我正在用Node.js和mongoose写一个web应用程序。如何对我从.find()调用得到的结果进行分页?我想要一个功能可比的“限制50,100”在SQL。


当前回答

const ITEMS_PER_PAGE = 2;

exports.getProducts = (req, res, next) => {
  // + will turn the string to a number
  const page = +req.query.page || 1;
  let totalItems;
  //Product model
  Product.find()
    .countDocuments()
    .then((numProducts) => {
      totalItems = numProducts;
      return Product.find()
         //If query param is 3, since ITEMS_PER_PAGE = 2, we skip 2*2 items   
         // we show only 5th and 6th item
        .skip((page - 1) * ITEMS_PER_PAGE)
        .limit(ITEMS_PER_PAGE);
    })
    .then((products) => {
      res.render("shop/products", {
        // maybe sending the products object to templating engine
      });
    })
    .catch((err) => {
      const error = new Error(err);
      error.httpStatusCode = 500;
      // if you are set express error handler, use this
      // when we call next() with an argument passed in, we let express know, we skip all other middlewares, we move to error handling middleware

      return next(error);
    });
};

其他回答

你可以使用一个叫Mongoose Paginate的小包,让它更容易。

$ npm install mongoose-paginate

在你的路由或控制器后,只需添加:

/**
 * querying for `all` {} items in `MyModel`
 * paginating by second page, 10 items per page (10 results, page 2)
 **/

MyModel.paginate({}, 2, 10, function(error, pageCount, paginatedResults) {
  if (error) {
    console.error(error);
  } else {
    console.log('Pages:', pageCount);
    console.log(paginatedResults);
  }
}

下面的代码是为我工作良好。 你也可以在countDocs查询中添加查找过滤器和user same来获得准确的结果。

export const yourController = async (req, res) => {
  const { body } = req;

  var perPage = body.limit,
  var page = Math.max(0, body.page);

  yourModel
    .find() // You Can Add Your Filters inside
    .limit(perPage)
    .skip(perPage * (page - 1))
    .exec(function (err, dbRes) {
      yourModel.count().exec(function (err, count) { // You Can Add Your Filters inside
        res.send(
          JSON.stringify({
            Articles: dbRes,
            page: page,
            pages: count / perPage,
          })
        );
      });
    });
};

最简单的分页插件。

https://www.npmjs.com/package/mongoose-paginate-v2

添加插件到一个模式,然后使用模型paginate方法:

var mongoose         = require('mongoose');
var mongoosePaginate = require('mongoose-paginate-v2');

var mySchema = new mongoose.Schema({ 
    /* your schema definition */ 
});

mySchema.plugin(mongoosePaginate);

var myModel = mongoose.model('SampleModel',  mySchema); 

myModel.paginate().then({}) // Usage
const page = req.query.page * 1 || 1;
const limit = req.query.limit * 1 || 1000;
const skip = (page - 1) * limit;

query = query.skip(skip).limit(limit);

简单而强大的分页解决方案

async getNextDocs(no_of_docs_required: number = 5, last_doc_id?: string) {
    let docs

    if (!last_doc_id) {
        // get first 5 docs
        docs = await MySchema.find().sort({ _id: -1 }).limit(no_of_docs_required)
    }
    else {
        // get next 5 docs according to that last document id
        docs = await MySchema.find({_id: {$lt: last_doc_id}})
                                    .sort({ _id: -1 }).limit(no_of_docs_required)
    }
    return docs
}

Last_doc_id:您获得的最后一个文档id

No_of_docs_required:你想要获取的文档数量,例如5、10、50等。

如果你不提供last_doc_id给方法,你会得到5个最新的文档 如果你提供了last_doc_id,那么你会得到下一个,即5个文档。