How can get two collection documents and calculate points using express.js? - node.js

Question

exports.show = = function(req, res) {
var userdata = [{
"productcode": "9563456789",
"cost": "1000"
}, {
"productcode": "8756348947",
"cost": "5600"
}]
var parameterObject = [];
Parameter.find().exec(function(err, Parameters) {
if (err) {
return handleError(res, err);
}
// i want to push Parameters[0].value to parameterObject
parameterObject.push({
pointvalue: Parameters[0].value
});
});
for (var i = 0; i < userdata.length; i++) {
Product.find({
'productcode': userdata[i].productcode
}).exec(function(err, Products) {
if (err) {
return handleError(res, err);
}
var point = 0;
if (!Products) {
point = 0;
} else if (Products[0].product.point > 0) {
point = Products[0].product.point;
}
if (point > 0) {
// here i am not getting userdata[i].cost
//parameterObject.pointvalue value also not getting
totalprice = userdata[i].cost / parameterObject.pointvalue * point;
}
});
}
};
Here i have written function for calculating totalprice. i have mentioned userdata(this is my req.body).
Expectation :
i need to store Parameters objects in some variable to access where ever i want.
i want to pass userdata object in Product.find() function
how can i calculate this
totalprice= userdata[i].cost/parameterObject.pointvalue) * point);

Answer 1

exports.show = = function(req, res) {
var userdata = [{
"productcode": "9563456789",
"cost": "1000"
}, {
"productcode": "8756348947",
"cost": "5600"
}]
var parameterObject = [];
Parameter.find().exec(function(err, Parameters) {
if (err) {
return handleError(res, err);
}
// i want to push Parameters[0].value to parameterObject
parameterObject.push({
pointvalue: Parameters[0].value
});
return FindProducts(parameterObject, function(data) {
console.log(data);
});
});
function FindProducts(parameterObject, callback) {
for (var i = 0; i < userdata.length; i++) {
var totalprice = 0;
findProduct(i, parameterObject, function(i, price) {
totalprice += price;
if (i <= userdata.length) {
return callback({
"userid": "myuserid",
"total": totalprice
});
}
});
}
}
function findProduct(i, parameterObject, callback) {
Product.find({
'productcode': userdata[i].productcode
}).exec(function(err, Products) {
if (err) {
return handleError(res, err);
}
var point = 0;
if (!Products) {
point = 0;
} else if (Products[0].product.point > 0) {
point = Products[0].product.point;
}
if (point > 0) {
// here you can now get the value of userdata[i].cost
// here you can now get the value of parameterObject
totalprice = userdata[i].cost / parameterObject[0].pointvalue * point;
return callback(i, totalprice);
}
});
}
};

Answer 2

You can use promises when you want to use the result of two functions and later use it for further computation.
In your case, you can execute the two asynchronous functions in parallel. It can look like this.
Promise.all([
asyncFunc1(),
asyncFunc2(),
])
.then(function(result){
// result is an array and has the response of the functions which is
// result[0] and result[1]
···
// you can manipulate the result of the functions here
})
.catch(function(err){
// Receives rejection/error among the Promises
···
});
Here asyncFunc1() will be your first find function
asyncFunc2() will be your second find function.
The result[0] and result[1] will be the results of the functions respectively.
Later you can use the result to do further computations.
Hope this helps.