如何從節點js中的查詢回應中提取json欄位？
我有一個疑問：-
const Allposts = await Post.aggregate([pipeline])
所有帖子：-
{
_id: 1,
type: 'A',
source: 'B',
status: 'C',
totalCount: 7,
createdAt: 2022-04-13T17:12:28.097Z,
updatedAt: 2022-04-13T17:12:28.097Z,
__v: 0
},
{
_id: 2,
type: 'A',
source: 'B',
status: 'C',
totalCount: 7,
createdAt: 2022-04-13T17:12:28.097Z,
updatedAt: 2022-04-13T17:12:28.097Z,
__v: 0
},
{
_id: 3,
type: 'A',
source: 'B',
status: 'C',
totalCount: 7,
createdAt: 2022-04-13T17:12:28.097Z,
updatedAt: 2022-04-13T17:12:28.097Z,
__v: 0
}, and so on
我想提取totalCount欄位并存盤它的值怎么做？
uj5u.com熱心網友回復：
假設totalCount所有物件的值都相同，您可以使用第一個索引提取第一個值
let tc = Allposts[0].totalCount;
顯示代碼片段
let data = [{
_id: 1,
type: 'A',
source: 'B',
status: 'C',
totalCount: 7,
createdAt: '2022 - 04 - 13 T17: 12: 28.097 Z',
updatedAt: '2022 - 04 - 13 T17: 12: 28.097 Z',
__v: 0
},
{
_id: 2,
type: 'A',
source: 'B',
status: 'C',
totalCount: 7,
createdAt: '2022 - 04 - 13 T17: 12: 28.097 Z',
updatedAt: '2022 - 04 - 13 T17: 12: 28.097 Z',
__v: 0
},
{
_id: 3,
type: 'A',
source: 'B',
status: 'C',
totalCount: 7,
createdAt: '2022 - 04 - 13 T17: 12: 28.097 Z',
updatedAt: '2022 - 04 - 13 T17: 12: 28.097 Z',
__v: 0
}
]
let tc = data[0].totalCount;
console.log(tc);uj5u.com熱心網友回復：
如果您僅從totalCount查詢回應中獲取欄位，則可以在查詢中添加 .project() 如下
const Allposts = await Post.aggregate().project("totalCount -_id");
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標籤：javascript 节点.js mongodb 表示 mongodb查询