Develop Reference

API call giving empty array in nodejs

This is 'product.js' file, and when ever I am calling the api '/achaar/products/1', the value of val is giving empty in console. Other api calls like '/achaar/products' is working fine, but on calling with id this is not working.
const express = require('express')
const router = express.Router();
const json_data = require('./test_data');
const cons = require('./constants')
/*
url is : /achaar/products
replace test data with database datas
*/
router.get(cons.URLS.all_product,(req,res) => {
res.json(json_data)
})
router.get(cons.URLS.all_product+'/:id',(req,res) => {
console.log(req.params.id)
var val = json_data.achaar.filter(function (x) { return x.id === req.params.id })
console.log(val)
})
module.exports = router
Here is my test_data.js file
{
"achaar" : [
{
"id" : 0,
"name" : "Ginger Tangi",
"cost" : 2000
},
{
"id" : 1,
"name" : "Mango Khatta",
"cost" : 1200
},
{
"id" : 2,
"name" : "Gaas Dhari",
"cost" : 3000
},
{
"id" : 3,
"name" : "Cream Tangy",
"cost" : 1000
}
]
}

Because you use === and it was check value and type is equal
You should convert req.params.id to number because id of data is number.

How to intersection query Real-time Firebase database?

I'm trying to gain an understanding of query in Firebase. I want to pass userId A & B and find out if they are subscribed to a common chatId, it will either return true or false.
How can query both userId and evaluate results for my desired output?
export const checkForExistingChat = (currentUserId, recipient) => {
var IdList = {}
var query = database
.ref(`Chats/${currentUserId}`)
.orderByChild("subscribedToChat")
.once("value", function (dataSnapshot) {
dataSnapshot.forEach(function (childSnapshot) {
const childData = childSnapshot.val();
console.log("childData : ", childData);
});
});
};
Export JSON of Chat
"Chats" : {
"61vtPjp8YVVSzpvexwXMgEHghYf1" : {
"subscribedToChat" : {
"1a555cbf-30b7-4c8f-9986-4252a7620c45" : "1a555cbf-30b7-4c8f-9986-4252a7620c45",
"2d718ea7-eafa-48db-af14-f165f07b3b08" : "2d718ea7-eafa-48db-af14-f165f07b3b08",
"2e4fd8bb-4afb-4229-83ec-5a427fe2731d" : "2e4fd8bb-4afb-4229-83ec-5a427fe2731d",
"35c537ef-57dd-48c5-9350-5d1fe2e9d118" : "35c537ef-57dd-48c5-9350-5d1fe2e9d118",
"3a816ac1-6e97-4d66-ae19-77e65f8c2df4" : "3a816ac1-6e97-4d66-ae19-77e65f8c2df4",
}
},
"qqpBNbEa8ZSiCEUlseFeGeiRqzh2" : {
"subscribedToChat" : {
"1a555cbf-30b7-4c8f-9986-4252a7620c45" : "1a555cbf-30b7-4c8f-9986-4252a7620c45",
"35c537ef-57dd-48c5-9350-5d1fe2e9d118" : "35c537ef-57dd-48c5-9350-5d1fe2e9d118"
}
}
}

