I am having trouble processing the name of a file I upload to my server. I use formidable to parse a form and save the data to my database. I then want to return the filename the id I get from my database to the client.

My api route (without error handling etc) calls uploadFile() when it receives a POST request

export default async function handler(req, res) {
      await uploadFile(req, res);
      break;
}

In uploadFile I process the form and send the response back to the client without the insertId everything works. But I can´t figure out how to wait for my db response or where to call it.

export async function uploadFile(req, res) {
    const form = new IncomingForm({
      multiple: false,
    });

    await form.parse(req).on("file", (name, file) => {

      // This wont work since I cant await inside the await call
      const insertId = await writeToDb("INSERT into [...]")

      res.status(200).json({filename: file.originalFilename, id:insertId })
    });
}

It feels like I am missing a general concept about async programming here. Any help that leads me in the right direction is greatly appreciated!

CodePudding user response：

You can use await if you make the handler function async:

form.parse(req).on("file", async (name, file) => {
  //                       ^^^^^
  const insertId = await writeToDb("INSERT into [...]")
  res.status(200).json({filename: file.originalFilename, id:insertId })
});

There are some caveats:

• this only works if your uploads consist of only one file (but I assume they do, because you send back a response after processing the first file)
• uploadFile will return before the response it sent back; judging by the implementation of handler(), that won't be an issue in this situation though.