How can I update this.state with a method?

Question

I'm trying to set new values to a state, but I can't do this with the methods, the state stills the same.

here a declare my state

 this.state = {
    notes: [],
    selected: null
    };
}

using componentDidMount I can update the state

  componentDidMount() {
this.setState({
  notes: this.service.notes,
  selected: {
       title: "vazio",
       text: "vazio"
     }
    });
  }

but when I use this methods to update, the state stills the same

  onSelect(note) {
   this.setState({
   selected: note
    });
  }

You need to call the onSelect method from it's own context by using my for example a lambda, like onSelect="()=> onSelect()". Problem here is the contract where "this" is referring to. See https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/this — n9iels, Mar 21 '20 at 22:07
Yes, it's binding to my note that i'm passing in other component, do u know how can I update the state with that note? — Gabriel Barbosa, Mar 21 '20 at 22:25
https://stackoverflow.com/questions/33973648/react-this-is-undefined-inside-a-component-function — Max, Mar 21 '20 at 22:56

CreativeJoe · Answer 1 · 2020-03-21T23:01:04.577

0

Have you tried?

onSelect = note => {
  this.setState({
  selected: note
 });
}

This gives the onSelect property access to the component scope

edited Mar 21 '20 at 23:01

answered Mar 21 '20 at 22:38

CreativeJoe

andy mccullough · Answer 2 · 2020-03-21T23:05:57.530

0

Try

onSelect = (note) => () => {
   this.setState({
      selected: note
   })
}

It builds a callback function, providing note as an argument

Use it as follows

onSelect={onSelect(note)}

On whatever handler you are using

edited Mar 21 '20 at 23:05

answered Mar 21 '20 at 22:50

andy mccullough

2 Answers2