在nodejs和mongodb的服务器端分页

Question

请帮助我在node js和mongo db中进行服务器端分页

function getServiceQualityAnex(req, res, next) {
if (req.query.code != null) {
ServiceQualityAnex.find({ location: req.query.code }).sort({ _id: -1 }).select('-hash')
.then(serviceQualityAnexC => res.json(serviceQualityAnexC))
.catch(err => {
res.sendStatus(404);
next(err)
});
} else {
ServiceQualityAnex.find({}).sort({ _id: -1 }).select('-hash')
.then(serviceQualityAnexC => res.json(serviceQualityAnexC))
.catch(err => {
res.sendStatus(404);
next(err)
});
}
}

Answer 1

我想在服务器端做一个服务器端分页，我的前端api是http://localhost:3000/getServiceQualityAnexJoin/上面提到的函数是结合2个表返回。我的数据非常大，我想添加一个服务器端分页

Answer 2

你没有在你的问题中指定所有的要求，但我所看到的是你想在mongodb的nodejs服务器端做分页下面是你需要做的:

const getServiceQualityAnex = async (request, response) => {
try {
const id = request.params.id;
let { page } = request.query; //this indicates the page you are requesting for in pagination
if (!page)
page = 1; //by default it is one
const result = await ServiceQualityAnex.aggregate([
{
$match: {
"_id": mongoose.Types.ObjectId(id)
}
},
{
$project: {
"_id": 1,
.
.
.
// all the fields you want to get
}
},
{
$facet: { //facet is the aggregation pipeline in mongodb through which you can achieve pagination 
metadata: [{ $count: 'total' }],
data: [
{
$skip: (Number(page) - 1) * Number(20)
},
{
$limit: 20 //20 records limit per page
},
]
}
}
]);
console.log("result :", result[0].data);
return response
.status(200)
.json(
{
result: result[0].data,
meta: {
current_page: page,
total_pages: Math.ceil(
(Number(result[0].metadata.length === 0 ? 0 : result[0].metadata[0].total))
/ (Number(20))),
total_count: result[0].metadata.length === 0 ? 0 : result[0].metadata[0].total,
}
}
);
} catch (error) {
console.log(error);
response.status(500).json({
error: "Something went wrong",
});
}
}

如果你对聚合一无所知，那么你一定要访问这个网站:MongoDB聚合框架

Answer 3

let page = Number(req.query.page);
page = page ? page : 0;
let limit = parseInt(req.query.limit);
const result = {};
let startIndex = page * limit;
if (startIndex > 0) {
result.previous = {
page: page - 1,
limit: limit,
};
}
let receive = await Model.find()
.sort("-_id")
.skip(startIndex)
.limit(limit)
.exec();