setState到對象內部的Array

Question

這就是我的Chart組件中的狀態。 我從我的數據庫（帶有componentDidMount）中獲取城市數據和關注者數據，我想將城市設置為chartData內的lables數組，並將關注者（包含數字的數組）設置為數據數組，但是我無法獲取它完成。 最好的方法是什么？

state = {
  chartData: {
    labels: [here],
    datasets: [
      {
        label: 'Population',
        data: [here],
        backgroundColor: [
          'rgba(255, 99, 132, 0.6)',
          'rgba(54, 162, 235, 0.6)',
          'rgba(255, 206, 86, 0.6)',
          'rgba(75, 192, 192, 0.6)',
          'rgba(153, 102, 255, 0.6)',
          'rgba(255, 159, 64, 0.6)',
          'rgba(255, 99, 132, 0.6)'
        ]
      }
    ]
  }
}

Answer 1

授予您要在其中添加關注者的datasets數組中只有一個對象，您可以像這樣更新狀態：

 class App extends React.Component { state = { chartData: { labels: [], datasets: [ { label: "Population", data: [], backgroundColor: [ "rgba(255, 99, 132, 0.6)", "rgba(54, 162, 235, 0.6)", "rgba(255, 206, 86, 0.6)", "rgba(75, 192, 192, 0.6)", "rgba(153, 102, 255, 0.6)", "rgba(255, 159, 64, 0.6)", "rgba(255, 99, 132, 0.6)" ] } ] } }; componentDidMount() { setTimeout(() => { this.setState(prevState => { const cities = ["foo", "bar", "baz"]; const followers = [1, 2, 3]; return { chartData: { ...prevState.chartData, labels: cities, datasets: [ { ...prevState.chartData.datasets[0], data: followers } ] } }; }); }, 2000); } render() { return <div>{JSON.stringify(this.state)}</div>; } } ReactDOM.render(<App />, document.getElementById("root")); 

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