使用ReactJS

Question

嗨，我想拥有多个TR，并在其中包含多个TD，我想遍历我的compareProperties对象并在render方法中动态创建表，但出现此错误：

  

未捕获的错误：对象作为React子(found: object with keys {id, address, long, lat, cityId, cityDistrict, phone, name, userId, city})无效。如果您打算呈现一个   子代，使用数组代替或使用   来自React附加组件的createFragment（object）。检查渲染方法   比较。

我的数据对象就是这样，我无法更改其结构：

       //this is a samle data, keys in this object can dynamically change elsewhere
       let comparedProperties = {
         id: [1001,1002],
         address: ["abc","def"],
       };

这是我的代码：

   class Comparison extends Component {

render() {
    let comparedProperties = {
        id: [1001, 1002],
        address: ["abc", "def"]
    };

    let comparedItemsData = [];

    for (var key in comparedProperties) {
        if (comparedProperties.hasOwnProperty(key)) {
            let newTR = <tr key={Math.random()} className="compare-table-row">
                <td className="table-item-header">
                    {key}
                </td>
                {comparedProperties[key].map((item) => {
                    return <td key={Math.random()} className="table-item">{item}</td>;
                })}
            </tr>;

            comparedItemsData.push(newTR)
        }
    }

    return (
        <table className="compare-table">
            <tbody>
            {comparedItemsData}
            </tbody>
        </table>
    )
}
     }

    const mapStateToProps = (state) => ({
          ...state
          });
           const mapDispatchToProps = (dispatch) => ({
              actions: bindActionCreators(Actions, dispatch)
          });
          export default connect(
                mapStateToProps,
               mapDispatchToProps
            )(Comparison);

更新答案：

所以我想知道问题出在哪里，但我从反应中得到了更好的错误信息 问题是在我的compareProperties中，数组中有一个导致错误的对象

    let comparedProperties = {"id":[101,102],"estateAgency":[{"id":1},{"id":2}]}

Answer 1

您只需要从map函数中返回td元素。同样也不要指定Math.random()作为react元素的键，因为每次调用render都会分配一个新的键，即使没有任何改变，它也会迫使React重新渲染整个组件。

for (var key in comparedProperties) {
    if (comparedProperties.hasOwnProperty(key)) {
          let newTR = <tr key={key} className="compare-table-row">
                <td className="table-item-header">
                    {key}
                </td>

                //comparedProperties[key] is an array of
               // values that I want to make them as td elements
                { comparedProperties[key].map((item) => {
                    return <td  key={item} className="table-item">{item}</td>;
                })}
            </tr>;


            comparedItemsData.push(newTR)

        }
}

Answer 2

您是否正在尝试做类似的事情？

  render(){

    let comparedProperties = {
      id: [1001, 1002],
      address: ["abc", "def"],
    };

    return (
      <table>

        {Object.keys(comparedProperties).map(key=>(

          <tr key={Math.random()} className="compare-table-row">

            <td className="table-item-header">
              {key}
            </td>

            {comparedProperties[key].map((item) => (
              <td key={Math.random()} className="table-item">{item}</td>
            ))}

          </tr>

        ))}

      </table>
    )
  }

或者，如果您想尝试作为无状态补偿，请在表格中插入：

const ComparedItemsData = ({ comparedProperties }) =>(
    <React.Fragment>
      {Object.keys(comparedProperties).map(key => (
        <tr key={Math.random()} className="compare-table-row">
          <td className="table-item-header">{key}</td>
          {comparedProperties[key].map(item => (
            <td key={Math.random()} className="table-item">
              {item}
            </td>
          ))}
        </tr>
      ))}
    </React.Fragment>
)

const App = ()=>{

  let comparedProperties = {
    id: [1001, 1002],
    address: ["abc", "def"]
  };

  return (
    <table className="compare-table">
      <tbody>
        <ComparedItemsData comparedProperties={comparedProperties}/>
      </tbody>
    </table>
  )
}