javascript - 高效地查找以前的帖子(keystoneJS)

Question

我正在寻找以前的帖子。我知道我可以加载所有帖子并从那里检查..但这似乎数据量很大。有没有更简洁的方法来查询上一篇文章？也许有排序？或者也许有一种方法可以限制检索到的数据量.. 就像 slug 一样，这样它的数据量就更少了？

我只是想提出一个简单的请求并找到下一篇文章。

这是我目前的解决方案

var keystone = require('keystone');

exports = module.exports = function(req, res) {
    var view = new keystone.View(req, res),
        locals = res.locals;

    // Set locals
    locals.section = 'news';
    locals.filters = {
        post: req.params.post
    }
    locals.data = {
        previousPost: []
    }

    // Load the current post
    view.on('init', function(next) {

        var q = keystone.list('Post').model.findOne({
            state: 'published',
            slug: locals.filters.post
        }).populate('author categories');

        q.exec(function(err, result) {
            locals.data.post = result;
            next(err);
        });

    });

    // Load previous post
    view.on('init', function(next) {
        var q = keystone.list('Post').model.find().where('state', 'published').sort('-publishedDate');
        q.exec(function(err, results) {
            allPosts = results;
            for (var i = 0; i < allPosts.length; i++) {
                if (allPosts[i]["slug"] === locals.filters.post) {
                    locals.data.previousPost = allPosts[i+1];
                    next(err);
                }
            }
        });
    });

    // Render the view
    view.render('post');    
}

Answer 1

对应的mongo查询为:
db.posts.find({state: "published", 发布日期: {$lt: currentpost.publishedDate}}).sort({publishedDate: -1}).limit(1)


我认为对应的 keystone/mongoose 查询是:
var q = keystone.list('Post').model.find({state: "published", publishedDate: {$lt: currentpost.publishedDate}}).sort('-publishedDate').limit(1);


如果您只想选择，例如，帖子的标题，那么您可以添加一个选择查询过滤器:
var q = keystone.list('Post').model.find({state: "published", publishedDate: {$lt: currentpost.publishedDate}}).sort('-publishedDate').select('title') .limit(1);


等效的 mongo 查询类似于:
db.posts.find({state: "published", publishedDate: {$lt: currentpost.publishedDate}},{title: 1}).sort({publishedDate: -1}).limit(1)


还有其他不同的方式来编写这些查询:-)