Since you already know how to load data from Firebase, this is essentially a non-Firebase problem: finding the overlapping keys in two lists of keys.
A quick code snippet:
var json = {
"Chats" : {
"61vtPjp8YVVSzpvexwXMgEHghYf1" : {
"subscribedToChat" : {
"1a555cbf-30b7-4c8f-9986-4252a7620c45" : "1a555cbf-30b7-4c8f-9986-4252a7620c45",
"2d718ea7-eafa-48db-af14-f165f07b3b08" : "2d718ea7-eafa-48db-af14-f165f07b3b08",
"2e4fd8bb-4afb-4229-83ec-5a427fe2731d" : "2e4fd8bb-4afb-4229-83ec-5a427fe2731d",
"35c537ef-57dd-48c5-9350-5d1fe2e9d118" : "35c537ef-57dd-48c5-9350-5d1fe2e9d118",
"3a816ac1-6e97-4d66-ae19-77e65f8c2df4" : "3a816ac1-6e97-4d66-ae19-77e65f8c2df4",
}
},
"qqpBNbEa8ZSiCEUlseFeGeiRqzh2" : {
"subscribedToChat" : {
"1a555cbf-30b7-4c8f-9986-4252a7620c45" : "1a555cbf-30b7-4c8f-9986-4252a7620c45",
"35c537ef-57dd-48c5-9350-5d1fe2e9d118" : "35c537ef-57dd-48c5-9350-5d1fe2e9d118"
}
}
}
};
var keys1 = Object.keys(json.Chats["61vtPjp8YVVSzpvexwXMgEHghYf1"].subscribedToChat);
var keys2 = Object.keys(json.Chats["qqpBNbEa8ZSiCEUlseFeGeiRqzh2"].subscribedToChat);
console.log(keys1, keys2);
var commonKeys = keys1.filter(function(key) {
return keys2.indexOf(key) >= 0;
});
console.log(commonKeys);
This is an O(n^2) algorithm, but I doubt that'll be a concern on the list sizes you're likely to have. If it is a concern, and the lists are sorted, you can keep a cursor in each least, and move forward only through them once to make it an O(2n) algorithm.

Increment counters of node and ALL parents using firebase realtime db cloud functions

I'm writing cloud functions for my firebase realtime database (not firestore) using js sdk. These functions increment counters that count the number of users per area. The areas I'm using are geographical and nested (Continent>Country>Region>City). The functions are triggered by the insertion of a user into the users list of a given area (.onCreate). If a user is inserted into the users list of let's say a country, it will automatically be added to the users list of the parent continent.
After tinkering for some time I was only able to come up with a "low-level" non-scalable solution (which by the way works). This means that I need to write additionnal code if I want to add a child area to city for example.
This is a problem because I expect to add child areas in the future.
Question: Is there a way to write a generic cloud function that increments the counters of a node and the counters of all its parent nodes?
I'm quite new to firebase and any help would be really appreciated
Json structure of firebase realtime db
{
"groups" : {
"location" : {
"continents" : {
"EU" : {
"countries" : {
"DE" : {
"created" : "2019-03-25--20:03:34",
"flag" : "/flags/de.svg",
"label" : "Germany",
"level" : 2,
"regions" : {
"BE" : {
"cities" : {
"Berlin" : {
"created" : "2019-03-25--20:03:35",
"label" : "Berlin",
"level" : 3,
"type" : "location",
"usercount" : 1,
"users" : {
"rvDUa5n0oufRFGA9JB7lioom0ac2" : {
"created" : "2019-03-25--20:03:55",
"label" : "Anonymous"
}
}
}
},
"created" : "2019-03-25--20:03:35",
"label" : "Land Berlin",
"level" : 3,
"type" : "location",
"usercount" : 1,
"users" : {
"rvDUa5n0oufRFGA9JB7lioom0ac2" : {
"created" : "2019-03-25--20:03:52",
"label" : "Anonymous"
}
}
}
},
"type" : "location",
"usercount" : 1,
"users" : {
"rvDUa5n0oufRFGA9JB7lioom0ac2" : {
"created" : "2019-03-25--20:03:49",
"label" : "Anonymous"
}
}
}
},
"created" : "2019-03-25--20:03:33",
"label" : "Europe",
"level" : 1,
"type" : "location",
"usercount" : 1,
"users" : {
"rvDUa5n0oufRFGA9JB7lioom0ac2" : {
"created" : "2019-03-25--20:03:46",
"label" : "Anonymous"
}
}
}
}
}
}
}
My cloud functions for user insertion - still need to write for user deletion
exports.onUserAddToContinent = functions.database
.ref('/groups/location/continents/{continentID}/users/{userID}')
.onCreate((snapshot, context) => {
const continentId = context.params.continentID
const counterRef = admin.database().ref('/groups/location/continents/' + continentId + '/usercount');
return counterRef.transaction(usercount => {
return (usercount || 0) + 1
})
})
exports.onUserAddToCountry = functions.database
.ref('/groups/location/continents/{continentID}/countries/{countryID}/users/{userID}')
.onCreate((snapshot, context) => {
const continentId = context.params.continentID
const countryId = context.params.countryID
const counterRef = admin.database().ref('/groups/location/continents/' + continentId + '/countries/' + countryId + '/usercount');
return counterRef.transaction(usercount => {
return (usercount || 0) + 1
})
})
exports.onUserAddToRegion = functions.database
.ref('/groups/location/continents/{continentID}/countries/{countryID}/regions/{regionID}/users/{userID}')
.onCreate((snapshot, context) => {
const continentId = context.params.continentID
const countryId = context.params.countryID
const regionId = context.params.regionID
const counterRef = admin.database().ref('/groups/location/continents/' + continentId + '/countries/' + countryId + '/regions/' + regionId +'/usercount');
return counterRef.transaction(usercount => {
return (usercount || 0) + 1
})
})
exports.onUserAddToCity = functions.database
.ref('/groups/location/continents/{continentID}/countries/{countryID}/regions/{regionID}/cities/{cityID}/users/{userID}')
.onCreate((snapshot, context) => {
const continentId = context.params.continentID
const countryId = context.params.countryID
const regionId = context.params.regionID
const cityId = context.params.cityID
const counterRef = admin.database().ref('/groups/location/continents/' + continentId + '/countries/' + countryId + '/regions/' + regionId +'/cities/'+ cityId + '/usercount');
return counterRef.transaction(usercount => {
return (usercount || 0) + 1
})
})
I feel 'im missing something. There has to be a generic way of doing this.

