Question 49338 in Javascript Question posted in
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Trying to write to a external json file using fs and express – Javascript

I’m trying to write an object to a JSON, when passing the data through to the server I keep receiving this error and I cannot seem to find a solution to fix it…

Here is my code

APP.post('/api', (req, res) => {
    
    const data = req.body;
    console.log(data);

    try {
        fs.writeFileSync(PATH, data);
    } catch(err) {
        console.log(err)
    }

    res.send("Updated");
});

The object looks like the following i.e. req.body

{
  name: '',
  currentStats: {
    stat: 0,

  },
  trackStats: { history: 0 }
}

The error in question

TypeError [ERR_INVALID_ARG_TYPE]: The "data" argument must be of type string or an instance of Buffer, TypedArray, or DataView. Received an instance of Object

Tags:

2

Answers


  1. 0

    fs.writeFileSync writes data in binary format, and it expects a buffer or a string as the second argument. Thus you need to convert your JavaScript object to a JSON string using JSON.stringify()

    fs.writeFileSync(PATH,JSON.stringify(data));

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  2. 0

    that error is happening because fs.writeFileSync expects the data argument to be a string, Buffer, TypedArray, or DataView.

    In your case, you’re trying to write an object (req.body) directly to the file, which is not supported.

    To fix this, convert the req.body into a JSON string with JSON.stringify() before writing it to the file. Here’s how you should do it:

    fs.writeFileSync(PATH, JSON.stringify(data));

    With this change, you should be able to write the object to the JSON file without any issues.

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