How to post multipart/form-data with node.js superagent

Question

I am trying to send the content-type in my superagent post request to multipart/form-data.

var myagent = superagent.agent();

myagent
  .post('http://localhost/endpoint')
  .set('api_key', apikey)
  .set('Content-Type', 'multipart/form-data')
  .send(fields)
  .end(function(error, response){
    if(error) { 
       console.log("Error: " + error);
    }
  });

The error I get is: TypeError: Argument must be a string

If I remove the:

.set('Content-Type', 'multipart/form-data')

I don't get any error but my back end is receiving the request as content-type: application/json

How can I force the content type to be multipart/form-data so that I can access req.files()?

Answer 1

First, you do not mention either of the following:

.set('Content-Type', 'multipart/form-data')

OR

.type('form')

Second, you do not use the .send, you use .field(name, value).

Examples

Let's say you wanted to send a form-data request with the following:

• two text fields: name and phone
• one file: photo

So your request will be something like this:

superagent
  .post( 'https://example.com/api/foo.bar' )
  .set('Authorization', '...')
  .accept('application/json')
  .field('name', 'My name')
  .field('phone', 'My phone')
  .attach('photo', 'path/to/photo.gif')

  .then((result) => {
    // process the result here
  })
  .catch((err) => {
    throw err;
  });

And, let's say you wanted to send JSON as a value of one of your fields, then you'd do this.

try {
  await superagent
         .post( 'https://example.com/api/dog.crow' )
         .accept('application/json')
         .field('data', JSON.stringify({ name: 'value' }))
}
catch ( ex ) {
    // .catch() stuff
}

// .then() stuff...