Question

我只需要从json文件中获取单个数据，我正在使用lodash .groupBy和.filter，但只会抛出错误的结果

let insightAverageThroughput = [{
    "insight": "wahahahah",
    "reportMonth": "June 2018",
    "project": "Cambridge Core Dashboard"
  },
  {
    "insight": "aaaaaaa",
    "reportMonth": "February 2018",
    "project": "coreadmin"
  }
];

function filterInsights(data, month, project) {
  let grouped = _.groupBy(data, z => z.project == project)
  console.log(month)
  console.log(project)
  console.log(grouped)
  let filtered = _.filter(grouped[project], x => x.reportMonth == month)
  console.log(filter)
  return filtered.length > 0 && filtered[0].insight;
}

Answer 1

您应该groupBy仅按项目而不按谓词：

  let grouped = _.groupBy(data, z => z.project)

Answer 2

使用groupBy，所有数据将按一个项目进行分组，并使用filter返回满足条件reportMonth === month的所有项目。

还请注意我如何使用groupBy。您应该传递一个值，而不是条件：

_.groupBy(data, 'project')

这是代码：

let insightAverageThroughput = [{
    "insight": "wahahahah",
    "reportMonth": "June 2018",
    "project": "Cambridge Core Dashboard"
  },
  {
    "insight": "aaaaaaa",
    "reportMonth": "February 2018",
    "project": "coreadmin"
  }
];

function filterInsights(data, month, project) {
  const grouped = _.groupBy(data, 'project')
  const filteredItems = grouped[project].filter(({ reportMonth }) => reportMonth === month)
  
  return { [project]: filteredItems }
}

console.log(filterInsights(insightAverageThroughput, 'February 2018', 'coreadmin'))

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/1.2.1/lodash.min.js"></script>

可以在ES6中实现相同的逻辑（无需外部库）。仅使用reduce的方式如下：

let insightAverageThroughput = [{
    "insight": "wahahahah",
    "reportMonth": "June 2018",
    "project": "Cambridge Core Dashboard"
  },
  {
    "insight": "aaaaaaa",
    "reportMonth": "February 2018",
    "project": "coreadmin"
  }
];

function filterInsights(data, month, project) {
  return data.reduce((accumulator, item) => { 

    if (item.project === project && month === item.reportMonth) {
      accumulator[project].push(item)
    }
    
    return accumulator
  } , { [project]: [] })
}

console.log(filterInsights(insightAverageThroughput, 'February 2018', 'coreadmin' ))

如何使用groupby从JSON获取数据以及如何使用lodash进行过滤

2 个答案: