如何在单个数组中提取所有金额?

Question

[
{
"timestamp": "2018-09-25T12:38:10.436Z",
"_id": "5ba1154d7c0f70472c6cd97d",
"rate": [
{
"_id": "5ba116f6ffcbd8369811653a",
"amount": 5004,
"makerfee": 0.1,
"takerfee": 0.2,
"cc_exchange": "Bitfinex"
},
{
"_id": "5baa0dd1168c0e448469c0b0",
"amount": 100000,
"makerfee": 0.2,
"takerfee": 0.3,
"cc_exchange": "Bitfinex"
},
{
"_id": "5baa1e1c5e3bfc4554e72225",
"amount": 150000,
"makerfee": 0.3,
"takerfee": 0.4,
"cc_exchange": "Bitfinex"
}
],
"cc_exchange": "Bitfinex",
"user": "5ba10e5f7d1a6e0a40b82812",
"__v": 1
},
{
"timestamp": "2018-09-25T12:38:10.443Z",
"_id": "5ba381cef579772bc48f241a",
"rate": [
{
"_id": "5ba381cef579772bc48f241b",
"amount": 5,
"makerfee": 0.1,
"takerfee": 0.2,
"cc_exchange": "Cex"
},
{
"_id": "5baa1d7a9bbfb415a43f7730",
"amount": 10,
"makerfee": 0.2,
"takerfee": 0.3,
"cc_exchange": "Cex"
},
{
"_id": "5baa1df75e3bfc4554e72224",
"amount": 15,
"makerfee": 0.3,
"takerfee": 0.4,
"cc_exchange": "Cex"
}
],
"cc_exchange": "Cex",
"user": "5ba10e5f7d1a6e0a40b82812",
"__v": 0
}]

这是蒙戈文件。我只想提取单个数组中的金额。我在后端使用节点。请告诉我该怎么做。我尝试使用for循环，但无法提取它。请让我知道查询是否可能。提前谢谢。

Answer 1

你可以在节点端使用 Javascript 提取数量.js如下所示：

const document = [ /* your document */ ];
const amounts = [];
document.map(elem => elem.rate)
.map(rateArr => rateArr.forEach(rate => amounts.push(rate.amount)));

这将创建一个如下所示的数组：

[5004, 100000, 150000, 5, 10, 15]