How to chain http.request() - node.js

Question

I need to use require('http') (I cannot use other libraries), and I am trying to figure out how I would chain multiple http.request() together?
In my example below, I am trying to create a household with 4 people, and each person will have a pet associated to them. I have 3 routes that will createFamily, createPerson, and createPet. I also have the method createHousehold() that will take the ID's from the response of each route, and pass it down the chain (family -> person -> pet). I am not sure how I would be chaining the response of each route, and passing down the ID.
const http = require('http');
createHousehold('Smith', 4); // Creates 'Smith' family with 4 people, and each member has one pet
// Not sure how to chain requests
function createHousehold(surname, numberOfPeople) {
createFamily(surname)
.then(familyId => {
for (let i = 0; i < numberOfPeople; i++) {
createPerson(familyId)
.then(personId => createPet(personId));
}
});
}
function createFamily(surName) {
const data = JSON.stringify({
config: { surName }
});
const options = {
host: 'myProxyHost.com',
port: '8080',
path: '/v1/family',
method: 'POST',
headers: {
'Content-Type': 'application/json',
'Content-Length': data.length,
},
};
const request = http.request(options, response => {
let data = '';
response.on('data', chunk => data += chunk);
return (response.on('end', () => JSON.parse(data).id));
});
request.on('error', error => console.log('ERROR - createFamily(): ', error.message));
request.write(data);
request.end();
return request;
}
function createPerson(familyId) {
const data = JSON.stringify({
config: { familyId }
});
const options = {
host: 'myProxyHost.com',
port: '8080',
path: '/v1/person',
method: 'POST',
headers: {
'Content-Type': 'application/json',
'Content-Length': data.length,
},
};
const request = http.request(options, response => {
let data = '';
response.on('data', chunk => data += chunk);
return (response.on('end', () => JSON.parse(data).id));
});
request.on('error', error => console.log('ERROR - createPerson(): ', error.message));
request.write(data);
request.end();
return request;
}
function createPet(personId) {
const data = JSON.stringify({
config: { personId }
});
const options = {
host: 'myProxyHost.com',
port: '8080',
path: '/v1/pet',
method: 'POST',
headers: {
'Content-Type': 'application/json',
'Content-Length': data.length,
},
};
const request = http.request(options, response => {
let data = '';
response.on('data', chunk => data += chunk);
return (response.on('end', () => JSON.parse(data).id));
});
request.on('error', error => console.log('ERROR - createPet(): ', error.message));
request.write(data);
request.end();
return request;
}

Answer 1

For example with a proxy server, you would pipe one request (readable) into another request (writable).
If you are just doing serial requests, I would just wrap them in a promise, or use the async library.
function createPet(personId) {
return new Promise((resolve,reject) => {
const data = JSON.stringify({
config: { personId }
});
const options = {
host: 'myHost.com',
port: '8080',
path: '/v1/pet',
method: 'POST',
headers: {
'Content-Type': 'application/json',
'Content-Length': data.length,
},
};
const request = http.request(options, response => {
let data = '';
response.on('data', chunk => data += chunk);
response.once('end', () => resolve(data)); // ! resolve promise here
});
request.once('error', err => {
console.log('ERROR - createPet(): ', err.message || err);
reject(err); // ! if promise is not already resolved, then we can reject it here
});
request.write(data);
request.end();
});
}
and use it like so:
createHousehold(id)
.then(createFamily)
.then(createPerson)
.then(createPet);
if you want to do things in parallel, then use Promise.all()..or use the async library.
For seeding a database, I highly recommend async.autoInject, you will quickly see why:
https://caolan.github.io/async/v2/docs.html#autoInject
you can use it like so:
const seedDatabase = () => {
return async.autoInject({ // returns a promise
async createHouseHold(){
return somePromise();
},
async createFamily(createHouseHold){
return somePromise();
},
async createPerson(createFamily){
return somePromise();
},
async createPet(createPerson){
return somePromise();
}
});
}