Hvis du bruger node.js, skal du bruge https://github.com/caolan/async
når du skal hente data fra flere samlinger, skal du sammenkæde dine forespørgsler flere gange.
Det vil gøre din kode kompleks og svær at læse og ingen modularitet. Brug async til at skabe modularitet ved hjælp af mongodb og node.js
Eksempelkode fra mit projekt :
var async = require('async');
var createGlobalGroup = function(socket, data) {
async.waterfall(
[
/**
* this function is required to pass data recieved from client
* @param {Function} callback To pass data recieved from client
*/
function(callback) {
callback(null, socket, data);
},
/**
* Step 1: Verify User
*/
verifyUser,
/**
* Step 2: Check User Access Rights And Roles
*/
checkUserAccessRightsAndRoles,
/**
* Step 3: Create Project
*/
createNewGlobalGroup], function(err, result) {
/**
* function to be called when all functions in async array has been called
*/
console.log('project created ....')
});
}
verifyUser = function(socket, data, callback) {
//do your query
/**
* call next function in series
* provide sufficient input to next function
*/
callback(null, socket, data, {
"isValidUser": true,
});
}
checkUserAccessRightsAndRoles = function(socket, data, asyncObj, callback) {
//do your query
if(condition) {
callback(null, socket, data, {
roles: result,
"isValidUser": asyncObj.isValidUser,
"userId": asyncObj.userId,
});
} else {
//no call back
}
}
var createNewGlobalGroup = function(socket, data, asyncObj, callback) {
//wanna stop then no callback
}