反应。 如何将setState中的键与数组索引一起使用？

Question

So, this is my code. I have a simple question just about how I can use the state element with indexin key ? In this case I need to set the different values for different data index elements.

import React, { Component } from 'react';
import {Doughnut} from 'react-chartjs-2';

class Chart extends Component {
    constructor(props) {
        super(props);

        this.state = {
            labels: ["All", "Done", "Active"],
            datasets: [{
                label: "Todos",
                backgroundColor: 'grey',
                borderColor: 'green',
                data: [0, 0, 0]
            }]
        };
    }

    getTodosList = (todos) => {
        const all = [];
        const active = [];
        const done = [];

        todos.filter(todo => {
            if (todo.status === 'active') {
                active.push(todo);
            } else if (todo.status === 'all') {
                all.push(todo);
            } else if (todo.status === 'done') {
                done.push(todo);
            }
        });

        this.setState({
            datasets[0].data[0]: all, // error
            datasets[0].data[1]: active, // error
            datasets[0].data[2]: done // error
        });
    }

Answer 1

It's simple:

this.setState({
    datasets: [...this.state.datasets,
        {
            data: [all.length, active.length, done.length]
        }
    ]
});

Start to think like Redux think. Use pure functions. It's will help you. Also I understand based on your starts data - you probably need to use the length of your items ...

Answer 2

The setState function doesn't know which object it has to replace with your code. You're also not accessing the datasets variable properly, it should be this.state.datasets . You could do something like:

let datasets = this.state.datasets.slice();
datasets[0].data[0] = all;
datasets[0].data[1] = active;
datasets[0].data[2] = done;
this.setState({datasets});