Post request using Fetch not working from componentDidMount

Question

I would very much appreciate your help here pls. I am very new at web dev and in using ReactJS. I am trying to create a login page, using email and password as credentials. The issue is, if i put my fetch function in ComponentDidMount I get a 404 error, but if I take it out of the lifecycle method it connects to the server and i receive the user's details in the terminal - i don't yet know how to get them in the console or in my react app. If you could suggest a way to do that it would be much appreciated. I am trying to get the current user details that logs in.

This is my constructor method:

export default class Login extends React.Component {
  constructor(props){
    super(props);

this.state = {
  user:[],
  email:'',
  password:''
}

For the email and password inputs I have a handleChange function attached to the form: This is the function for the form inputs:

  handleChange = (e) =>{
   this.setState({
    [e.target.name]: [e.target.value]});
 } 

And this is the form:

        <input 
          type= "email"
          name="email"
          placeholder="Email address"
          value={this.state.email}
          onChange={event => this.handleChange(event)}
          required
        />
        <input
          type="password"
          name="password"
          placeholder="Password"
          value={this.state.password}
          onChange={event => this.handleChange(event)}
          required
        />

This is my fetch function in the lifecycle method:

 async componentDidMount(){
   const url = 'http://localhost:3000/login';
   const options = { method: 'POST',
   headers: {
       'Content-Type': 'application/json',
       'Accept': '*/*'
   },
   body: JSON.stringify({email:this.state.email, password:this.state.password})
   };

   const response = await fetch(url,options);
   let data = response.json();
   this.setState({user: data.results})
}

At this stage I get a 404 error in my console: ( POST http://localhost:3000/login 404 (Not Found) and in the terminal I get this error:

data:: {}
user:: []
user.length:: 0
TypeError: Cannot read property 'password' of undefined
at authenticateUser (/Users/noir/Documents/Dana/work/SocialCats/backend/controllers/login.js:16:16)
at processTicksAndRejections (internal/process/task_queues.js:97:5)

If i switch to Postman it works without problems, on the same url.

If I take my fetch function out of the lifecycle method, then it works to authenticate the user and I get the users details in my terminal. Any idea why is this happening? Every help is greatly valued as I am quite stuck here. Thanks :)

Answer 1

Do the API call on when the user submits the form. At componentDidMount, the user has not entered email and password. Thus, your apiCall throws an error.

class Login extends React.Component {

  handleSubmit = (e) => {
      e.preventDefault();
      // do your API call here.
  }

  render() {
   return (
     <form onSubmit={handleSubmit}>
       /** all the other input tags */
     </form>
   )
  }
}