使用lodash应用多个分组

Question

我想通过两个属性（名称和地址2）对JSON数组进行分组，然后将其减少。这是当前JSON：

{ 
    "clientId": "FOO", 
    "name": "John Doe", 
    "address1": "London", 
    "address2": "1 High Street", 
    "invoiceNumber": "1234", 
    "itemDescription": "Item 1", 
    "itemQuantity": 1 
}, 
{ 
    "clientId": "BAR", 
    "name": "John Doe", 
    "address1": "London", 
    "address2": "1 Oxford Street", 
    "invoiceNumber": "0987", 
    "itemDescription": "Item 2", 
    "itemQuantity": 1 
}, 
{ 
    "clientId": "FOO", 
    "name": "John Doe", 
    "address1": "London", 
    "address2": "1 High Street", 
    "invoiceNumber": "5678", 
    "itemDescription": "Item 3", 
    "itemQuantity": 1 
} 

这是我想达到的目标：

[ 
    { 
     "clientId": "FOO", 
     "name": "John Doe", 
     "address1": "London", 
     "address2": "1 High Street", 
     "deliveries": [ 
      { 
       "invoiceNumber": "1234", 
       "itemQuantity": 1, 
       "itemDescription": "Item 1" 
      }, 
      { 
       "invoiceNumber": "5678", 
       "itemDescription": "Item3", 
       "itemQuantity": 1 
      } 
     ] 
    }, 
    { 
     "clientId": "BAR", 
     "name": "JohnDoe", 
     "address1": "London", 
     "address2": "12 Oxford Street", 
     "deliveries": [ 
      { 
       "invoiceNumber": "0987", 
       "itemDescription": "Item2", 
       "itemQuantity": 1 
      } 
     ] 
    } 
] 

这里是我到目前为止的代码，这不会产生什么，我会希望它会：

 var groups = _.groupBy(rows, function(value) { 
      return value.name + '#' + value.address2; 
     }); 

     var data = _.map(groups, function(group) { 
      return { 
       clientId: group[0].clientId, 
       name: group[0].name, 
       address1: group[0].address1, 
       address2: group[0].address2, 
       deliveries: [{ 
        invoiceNumber: _.map(group,'invoiceNumber'), 
        itemDescription: _.map(group,'itemDescription'), 
        itemQuantity: _.map(group,'itemQuantity'), 
       }] 
      } 
     }); 

而且它产生以下输出：

[ { clientId: 'FOO', 
    name: 'John Doe', 
    address1: 'London', 
    address2: '1 High Street', 
    deliveries: [ [Object] ] } ] 

我不知道如何在lodash _.map函数内创建一个“交付”对象的数组。请帮忙！ :)

Answer 1

使用一个映射，从一组挑选出你想要的属性：

... deliveries: _.map(group, item => _.pick(item, ['invoiceNumber', 'itemDescription', 'itemQuantity' ])) ...

Answer 2

你是为期不远了！

按照Gruff的建议，通过使用ES6语法并将_.pick()合并到您的代码中，让它更简洁一点。

如果你真的喜欢单人泳池，那也是可能的！ Lodash可以很容易地链/嵌套函数要做到这一点，虽然你可能会损害一些可读性：

// Data: 
 
const rows = [{ 
 
    "clientId": "FOO", 
 
    "name": "John Doe", 
 
    "address1": "London", 
 
    "address2": "1 High Street", 
 
    "invoiceNumber": "1234", 
 
    "itemDescription": "Item 1", 
 
    "itemQuantity": 1 
 
}, 
 
{ 
 
    "clientId": "BAR", 
 
    "name": "John Doe", 
 
    "address1": "London", 
 
    "address2": "1 Oxford Street", 
 
    "invoiceNumber": "0987", 
 
    "itemDescription": "Item 2", 
 
    "itemQuantity": 1 
 
}, 
 
{ 
 
    "clientId": "FOO", 
 
    "name": "John Doe", 
 
    "address1": "London", 
 
    "address2": "1 High Street", 
 
    "invoiceNumber": "5678", 
 
    "itemDescription": "Item 3", 
 
    "itemQuantity": 1 
 
}]; 
 

 
// Result: 
 
const groups = _.groupBy(rows, item => item.clientId); 
 
const result = _.map(groups, group => { 
 
    const {clientId, name, address1, address2} = group[0]; 
 
    const deliveries = _.map(group, item => _.pick(item, ['invoiceNumber', 'itemDescription', 'itemQuantity'])); 
 
    return {clientId, name, address1, address2, deliveries}; 
 
}); 
 
console.log('multi-liner result: ', result); 
 

 
// One-line version: 
 
const oneLiner = _.map(_.groupBy(rows, item => item.clientId), group => _.merge(_.pick(group[0], ['clientId', 'name', 'address1', 'address2']), {deliveries: _.map(group, item => _.pick(item, ['invoiceNumber', 'itemDescription', 'itemQuantity']))})); 
 
console.log('one-liner result: ', oneLiner);

<script src="https://cdn.jsdelivr.net/lodash/4.17.1/lodash.min.js"></script>

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希望帮助！如果您想使用的功能Lodash更多信息，下面是他们的官方文档：

• _.groupBy()
• _.map()
• ​​