What could be the reason for my FormData object being consistently devoid of content?

I am attempting to populate formData with data using the following method:

params = {'code': 'h1'}
const formData: FormData = new FormData();
formData.append('parameters', JSON.stringify(params));

Once I attempt to access the data from formData like this: formData['parameters'], it comes back as undefined and formData.entries.length is 0. I have checked various sources and they all suggest that this is the correct approach. Can anyone advise on what might be going wrong?

Many thanks.

typescriptform-data

Answer №1

It seems that your FormData object is not empty, but the way you are accessing the data after appending it may be incorrect.

In my experience, the following code snippet works properly:

const params = {'code': 'h1'}
const formData = new FormData();
formData.append('parameters', JSON.stringify(params));

for (const entry of formData.entries())
{
    document.write(entry);
}

A couple of side notes to consider:

  • Since formData.entries() returns an iterator object, there is no length property.
  • There is also no indexer like [] defined. To retrieve values, you need to use the get() method as demonstrated by Daniel Beck in his answer.

Answer №2

The formData object should be declared correctly (edit: for javascript. The question wasn't originally tagged with typescript, which I'm not familiar enough with)

const params={'code': 'h1'}
const formData = new FormData()
formData.append('parameters', JSON.stringify(params))
// confirm:
console.log(formData.get('parameters'))

...however, if you intend to set multiple parameters on formData instead of just one named "parameters", consider the following approach:

const params={
  'code': 'h1',
  'foo': 'bar'
}

const formData = new FormData()
Object.keys(params).forEach((k) => {
  formData.append(k, params[k])
})

// confirm:
console.log(formData.get('code'))
console.log(formData.get('foo'))

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