提取react-native时的Blob数据错误

Question

I am using react native to make a chat-like app. Postman is working properly while doing all the requests I made possible in .NET core api. But when I am trying to fetch from react native it gives the following error:

"null is not an object (evaluating 'blob.data')"

I have tried to look into this issue in different articles but haven't found anything

return new Promise((resolve, reject) => {
            fetch('https://localhost:44305/api/replies', {
                method: 'POST',
                headers: {
                    Accept: 'application/json',
                    'Content-Type': 'application/json',
                },
                body: JSON.stringify(qId)
            })
                .then(res => res.json())
                .then(result => resolve(result))
                .catch(err => reject(err))
        })

I am trying to get a list of answers to a question. Doing it from Postman works fine. I can't find a solution for this error.

I have tried adding return, just like somebody mentioned in a comment before fetch. The result is the same..

Thank you in advance!

Answer 1

I thing your code must something like this:

return fetch(
   'https://localhost:44305/api/replies', {
      method: 'POST',
      headers: {
        Accept: 'application/json',
        'Content-Type': 'application/json',
      },
      body: JSON.stringify(qId)
    }
  )
  .then(res => res.json())
  .then(result => console.log(result))
  .catch(err => console.log(err));

You don't need to create a new promise 'cause fetch does it already.

Note console.log is a void. That means if you continue with thening the null exception will occure again. To solve that use this code at the second then and catch callback method.

console.log(result);
return result;

Answer 2

解决了，问题是我的虚拟设备上没有访问localhost权限，所以我所做的是将IP adress从API中的Debugger选项更改为local ip adress