Question

我有点卡在这个问题上。

基本上我想在reqBody.address存在时更新db.address，如果不存在则使用现有值。我目前不得不两次遍历我的db json;首先将变量设置为原始地址，然后在确定是否使用新创建的变量或reqBody.address时再次分配/合并。

我只想穿越一次。

除了显而易见的检查，只有当reqBody.address存在时我才会想知道这是否可以通过从assign中的函数返回值在单个语句中完成。

下面是我的代码到目前为止，我想要消除整个第一个db_address链命令，并让第二个链命令使用类似的东西：

.merge({ address: req_address || address }  })

其中地址跟在||之后是原始值。

const _ = require('lodash')
const moment = require('moment');

let reqBody = {"address_list":[{"address_type":"Home","address":"99 West Street"}]}
let db = {"users":[{"id":1,"name":"Joe","address_list":[{"address_type":"Home","address":"11 High Street","created_date":"2018-01-08","updated_date":""}]}]}

let req_address = reqBody.address_list[0].address;
let db_address  = _.chain(db)
               .get('users').find({id: 1})
               .get('address_list')
               .filter((address) => {return address.address_type === reqBody.address_list[0].address_type})
               .get('[0].address')
               .value()

db_address = _.chain(db)
          .get('users').find({id: 1})
          .get('address_list')
          .filter((address) => {return address.address_type === reqBody.address_list[0].address_type})
          .get('[0]')
          .merge({ address: req_address || db_address },
                 { updated_date: moment().format() }
                )
          .value()

console.log(db_address)

提前致谢

干杯

PS：再次感谢Markus突出合并

Answer 1

如果您只想更新db use .merge({ adress: req_address })中的值，则不需要第一个链，如果值未定义，merge将不会覆盖：

如果目标值存在，则跳过解析为未定义的源属性。

这仍然会更新时间戳，但不确定这是否有问题。

或者，使用update，即您要求的function funning inside assign，也不允许更新时间戳。

带有merge

的版本

const _ = require('lodash')
const moment = require('moment');

let reqBody = {"address_list":[{"address_type":"Home","address":"99 West Street"}]}
let db = {"users":[{"id":1,"name":"Joe","address_list":[{"address_type":"Home","address":"11 High Street","created_date":"2018-01-08","updated_date":""}]}]}

let req_address = reqBody.address_list[0].address;

db_address = _.chain(db)
          .get('users').find({id: 1})
          .get('address_list')
          .filter((address) => {return address.address_type === reqBody.address_list[0].address_type})
          .get('0')
          .merge({ address: req_address },
                 { updated_date: moment().format() }
                )
          .value()

console.log(db_address)

带更新的版本

const _ = require('lodash')
const moment = require('moment');

let reqBody = {"address_list":[{"address_type":"Home","address":"99 West Street"}]}
let db = {"users":[{"id":1,"name":"Joe","address_list":[{"address_type":"Home","address":"11 High Street","created_date":"2018-01-08","updated_date":""}]}]}

let req_address = reqBody.address_list[0].address;

db_address = _.chain(db)
          .get('users').find({id: 1})
          .get('address_list')
          .filter((address) => {return address.address_type === reqBody.address_list[0].address_type})
          .update(
            '0',
            address =>
              req_address ?
                {
                  ...address,
                  address: req_address,
                  updated_date: moment().format()
                } :
                address
          )
          .value()

console.log(db_address)

Answer 2

在玩了一点之后，我只是添加了this，它现在正在工作......太棒了。

          .merge({ address: req_address || this.address },
                 { updated_date: moment().format() }
                )

干杯

lodash：在assign（）里面运行函数

2 个答案: