How to set state of response from axios in react

jordanpowell88 picture jordanpowell88 · Dec 17, 2016 · Viewed 79.3k times · Source

How do I set the state of a get response in axios?

axios.get(response){
    this.setState({events: response.data})
}

Answer

Abdellah Alaoui picture Abdellah Alaoui · Dec 17, 2016

You have a syntax error here. You should try this instead

var self = this;
axios.get('/url')
 .then(function (response) {
   console.log(response);
   self.setState({events: response.data})
 })
.catch(function (error) {
   console.log(error);
});
//the rest of the code
var a = 'i might be executed before the server responds'

There are a few things to note here:

  • axios.get is an asynchronous function which means that the rest of the code will be executed .And when the response of the server arrives, the function passed to then will be executed. The return value of axios.get('url') is called a promise object. You can read more about it here
  • this keyword has a different value depending of where it is called. this in this.setState should refer to the constructor object, and when you call this inside a function, it refers to the window object. That is why i assigned this to the variable self. You can read more about this here

Pro tip:

If you use ES6, you would want to use arrow functions (which don't have their own this) and use this.setState without assigning this to a variable. more about it here

    axios.get('/url')
     .then((response) => {
       console.log(response);
       this.setState({events: response.data})
     })
    .catch((error)=>{
       console.log(error);
    });

Here is a complete example https://codesandbox.io/s/rm4pyq9m0o containing best practices commonly used to fetch data including error handling, try again and loading. This provides a better User experience. You are encouraged to modify the code and play around to get more insights about it.