nodecaf v0.13.3

Nodecaf

Docs for version v0.7.x.

Nodecaf is an Express framework for developing REST APIs in a quick and convenient manner. Using Nodecaf you'll get:

• Useful handler arguments.
• Built-in settings file support with layering and live reload.
• Out-of-the-box logging through GoLog.
• Seamless support for async functions as route handlers.
• Uncaught exceptions in routes always produce proper REST responses.
• Built-in assertions for most common REST scenarios.
• Function to expose global objects to all routes (eg.: database connections).
• Shortcut for permissive CORS on all routes.
• HTTPS capability.
• Functions to describe your API making your code the main source of truth.
• Functions to filter request bodies by mime-type.
• Helpful command line interface.

If you are unfamiliar with Express, checkout their routing docs so that you can better grasp Nodecaf features and whatnot.

Get Started

1. Install the cli utilities: npm i -P -g nodecaf-cli.
2. Create or just go to your node project directory (you must have a package.json).
3. Add to your project with: npm i -P nodecaf.
4. Create a skelleton project with: nodecaf init.
5. Add your globals in lib/main.js

const { AppServer } = require('nodecaf');
const api = require('./api');

module.exports = function init(){
    let app = new AppServer();

    // Expose things to all routes putting them in the 'shared' object.
    let shared = {};
    app.expose(shared);

    // You can intercept all error that escape the route handlers.
    app.onRuoteError = function(input, err, send){
        // Any error that is not handled here will just become a harmless 500.
    };

    // Perform your server initialization logic.
    app.beforeStart = async function(){

    };

    // Perform your server finalization logic.
    app.afterStop = async function(){

    };

    // Load your routes and API definitions.
    app.api(api);

    // Don't forget to return your app.
    return app;
}

6. Add your routes in lib/api.js

module.exports = function({ post, get, del, head, patch, put }){

    // Use express routes and a list of functions (async or regular no matter).
    get('/foo/:f/bar/:b', Foo.read, Bar.read);
    post('/foo/:f/bar', Foo.read, Bar.write);
    // ...
};

Reporting Bugs

If you have found any problems with this module, please:

1. Open an issue.
2. Describe what happened and how.
3. Also in the issue text, reference the label ~bug.

We will make sure to take a look when time allows us.

Proposing Features

If you wish to get that awesome feature or have some advice for us, please: 1. Open an issue. 2. Describe your ideas. 3. Also in the issue text, reference the label ~proposal.

Contributing

If you have spotted any enhancements to be made and is willing to get your hands dirty about it, fork us and submit your merge request so we can collaborate effectively.

Manual

On top of all the cool features Express offers, check out how to use all the awesome goodies Nodecaf introduces.

Handler Args

In this manual we address as handler args the keys in the object passed as the only argument of any route handler function. The code below shows all handler args exposed by Nodecaf:

function({ req, res, next, query, params, body, flash, conf, log, error, headers }){
    // Do your stuff.
}

Quick reference:

• req, res, next: The good old parameters used regularly in Express.
• query, parameters, body, headers: Shortcuts to the homonymous properties of req. They contain respectively the query string, the URL parameters, and the request body data.
• flash: Is a shortcut to Express req.locals. Keys inserted in this a object are preserved for the lifetime of a request and can be accessed in all handlers of a route chain.
• conf: This object contains the entire application configuration data.
• log: A GoLog logger instance. Use it to log custom events of your application.
• Also all keys of the globally exposed object are available as handler args for all routes.
• error: A function to output REST errors and abort the handler chain execution.

Settings File

Nodecaf allow you to read a configuration file and use it's data in all routes and server configuration.

Use this feature to manage:

• external services data such as database credentials
• Nodecaf settings such as SSL and logging
• Your own server application settings for your users

Suported config formats: TOML, YAML, JSON

Check out how to generate a project with configuration file already plugged in

To setup a config file for an existing project, open the binary for your server in bin/proj-name.js. Then add a confPath key to the run parameter object whose value must be a string path pointing to your conf file.

The config data can be passed as an object to the app constructor in lib/main.js:

module.exports = function init(){
    let conf = { key: 'value' };
    let app = new AppServer(conf);
}

You can use the config data through it's handler arg in all route handlers as follows:

post('/foo', function({ conf }){
    console.log(conf.key); //=> 'value'
});

Layered Configs

You can also use the app.setup to add a given configuration file or object on top of the current one as follows:

app.setup('/path/to/settings.toml');

app.setup('/path/to/settings.yaml');

app.setup({ key: 'value' });

app.setup({ key: 'new-value', foo: 'bar' });

Layering is useful, for example, to keep a default settings file in your server source code to be overwritten by your user's.

Live Reload

When in debug mode (app.setup({ debug: true })) changes to loaded config files will trigger aspplication reloads, so you don't have to manually restart the whole node process.

Logging

To setup Nodecaf logger you must add a log key to the application server config object like this:

conf.log = { file: 'path/to/conf/file.log' }; // Use this for a file
conf.log = { stream: process.stdout }; // Use this for a write stream
let app = new AppServer(conf);

You can also setup a log file in your settings file to be automatically transferred to the conf argument of init.