Match 2 fields in different records Mongoose

Goodmorning
I am trying to match certain fields over a dataset. The dataset contains records like:
{
"token" : "17e0d95f2e2112443cfb09970ae9140e",
"answers" : {
"Yourname" : "Marco",
"youremail" : "marco#me.nl",
"recemail" : "sonja#me.nl"
}
},
{
"token" : "cf5ae65b05249dc6b2a0c99c4cf9688e",
"answers" : {
"yourname" : "Sonja",
"youremail" : "sonja#me.nl",
"recemail" : "marco#me.nl"
}
}
In this case, it should match the two because the recemail (recipients email) matches someone else's email address. And vice versa.
What I am trying to find is how to find these two records (in a larger dataset with more of these matches).
So, Marco's recemail should find Sonja's youremail and these two matches should then be made available to save into another collection, but that's not the important part here.
hope someone can help me with this query
Thanks!

The following code will return an array of 2-entry arrays. Each 2-entry array is made of the sender email and the recipient email. Each pair will appear only once. In other words, you'll get ["marco#me.nl", "sonja#me.nl"] but not ["sonja#me.nl", "marco#me.nl"].
var list = [{
"token" : "17e0d95f2e2112443cfb09970ae9140e",
"answers" : {
"Yourname" : "Marco",
"youremail": "marco#me.nl",
"recemail" : "sonja#me.nl" }
}, {
"token" : "cf5ae65b05249dc6b2a0c99c4cf9688e",
"answers" : {
"yourname" : "Sonja",
"youremail": "sonja#me.nl",
"recemail" : "marco#me.nl" }
}, {
"token" : "fe2c2740e083dfe02cc7e96520a0e079",
"answers" : {
"yourname" : "Joe",
"youremail": "joe#foo.com",
"recemail" : "mike#bar.com" }
}
];
var res = [], sz = list.length;
list.forEach(function(obj, pos) {
for(var i = pos + 1; i < sz; i++) {
if(
list[i].answers.youremail == obj.answers.recemail &&
list[i].answers.recemail == obj.answers.youremail
) {
res.push([ obj.answers.youremail, obj.answers.recemail ]);
}
}
});
console.log(res);

