Express Utilities

Most commonly used middlewares and classes for building a web app.

Middlewares

branchRoute(reducer, handlersMap[, options])

For branching a route depends on specific property from request object. This will be much useful in roles based request handling. And many other scenarios.

reducer(req) is a function will return a value to determine which handler by the value key from request should be used.

handlersMap is a plain object contains key-handler pairs. Each handler is a standard express middleware function with req, res and next parameters be passed in.

options is an object has 2 optional default handlers to be configured: keyNotFound and handlerNotSet.

app.get('/user', branchRoute(function (req) {
    return req.session.role;
}, {
    user: [
        function (req, res) {
            user.get(req.session.id).then(function (result) {
                res.data(result);
            })
        }
    ],
    admin(req, res) {
        user.getAll(results).then(function (results) {
            res.data(results);
        });
    }
}, {
    keyNotFound(req, res) {
        return res.notfound();
    },

    handlerNotSet(req, res) {
        return res.notfound();
    }
}));

meta

Only add a object named meta to the request object for holding any request based variables.

Recommend to use in global. And will be required by pagination and validation.

response

Add a lot of method based on HTTP status code to do RESTful styled responses:

• data(data): 200
• created(data): 201
• accepted(): 202
• ok(): 204
• done(): 205
• badrequest(data): 400
• unauthorized(): 401
• forbidden(): 403
• notfound(): 404
• mehtodnotallow(): 405
• conflict(): 409
• invalid(fields): 422
• error(errors): 500
• unavailable(): 503

app.get('/book/:id', function (req, res) {
    bookService.get(req.params.id).then(result => {
        res.data(result);
    }).catch(() => {
        res.notfound();
    });
});

pagination(options)

Provide a middleware to parse pagination parameters from query or other part based on request, and a output method named paged() to calculate real page based on data rows and all count.

By default, it use query as source and page/size for input. They could be changed in options.

app.get('/book', pagination({
    from: 'query', // could use `params`/`headers` and so on
    pageKey: 'page',
    sizeKey: 'size'
}), function (req, res) {
    bookService.getAll({ name: req.query.name }, req.meta.paginator).then(({ count, rows }) => {
        res.paged({ count, rows });
    });
});

pagination middleware requires meta to be used before.

validation(schema)

Provide input validation before a request goes into main business logic by using express-validation and Joi.

When invalid input happens, will return a 422 status code with all error fields in body to client.

app.post('/book', validation({
    body: {
        name: joi.string().required(),
        auther: joi.string().required()
    },
    allowUnknownBody: false
}), function (req, res) {
    bookService.create(req.body).then(result => {
        res.created(result);
    })
})

validation middleware requires response to be used before.

ModelService

Wrapped commonly used CRUD methods in Sequelize ORM. All where and options are same in Sequelize could be checked in its docs.

constructor

const bookService = new ModelService({
    name: 'Book' // model name in sequelize model definition
});

async get(id, options)

Get a row by primary key.

async getOne(where = {}, options = {})

Get one row based on where conditions and options.

async getAll(where = {}, options = {})

Get a list based on where conditions and options.

async update(id, data, options = {})

Update a row by primary key.

async remove(id, options = {})

Remove a row by primary key.

async changePriority(item, span, where = {})

For ordering rows by a manual priority key.

MIT Licensed