[log]
file = "path/to/conf/file.log"

In your route handlers, use the log handler arg as a GoLog instance:

function({ log }){
    log.info('hi');
    log.warn({lang: 'fr'}, 'au revoir');
}

Nodecaf will automatically log some useful server events as described in the table below:

Async Handlers

Nodecaf brings the useful feature of accepting async functions as route handlers with zero configuration. All rejections/error within your async handler will be gracefully handled by the same routine the deals with regular functions. You will be able to avoid callback hell without creating bogus adapters for your promises.

get('/my/thing',
    function({ res, next }){
        res.send('My regular function works!');
        next();
    },
    async function({ res }){
        await myAsyncThing();
        res.end('My async function works too!');s
    }
);

Error Handling

In Nodecaf, any uncaught synchronous error happening inside route handler will be automatically converted into a harmless RESTful 500.

post('/my/thing', function(){
    throw new Error('Should respond with a 500');
});

To support the callback error pattern, use the error handler arg.

const fs = require('fs');

post('/my/thing', function({ error, res }){
    fs.readFile('./my/file', 'utf8', function(err, contents){
        if(err)
            return error(err, 'Optional message to replace the original');
        res.end(contents);
    });
});

To use other HTTP status codes you can send a string in the first parameter of error. The supported error names are the following:

post('/my/thing', function({ error }){
    try{
        doThing();
    }
    catch(e){
        error('NotFound', 'Optional message for the JSON response');
    }
});

You can always deal with uncaught exceptions in all routes through a default global error handler. In your lib/main.js add an onRuoteError function property to the app.

app.onRuoteError = function(input, err, send){

    if(err instanceof MyDBError)
        send('ServerFalut', 'Sorry! Database is sleeping.');
    else if(err instanceof ValidationError)
        send('InvalidContent', err.data);
}

• The send function will instruct Nodecaf to output the given error.
• The input arg contain all handler args for the request.
• If you do nothing for a specific type of Error the normal 500 behavior will take place.

REST Assertions

Nodecaf provides you with an assertion module containing functions to generate the most common REST outputs based on some condition. Check an example to trigger a 404 in case a database record doesn't exist.

let { exist } = require('nodecaf').assertions;

get('/my/thing/:id', function({ params, db }){
    let thing = await db.getById(params.id);
    exist(thing, 'thing not found');

    doStuff();
});

If the record is not found, the exist call will stop the route execution right away and generate a RESTful NotFound error.

Along with exist, the following assertions with similar behavior are provided:

To use it with callback style functions, pass the error handler arg as the third parameter.

let { exist } = require('nodecaf').assertions;

post('/my/file/:id', function({ error, res, params }){
    fs.readFile('./my/file/' + params.id, 'utf8', function(err, contents){
        exist(!err, 'File not found', error);
        res.end(contents);
    });
});

Expose Globals

Nodecaf makes it simple to share global objects (eg.: database connections, instanced libraries) across all route handlers. In your lib/main.js you can expose an object of which all keys will become handler args.

app.expose({
    db: myDbConnection,
    libX: new LibXInstance()
});

Then in all routes you can:

get('/my/thing', function({ db, libX }){
    // use your global stuff
});

CORS

Nodecaf provides a setting to enable permissive CORS on all routes. Defaults to disabled. In your conf file:

cors = true

HTTPS

In production it's generally desirable to have an HTTPS setup for both client to API and API to API communications. You can enable SSL for your server by adding a ssl key to your config, containing both the path for your key and cert.

[ssl]
key = "/path/to/key.pem"
cert = "/path/to/cert.pem"

When SSL is enabled the default server port becomes 443.

Filter Requests by Mime-type

Nodecaf allow you to reject request bodies whose mime-type is not in a defined white-list. Denied requests will receive a 400 response with the apporpriate message.

Define a filter for the entire app on your api.js:

module.exports = function({ }){

    this.accept(['json', 'text/html']);

}

Override the global accept per route on your api.js:

const { accept } = require('nodecaf');

module.exports = function({ post, put }){

    // Define global accept rules
    this.accept(['json', 'text/html']);

    // Obtain accepts settings
    let json = accept('json');
    let img = accept([ 'png', 'jpg', 'svg', 'image/*' ]);

    // Prepend accept definition in each route chain
    post('/my/json/thing', json, myJSONHandler);
    post('/my/img/thing', img, myImageHandler);
}

API Description

Nodecaf allows you to descibe your api and it's functionality, effectively turning your code in the single source of truth. The described API can later be used to generate an Open API compatible document.

In lib/api.js describe your API as whole through the info parameter:

module.exports = function({ get, info }){

    info({
        description: 'My awesome API that foos the bars and bazes the bahs'
    });

    get('/my/thing/:id', function(){
        // ...
    });
}

The info funciton expects an object argument on the OpenAPI Info Object format. If not defined the title and version keys will default to your server's.

Describe your API endpoints by chaining a desc method to each route definition.

module.exports = function({ get }){

    get('/my/thing/:id', function(){
        // ...
    }).desc('Retrieves a thing from the database\n' +
        `Searches the database for the thing with the given :id. Returns a
        NotFound error in case no thing is found.`);
}

The desc method takes a single string argument and uses it's first line (before \n) to set the Operation object's summary property and the rest of the text to set the description (CommonMark).

Other Settings