.map array by its objects keys then .map 每个键的值

Question

如果我有一个像这样的对象数组：

[{"name":"chair","type":"metal"},{"name":"chair","type":"wood"},{"name":"table","type":"plastic"},...]

我怎样才能映射它 returns:

<h3>chair</h3>
metal
wood

<h3>table</h3>
plastic

ecc.

我试过的是：

return (
   <>
    {Object.values(myarray.reduce( (c, e) => {
        if (!c[e.name]) c[e.name] = e;
        return c;
    }, {})).map((title, index) => (
        <div key={index}>
            <h3>{title}</h3>
            {myarray.filter(one => one.name === title)
            .map((item, i) => (
                <div key={i}>{item.type}</div>
            ))}
        </div>
    ))}
</>
)

但它抛出

Error: Objects are not valid as a React child (found: object with keys {name, type}). If you meant to render a collection of children, use an array instead.

Answer 1

这是分组的简单逻辑

var data= [{"name":"chair","type":"metal"},{"name":"chair","type":"wood"},{"name":"table","type":"plastic"}]

var groupBy = (xs, f) => {
        return xs.reduce((r, v, i, a, k = f(v)) => ((r[k] || (r[k] = [])).push(v), r), {});
    };

var groupData = groupBy(data, (d) => d.name);
$.each(groupData,function(key,val){ 
  $('#pnlData').append("<h3>"+key+"</h3>")
  $.each(val,function(skey,sval){
  $('#pnlData').append("<span>"+sval.type+"</span> <br/>")
  })
})

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div id="pnlData"> </div>

Answer 2

这是一个示例代码

const a = [{"name":"chair","type":"metal"},{"name":"chair","type":"wood"},{"name":"table","type":"plastic"}];

const b = {};
a.map(row => {
    b[row.name] = b[row.name] || []
    b[row.name].push(row.type) 
})

console.log(b) // you can check results here...

// result: {"chair":["metal","wood"],"table":["plastic"]}

Answer 3

Reduce是你需要的功能：

const things = [{name: 'chair', type: 'metal'}, ...]

things.reduce((a, _) => {
    a[_.name] = a[_.name] || [] // make array for this thing
    a[_.name].indexOf(_.type) < 0 && a[_.name].push(_.type) // add type if not already present
    return a
}, {})

Answer 4

您可以使用reduce 函数按名称对所有条目进行分组。然后你可以使用 Object.keys 或 Object.values 来获取条目名称或类型。

array.reduce((reducer, current) => {
    if (!reducer[current.name]) {
        reducer[current.name] = [];
    }

    reducer[current.name].push(current.type);
    return reducer;
}, {})

// result : { chair: ["wood", "metal"], table: ["plastic"] }

Answer 5

如果可能更改数据 structure/array 对象。我认为如果它看起来像这样会更容易。您的新数组：

const myArray = [
    {
      "name":"chair",
      "types":["metal", "wood"]
    },
    {
      "name":"table",
      "types":["plastic"]
    }
  ]

  //in your ui code would be 
  myArray.map(item => {
    return <div>
        <h3>item.name</h3>
        {item.types.map(type => <div>{type}</div>)}
    </div>
  })

Answer 6

您可以将数据数组简化为一个对象，然后使用该对象进行渲染。

 // reducer

   let data = [
    { name: "chair", type: "metal" },
    { name: "chair", type: "wood" },
    { name: "table", type: "plastic" }
  ];

  let data2 = data.reduce((xuu, val) => {
    xuu[val.name] = xuu[val.name] || [];

    xuu[val.name].push(val.type);

    return xuu;
  }, {});

 // render

  {Object.keys(data2).map((key, index1) => {
    return (
      <div key={index1}>
        <h3>{key}</h3>
        {data2[key].map((val, index2) => {
          return <div key={index2}>{val}</div>;
        })}
      </div>
    );
  })}

你可以玩玩 my sandbox

.map array by its objects keys then .map 每个键的值

.map array by its objects keys then .map each key for values

javascript

reactjs

reduce

array.prototype.map