Mongoose Optimized Paginate (MOP)

Optimized pagination using indexes (no cursor.skip) with fallback. Used with Mongoose + Express, or Mongoose + Koa.

Getting Started

$ npm install mongoose-opt-paginate

The MOP plugin returns an object containing a property for accessing the api (paginate function) and a property for accessing the mongoose plugin.

The first step is to include the plugin in your mongoose instance e.g.

var mongoose = require('mongoose'),
    mongoosePlugin = require('mongoose-opt-paginate').plugin;
mongoose.plugin(mongoosePlugin);

Now you can start paginating!

Express Examples

var mongoose = require('mongoose'),
    // returns a function(model, [config])
    paginate = require('mongoose-opt-paginate').api;

// assuming a course model exists
var model = mongoose.model('Course');

// returns a function(req, res, next, search, options, cb)
paginate = paginate(model);

app.get('/courses', function(req, res, next) {
    // no callback will assume end of route (res.json called with results)
    paginate(req, res, next, {}, {});
    // with callback
    paginate(req, res, next, {}, {}, function(results) {
        /* results = {
            "page": 1,
            "hasMore": true,
            "links": {
                "first": "/courses?page=1&currentPage=1&pageSize=10",
                "next": "/courses?page=2&currentPage=1&pageSize=10&after=<encoded>",
                "last": "/courses?page=2&currentPage=1&pageSize=10&last=true"
            },
            "pageCount": 10,
            "total": 14,
            "before": "<encoded>",
            "after": "<encoded>",
            "data": [{<courses>}]
        } */

        // do something with results

        res.json(results);
    });
});

app.get('/other-courses', function(req, res, next) {
    var options = {};
    model.paginate(
        req.query.search,
        req.query.currentPage,
        req.query.page,
        req.query.pageSize,
        options
    )
    .then(function(pagingData) {
        /* pagingData = {
            newCurrentPage: 1,
            "before": "<encoded>",
            "after": "<encoded>",
            "pageCount": 10,
            "numPages": 10,
            "total": 100,
            "items": [{<courses}]
        }; */

        res.json(pagingData);
    });
});

Koa Examples

var mongoose = require('mongoose'),
    // returns a function(model, [config])
    paginate = require('mongoose-opt-paginate').koa;

// assuming a course model exists
var model = mongoose.model('Course');

// returns a function(ctx, search, options, cb)
paginate = paginate(model);

router.get('/courses', function* () {
    var ctx = this;
    // no callback will assume end of route (ctx.body called with results)
    paginate(ctx, {}, {});
    // with callback
    paginate(ctx, {}, {}, function(results) {
        /* results = {
            "page": 1,
            "hasMore": true,
            "links": {
                "first": "/courses?page=1&currentPage=1&pageSize=10",
                "next": "/courses?page=2&currentPage=1&pageSize=10&after=<encoded>",
                "last": "/courses?page=2&currentPage=1&pageSize=10&last=true"
            },
            "pageCount": 10,
            "total": 14,
            "before": "<encoded>",
            "after": "<encoded>",
            "data": [{<courses>}]
        } */

        // do something with results

        ctx.body = results;
    });
});

app.get('/other-courses', function* () {
    var ctx = this;
    var options = {};
    model.paginate(
        req.query.search,
        req.query.currentPage,
        req.query.page,
        req.query.pageSize,
        options
    )
    .then(function(pagingData) {
        /* pagingData = {
            newCurrentPage: 1,
            "before": "<encoded>",
            "after": "<encoded>",
            "pageCount": 10,
            "numPages": 10,
            "total": 100,
            "items": [{<courses}]
        }; */

        ctx.body = pagingData;
    });
});

Things to Note

before and after are encoded strings containing the necessary item information of the first and last item of the returned results for optimized pagination. If sorting, make sure a compound index (collection-level) exists for the sort field(s) and _id field in proper order

e.g. So if you're sorting by name, date, and _id (_id is always there by default and follows the same order as the first/primary sort key: name, in this case) and you want optimized pagination, the compound indexes {name: 1, date: 1, _id: 1} (for optimization when primary sort key in ascending) and {name: -1, date: 1, _id: -1} (for optimization when primary sort key in descending) should exist on the collection-level (not schema-level). Opposite compound indexes don't need to be created i.e. {name: -1, date: -1, _id: -1} and {name: 1, date: -1, _id: 1} wouldn't need to be added if the above indexes already exist.

If sorting (with more than by _id since it's always included) and a matching compound index is not found, pagination will fall back to a non-optimized state. If it's just by _id, no worries, there's a default index for _id that always exists.

Contributing

Looking to contribute? Awesome! Make sure you've got EditorConfig installed to maintain the existing code style. Send your PRs to the dev branch. Before opening a PR, test and lint your code using npm run ci.

Todo's

• Write unit and integration tests
• Documentation

Release History

1.0.0

• Added support for koa pagination
• The mongoose plugin now uses promises rather than callbacks

0.3.0

• Added some unit tests to mongoosePaginateSpec.js.
• Can now provide both options.before and options.after. The library handles the logic of which to use.

0.2.0

• expressPaginate.js tests completed. Started writing mongoosePaginate.js tests.
• FIX: sortBy params including non-alphabetical characters being replaced with empty space during splitting of param string.

0.1.0

• Testing stack has been finalized. Linting has been included.

0.0.11

• Returning results as opposed to ending route by calling res.json

License

MIT