如何从 SharePoint 列表项中获取数组中的总数

Question

我正在使用 Reactjs 创建一个 spfx Web 部件。我有一个函数从 SharePoint 列表中获取一组项目，其中包括“小时”的数字列。我需要计算所有返回的小时数，但不知道如何计算。

我觉得我错过了一些简单的东西，但我已经经历了各种循环，由于某种原因我无法让它工作。我已确认我正在从“小时”列获取数据。

我还将声明“我是 spfx 的新手并做出反应”。 :) TIA 寻求帮助！

private readItem(): void {
  this.props.spHttpClient.get(`${this.props.siteUrl}/_api/web/lists/getbytitle('Time Off')/items?$select=Title,Id,Hours`,
    SPHttpClient.configurations.v1,
    {
      headers: {
        'Accept': 'application/json;odata=nometadata',
        'odata-version': ''
      }
    }).then((response: SPHttpClientResponse): Promise<ITimeOffItem[]> => {
      return response.json();
    })
    .then((item: ITimeOffItem[]): void => {

      console.log(item); //the data is here including Hours

      this.setState({
        items: item,
        hoursTotal: //????How do I get the sum of "Hours" and assign it to a number in state
      });

    });
}

Answer 1

创建一个函数来循环遍历项目并添加小时

function countHours(items) {
  if (!items) {
    return 0;
  }

  let total = 0;

  for (let i = 0; i < items.length; i++) {
    total += items[i].Hours;
  }

  return total;
}

const item = [
  { Id: 25, Title: "Comp Time", Hours: 6, ID: 25 },
  { Id: 26, Title: "Comp Time", Hours: 5, ID: 26 },
  { Id: 27, Title: "Work from Home", Hours: 3, ID: 27 },
  { Id: 28, Title: "Comp Time", Hours: 7, ID: 28 },
  { Id: 29, Title: "Work from Home", Hours: 8, ID: 29 },
  { Id: 30, Title: "Holiday", Hours: 8, ID: 30 },
  { Id: 31, Title: "Work from Home", Hours: 32, ID: 31 }
];

console.log(countHours(item));

像这样使用它

this.setState({
    items: item,
    hoursTotal: countHours(item)
});

你也可以使用reduce

const item = [
  { Id: 25, Title: "Comp Time", Hours: 6, ID: 25 },
  { Id: 26, Title: "Comp Time", Hours: 5, ID: 26 },
  { Id: 27, Title: "Work from Home", Hours: 3, ID: 27 },
  { Id: 28, Title: "Comp Time", Hours: 7, ID: 28 },
  { Id: 29, Title: "Work from Home", Hours: 8, ID: 29 },
  { Id: 30, Title: "Holiday", Hours: 8, ID: 30 },
  { Id: 31, Title: "Work from Home", Hours: 32, ID: 31 }
];
const sum = item.reduce(function(a, b) { return a + b.Hours; }, 0);

console.log(sum)

Answer 2

在不知道数据结构是什么样子的情况下很难回答这个问题，但如果您尝试对一组数字求和，则可以使用 reduce。

const hours = [7, 5, 3, 1, 7]

const totalHours = hours.reduce((accumulator, hour) => accumulator + hour)