com.facebook.react.bridge.readablenativemap cannot be cast to java.lang.string

Question

My code:

const file = {
  uri: this.state.imageSource,
  name: this.state.imageName,
  type: 'image/jpg',
};

const data = new FormData();
data.append('file', file);

fetch(config.server + '/upload', {
  method: 'POST',
  body: data,
})
  .then((res) => res.json())
  .then((responseData) => {
    alert(JSON.stringify(responseData));
  })
  .catch((err) => {
    alert(err);
  });

Without FormData code doesnt display error. What I should do to fix? Debugging on android.

looks like fetch only works with strings, or `JSON.stringify`'ied data , not with `FormData` — Ivan Chernykh, May 31 '18 at 11:22
I had a similar thing just now where I was passing an object to Alert.alert(). I hope that helps someone. — Thomas G Henry LLC, Oct 26 '18 at 04:46

score 24 · Accepted Answer · edited Sep 06 '18 at 14:50

24

The error was because I was passing in the url as an array but it expected a string.

edited Sep 06 '18 at 14:50

MattyK14

2,046
2
17
29

answered Jun 25 '18 at 05:57

kutirie

583
1
4
9

3

Got the same error when passing an object where a string was required. Can be stringified with `JSON.stringify(theobject)`. May not be appropriate in this case of an array of URLs though. – Jeppe Jun 03 '19 at 09:13

score 4 · Answer 2 · answered Sep 11 '19 at 04:52

4

This will resolve the issue : alert(JSON.stringify(data))

answered Sep 11 '19 at 04:52

Rishav Kumar

4,979
1
17
32

score 2 · Answer 3 · answered May 12 '19 at 03:30

2

I was getting this error because my URL was incorrect

answered May 12 '19 at 03:30

Shubham1164

357
6
16

score 0 · Answer 4 · answered May 01 '19 at 13:27

0

In my case I was not running the api server.

answered May 01 '19 at 13:27

anjaneyulubatta505

10,713
1
52
62

score 0 · Answer 5 · answered Dec 23 '21 at 12:39

0

In case this is helpful to someone, I was getting this error:

com.facebook.react.bridge.readableNativeArray cannot be cast to java.lang.boolean

And the issue was me passing a string instead of a boolean to a component.

answered Dec 23 '21 at 12:39

Yuniac

343
3
11

score -1 · Answer 6 · answered Apr 02 '20 at 06:53

I also faced the same issue and the below line of code can be a solution.

var formdata = new FormData();
formdata.append("mobile", phonenumber);

var requestOptions = {
method: 'POST',
body: formdata,
redirect: 'follow'
};

fetch("http://your_url", requestOptions)
.then(response => response.text())
.then(result => console.log(result))
.catch(error => console.log('error', error));

score -2 · Answer 7 · answered Dec 18 '19 at 13:39

-2

react-native link

Use this command to resolve this issue. This worked for me.

Note : Only for react-native < 60.x

answered Dec 18 '19 at 13:39

Gowtham V

27
6

com.facebook.react.bridge.readablenativemap cannot be cast to java.lang.string

7 Answers7