
– bearthum, Commented Mar 8, 2021 at 18:44

trincot · Accepted Answer · 2021-03-08 15:25:49Z

1

As convert is an async function, and thus returns a promise, replace:

convert(img);
remove(img)

With:

convert(img).then(() => remove(img));

However, this assumes that all awaited worker method calls in convert return promises. If this is not the case, and they run asynchronous code, then actually convert will not properly await those, and you should first promisify them.

edited Mar 8, 2021 at 15:25

answered Mar 8, 2021 at 15:19

trincot

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