How to get JSON data from fetch (react-native)

Question

I'm writing small app for iPhone using react native. I'm trying to fetch JSON data from a website using fetch. Like in the example:

   function status(response) {
  if (response.status >= 200 && response.status < 300) {
    return response
  }
  throw new Error(response.statusText)
}

function json(response) {
  return response.json()
}


fetch('/users', {
  method: 'post',
  headers: {
    'Accept': 'application/json',
    'Content-Type': 'application/json'
  },
  body: JSON.stringify({
    name: 'Hubot',
    login: 'hubot',
  })
}).then(status)
  .then(json)
  .then(function(json) {
    console.log('request succeeded with json response', json)
  }).catch(function(error) {
    console.log('request failed', error)
  })

Everything works fine but I need to use that data later. When I try to assign it to some variable in json function, I get "Request error" and after that get the data (correctly). What's the best practise to get that data and have it in some variable to use it later?

Answer 1

Firstly, as you know, each request returns a header and a body

When we use fetch a default response that is headers request. If we need to body of request, that's enough response.json()

return fetch(url,{
  method: 'POST',//GET and ...
  headers:{
      Accept: 'application/json',
      'Content-Type': 'application/json',
  },
  body: JSON.stringify({
      elm: "elm" //is fake
  })
 })
 .then((response)=>response.json()) //   <------ this line 
 .then((response)=>{
   return response ;
 });

And if the body of your request is html dom Just use this response.text()

And if you want to return your header no need to do anything, Just add this line .then((response)=>response.json())

Answer 2

I did it like this. I displayed the response on console. You can store the response data in your state variable or in local storage as you want.

  doSignUp() {

     console.log("inside post api");
     fetch('your API URL', {
     method: 'POST',
     headers: {
                  'Accept': 'application/json',
                  'Content-Type': 'application/json',

                },


      body: JSON.stringify({
      password: this.state.password,
      email:this.state.email,
      name: this.state.firstname,
      last_name :this.state.last_name,
      mobile:this.state.mobile,
      ssn:"2222222"

     })
      }).then((response) => response.json())
        .then((responseData) => {
                                 console.log("inside responsejson");
                                 console.log('response object:',responseData)

         }).done();
     }