How can I get data in json array by ID

I have a problem, may you help me!
I have a json array:
"category" : [
{
id: 1,
product: [{id : product_1, type : ball}]
},
{
id : 2,
product :[{id : product_2, type : pen}]
}
]
My problem is: if i have a link such as: http://test/category/1 then , How can I do to get product information by category with id = 1 ?
Thanks for any suggestion :)

This is a way to do it in one line and without using for:
function filterById(jsonObject, id) {return jsonObject.filter(function(jsonObject) {return (jsonObject['id'] == id);})[0];}
Then if you want to get, for example, the object with id=2, you just use:
var selectedObject = filterById(yourJson['category'], 2);
And then selectedObject will get this value, as per your example:
{
id : 2,
product :[{id : product_2, type : pen}]
}
There is a downside: Old browsers, such as IE8, don't support filter() so you need to add this polyfill code for old browser compatibility:
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/filter#Polyfill

Assuming your data structure looks like this:
var data = {
"category" : [
{
id: 1,
product: [{id : product_1, type : ball}]
},
{
id : 2,
product :[{id : product_2, type : pen}]
}
]
}
Then, you can find the item in the category array with id == 1 by searching through the array like this:
function findId(data, idToLookFor) {
var categoryArray = data.category;
for (var i = 0; i < categoryArray.length; i++) {
if (categoryArray[i].id == idToLookFor) {
return(categoryArray[i].product);
}
}
}
var item = findId(data, 1);
// item.id, item.type

If you save your array of categories in categories JS variable, you can filter this array based on simple JavaScript (with no jQuery) like that:
var result = categories.filter(function(element){
if (element.id == 2){
return true;
} else {
return false;
}
});
and then in result[0].product you will have array of products that are within specific category.
See this jsfiddle for a proof.
PS. filter() method is not available in all browsers, you may need to apply some code that will make it available if needed and not found. Here is some article on Mozilla Developers Network on the details of filter() and the code you need to make it work on old browsers: MDN: filter().

I think the OP wants to retrieve corresponding data from url.
So the first step is map the url to identifier
var urlParts = window.location.href.split(/\//)
//window.location.href = http://domain.com/category/1
// urlParts = ['http:', '', 'domain.com', 'category', '1']
var id = urlParts.pop();
var category = urlParts.pop();
Then you retrive the data from JSON string with JSON.parse:
var data = JSON.parse('{"category" : [{"id": 1, "product": [{"id" : "product_1", "type" : "ball"}] }, {"id" : 2, "product" :[{"id" : "product_2", "type" : "pen"}] } ]}');
//The data structure
// {"category" : [
// {"id": 1, "product" :
// [
// {"id" : "product_1", "type" : "ball"}
// ]},
// {"id" : 2, "product" :
// [
// {"id" : "product_2", "type" : "pen"}
// ]}
// ]}
At last, you can retrive the data similar #jfriend00's post with id and category
function findId(data, idToLookFor) {
var categoryArray = data.category;
for (var i = 0; i < categoryArray.length; i++) {
if (categoryArray[i].id == idToLookFor) {
return(categoryArray[i].product);
}
}
}
var item = findId(data.category, id);
// item.id, item.type

You might have found the answer, but if you haven't you can simply use the logical OR (||) operator.
In your case, you can use jQuery's ajax() method. To grab your product based on ids just use the below simple logic:
var prodID1 = 1, prodID2 = 2;
if(this.id == prodID || this.id == prodID2) {
//write your JSON data, etc.
//push to array, etc.
}

"category" : [
{
id: 1,
product: [{id : product_1, type : ball}]
},
{
id : 2,
product :[{id : product_2, type : pen}]
}
]
In this scenario I recommend, that you get the array from the Json response using the key. For example if your json response name is : "data" then do "data.category" which will give you an array to loop through.
Then
const allProducts = data.category;
allProducts .forEach((element) => {
//here id is your own id by which you want to compare against the json object
if (element.id == id) {
response.status(200).json(element)
//or you can return this element and capture it for any other operation you desire to do
}
});