CODEWITHSUNDEEP
javascriptreactjs
N Sharma
N Sharma

Reputation: 34507

How to save data in an array inside state in react js

I have TextField and FlatButton inside the Dialog. I want to save complete task list in an array which I defined in a state.

this.state = {
  open: false,
  todos: [{ id: -1, text: "", completed: false }],
  notetext: ""
};

I am able to get text of TextField from the state. I want to save task in an array on clicking of FlatButton. I have handleCreateNote function which is attached on tap on FlatButton.

I don't know what is the way to add task in an array. Can anyone help me what is the way in the react ?

const AppBarTest = () =>
  <AppBar
    title={strings.app_name}
    iconClassNameRight="muidocs-icon-navigation-expand-more"
    style={{ backgroundColor: colors.blue_color }}
  />;

class App extends Component {
  constructor(props) {
    injectTapEventPlugin();
    super(props);
    this.state = {
      open: false,
      todos: [{ id: -1, text: "", completed: false }],
      notetext: ""
    };
    this.handleChange = this.handleChange.bind(this);
  }

  handleOpen = () => {
    this.setState({ open: true });
  };

  handleClose = () => {
    this.setState({ open: false });
  };

  handleCreateNote = () => {
    console.log(this.state.notetext);
  };

  handleChange(event) {
    this.setState({ [event.target.name]: event.target.value });
  }

  render() {
    return (
      <MuiThemeProvider>
        <div>
          <AppBarTest />
          <FloatingActionButton
            style={styles.fab}
            backgroundColor={colors.blue_color}
            onTouchTap={this.handleOpen}
          >
            <ContentAdd />
          </FloatingActionButton>
          <Dialog
            open={this.state.open}
            onRequestClose={this.handleClose}
            title={strings.dialog_create_note_title}
          >
            <TextField
              name="notetext"
              hintText="Note"
              style={{ width: "48%", float: "left", height: 48 }}
              defaultValue={this.state.noteVal}
              onChange={this.handleChange}
            />

            <div
              style={{
                width: "4%",
                height: "48",
                backgroundColor: "red",
                float: "left",
                visibility: "hidden"
              }}
            />

            <FlatButton
              label={strings.create_note}
              style={{ width: "48%", height: 48, float: "left" }}
              onTouchTap={this.handleCreateNote}
            />
          </Dialog>

        </div>
      </MuiThemeProvider>
    );
  }
}

export default App;

Upvotes: 1

Views: 17330

Answers (2)

xdaoo
xdaoo

Reputation: 11

you can use concat to create a new array:

this.setState({
    todos: [].Concat(this.state.todos, {id, text,  complete})
})

Upvotes: 1

Mayank Shukla
Mayank Shukla

Reputation: 104529

First create a copy of existing state array, then use array.push to add a new data, then use setState to update the state array value.

Like this:

handleCreateNote = () => {
    let todos = [...this.state.todos];   //creating the copy

    //adding new data
    todos.push({
        id: /*unique id*/,
        text: this.state.notetext,
        completed: false
    });

    //updating the state value
    this.setState({todos});
};

Check this answer for details about "..." --> What do these three dots in React do?

MDN: Spread Operator

Update:

Instead of spread operator you can also use slice(), that will also return a new array, the key point is we need to create a copy of state array (before doing any change) by using any method.

Check this snippet:

let a = [{key: 1}, {key: 2}];

let b = [...a];

console.log('b', b);

Upvotes: 7

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