OKATSU : Emphasize Domain

​ OKATSU has been created to focus on domain part rather than technical part of an API. It takes an approach from functional programming and try to bring domain into spot light.

feature function is the core of OKATSU. Through this function you'll be able to express verbosely what your endpoint has to do.

Here an example of implementation with OKATSU framework : https://github.com/wonkledge/okatsu-api-example

Medium article on okatsu https://medium.com/@alexandre.wonkledge.leroy/create-nodejs-api-embrace-your-domain-with-express-mongoose-and-okatsu-c51c30dcb54a

Okatsu has been made to work with Express and Mongoose.

If you have questions, ideas or just want to discuss about it you can reach me out :

​ @wonkledge on twitter

​ @wonkledge on stackOverflow

​

Documentation

feature

​ Resolve every function from right to left.

Be careful

​ Last function must be sendResponse otherwise your API will not respond.

Signature

​ @wonkledge/okatsu/lib/promise/feature -> ...functions -> input -> Promise

Example

const validators = [];
const mapper = [];

//fetchData is a call to a DB

const getAllData = (req, res) => {
  feature(sendResponse(res), mapFields(mapper), query(fetchData), checkParameters(validators))(req)
}

resolved

​ Returns promise resolved with data passed in.

Signature

​ @wonkledge/okatsu/lib/promise/resolved -> data -> Promise.resolve

Example

const sum3 = input => resolved(input + 3)
// output : new Promise((resolve) => resolve(data));

rejected

​ Returns promise rejected with data passed in.

Signature

​ @wonkledge/okatsu/lib/promise/rejected -> data -> Promise.reject

Example

const sum3 = input => rejected(input + 3)
// output : new Promise((resolve, reject) => reject(data));

combine

​ Returns an object with type combine and an array of functions passed in.

Signature

​ @wonkledge/okatsu/lib/operator/combine -> ...functions -> object

Example

const sum3 = input => input + 3;
const times2 = input => input * 2;

const sum3Times2 = combine(times2, sum3);
//output : { type: combine, combinations: [times2, sum3] }

either

​ Returns an object with type either, left part contains function that will be called if previous promise is resolved, right part contains function that will be called if previous promise is rejected.

Signature

​ @wonkledge/okatsu/lib/operator/either -> (left, right) -> object

Example

const sum3 = input => input + 3;
const times2 = input => input * 2;

const times2OrSum3 = either(times2, sum3);
//output : { type: either, left: times2, right: sum3 }

checkParameters

​ checkParameters will raise errors if field provided are missing or predicate failed. Errors are raised into promise reject.

​ checkParameters will return params checked into promise resolve.

Be careful

​ That function must be used inside feature function

Signature

​ @wonkledge/okatsu/lib/validator/checkParameters -> validators -> params -> Promise.resolved || Promise.rejected

Example

const validators = [
    {
        field: 'id',
        predicate: id => id.toString().match(/^[0-9]+$/),
        errorMessage: 'id must be integer'
    }
];

checkParameters(validators) // output : Promise resolve with params or Promise reject with error raised

mapFields

Be careful

​ This function must be used inside feature function.

Signature

​ @wonkledge/okatsu/lib/datamapper/mapFields -> mapping -> data -> Promise.resolved

Example

const mapping = [
    {
        source: 'bestSeller',
        target: 'best_seller'
    },
    {
        source: 'sales',
        target: 'sales',
        transform: (sales) => sales > 100000 ? "Damn it, you're famous" : "Who are you ?"
    }
];

mapFields(mapping); //output : Promise resolve with data mapped

sendResponse

Signature

​ @wonkledge/okatsu/lib/response/sendResponse -> res -> either

Example

// variable res is given by express to respond.
sendResponse(res) // output : { type: either, left: handleResponse, right: handleErrorResponse } 

query

Signature

​ @wonkledge/okatsu/lib/mongooseAdapter/query -> callback -> combine

Example

// Consider Data is a model of mongoose library
const fetchData = (params) => Data.find();
query(fetchData)

httpResponseWrapper

Signature

​ @wonkledge/okatsu/lib/httpCode/httpResponseWrapper -> (httpCode, payload) -> object

Example

httpResponseWrapper(HTTP_CODE_500, 'Something bad happen') // output : { code: 500, payload : 'Something bad happen'}