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javascript - Reactjs 遇到两个孩子使用相同的键，`NaN`。键应该是唯一的

问题描述

我尝试了不同的方法来消除遇到两个孩子用相同的钥匙，NaN。键应该是唯一的，这是部分日志：

in DynamicFields (at TableHeader.js)
in th (at TableHeader.js)
in TableHeader

这基本上是 TableHeader.js 组件的这一点，完整的代码粘贴在此页面的下方：

return (
        <th key={cleanTitle + - + index}
            ref={(th) => th = th}
            style={{width:width}}
            data-col={cleanTitle}
         >

         <span className="header-cell" key={index*11}>{title} </span>
         <DynamicFields key={header.index+title} parentIndex={(index + 3) + title} />
       </th>
      );

我已经阅读了有关 keys 和 reactjs 的讨论 ，并遵循了它，但错误仍然没有停止。

以下是渲染数据表所涉及的 3 个组件：

MyDatatable.js 
import React from "react";
import TableHeader from "./TableHeader";

const MyDatatable = (props) => {
  columnHeaders =  [
        {title: "Id" , accessor: 'id' , index: 0},
        {title: "Name" , accessor: 'name', width: "300px", index: 2}
        ]
        
   rowData = [
      {id: 1, name: 'a', age: 29, qualification: 'B.com', rating: 3, profile: 'ps'},
      {id: 2, name: 'b', age: 35, qualification: 'B.Sc', rating: 5, profile: 'h'}
   ]
        
  const [headers, setHeaders] = React.useState(columnHeaders);

  const [data, setData] = React.useState(rowData)
  
  const  renderContent = () => {
    let contentView = data.map((row, rowIdx) => {
    let id = row[keyField];
    let tds = headers.map((header, index) => {
    let content = row[header.accessor];

    return (
      <td key={index} data-id={id} data-row={rowIdx}>
        {content}
      </td>
     );
   });
        
   return (
     <tr key={rowIdx}>
       {tds}
     </tr>
    );
            //
  }); //closes contentView variable

 return contentView;
}

const renderTable = () => {
  let title = props.title || "DataTable";
  let contentView = renderContent();
          
  return (
    <table className="data-inner-table table-responsive">
      <caption className="data-table-caption">
        {title}
      </caption>
      <thead>
        <tr>
          <TableHeader headers={headers} />
        </tr>
      </thead>

      <tbody>
        {contentView}
      </tbody>
    </table>
  )}  

  return (
    <React.Fragment>
      <div className={props.className}>
        {renderTable() }
      </div>
    </React.Fragment>
  )
}
表头.js 
import React from "react";
import DynamicFields from "../DynamicFields";

const TableHeader = (props) => {
  let FieldTypes = ["text", "dropdown"];
  
  const renderTableHeader = () => {

    headers.sort((a, b) => {
      if (a.index > b.index) return 1;
      return -1
    });

    const headerView = headers.map((header, index) => {
      let title = header.title;
      let cleanTitle = header.accessor;
      let width = header.width;

      return (
        <th key={cleanTitle + - + index}
            ref={(th) => th = th}
            style={{width:width}}
            data-col={cleanTitle}
         >

         <span className="header-cell" key={index*11}>{title} </span>
         <DynamicFields key={header.index+title} parentIndex={(index + 3) + title} />
       </th>
      );

  } );

    return headerView;
  }

  return(
    <React.Fragment>
     {renderTableHeader()}
    </React.Fragment>
  )
}
动态字段.js 
import React, { useState, useEffect, useRef } from "react"

const DynamicFields = (props) => {
  const  optionsHash =  ['Checkbox', 'Dropdown', 'boolean', 'Single line text'];

  const [showDynamicField, setShowDynamicField ] = useState(false);

  // const dropdownRef = useRef();
  
  
   const handleShowDynamicField = (event) => {
     setShowDynamicField(!showDynamicField);
   };

  return (
    <React.Fragment>
      <i className="bi bi-chevron-compact-down" onClick={handleShowDynamicField}></i>

     {showDynamicField &&
       optionsHash.map( (val, idx) => {
                return(
                 <li key={val-idx}  value={val} className="dropdown-item"> {val} </li>
                )
       })
     }
    </React.Fragment>
  )
}

标签： javascriptreactjsreact-key-index

解决方案

-是减法运算符，这将导致key={val-idx}(string - number => NaN) 出现问题。
大概您想使用 - 作为分隔符，因此您将其用作字符串：key={val + '-' + idx}或 key={`${val}-${idx}`}

在这种情况下，由于optionsHash具有所有唯一字符串，您可以只使用key={val}.

起作用的原因key={cleanTitle + - + index}是因为它评估为cleanTitle + (- +index)，将负数添加到允许的字符串（但令人困惑）。

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