{"id":9994,"date":"2022-09-21T18:33:22","date_gmt":"2022-09-21T13:03:22","guid":{"rendered":"https:\/\/jassweb.com\/solved\/solved-what-is-the-best-way-to-query-data-conditionally-in-mongodb-node-js\/"},"modified":"2022-09-21T18:33:22","modified_gmt":"2022-09-21T13:03:22","slug":"solved-what-is-the-best-way-to-query-data-conditionally-in-mongodb-node-js","status":"publish","type":"post","link":"https:\/\/jassweb.com\/solved\/solved-what-is-the-best-way-to-query-data-conditionally-in-mongodb-node-js\/","title":{"rendered":"[Solved] What is the best way to query data conditionally in MongoDB (node.js)?"},"content":{"rendered":"

[ad_1]
\n<\/p>\n

\n
\n
<\/div>\n
\n
\n

To come up with a functioning MongoDB query that determines whether a user is part of a group requires an understanding of how you’re structuring your database and groups collection. One way to structure that is like so:<\/p>\n

{\n    \"_id\" : ObjectId(\"594ea5bc4be3b65eeb8705d8\"),\n    \"group_name\": \"...\",\n    \"group_members\": [\n        {\n            \"user_id\": ObjectId(\"<same one from users collection\"), \n            \"user_name\": \"Alice\", \n            \"user_profile_picture\": \"<link_to_imag_url>\"\n        },\n        {\n            \"user_id\": ObjectId(\"<same one from users collection\"),\n            \"user_name\": \"Bob\",\n            \"user_profile_picture\": \"<link_to_imag_url>\"\n        },\n        ....\n    ]\n}\n<\/code><\/pre>\n
Your group document\/object can have attributes for things like it’s name, creation date, description, etc. One of the attributes should be “group_members” which can be used when doing your query to see if a user (based on id) is part of a specific group.<\/p>\n
The MongoDB $elemMatch<\/code><\/a> operator seems like a great choice to satisfy your use case (if you’re using a similar group data structure to example one. Further down on that $elemMatch page is a section on Array of Embedded Documents<\/a>. You can do a query like:<\/p>\n
db.groups.find({\n    _id: ObjectId(\"<id of group you're checking\"),\n    group_members: {\n        $elemMatch: { user_id: ObjectId(\"<user id of user you're checking>\") } \n    }\n})\n<\/code><\/pre>\n
That will return either 1 or 0 results. 1 if there is a group with that _id<\/code> and a group_members<\/code> array that contains an element that has the user id specified, otherwise 0.<\/p>\n
Now to use that in Node, you can use the MongoDB NodeJS Driver<\/a> in conjunction with an Express<\/a> web server:<\/p>\n
var MongoClient = require('mongodb').MongoClient\nvar ObjectID = require('mongodb').ObjectID;\nvar express = require('express');\nvar app = express();\nvar bodyParser = require('body-parser');\n\napp.use(bodyParser.urlencoded({extended: true}));\napp.use(bodyParser.json());\n\n\/\/ Connection URL\nvar url=\"mongodb:\/\/localhost:27017\/test\"; \/\/ change test to whichever db you added the collections to\n\napp.get('\/partOfGroup', (req, res) => {\n    if (req.query.groupId == null || req.query.userId == null) {\n        return res.send('Must include both groupId and userId')\n    } else {\n        MongoClient.connect(url, function(err, db) {\n            var collection = db.collection('groups');\n            collection.findOne({\n                _id: ObjectID(req.query.groupId),\n                group_members: {\n                    $elemMatch: { user_id: req.query.userId}\n                }\n            }, function(err, result) {\n                return res.send(result != null)\n            })\n        })\n    }\n});\n\napp.listen(3000, function () {\n    console.log('Example app listening on port 3000');\n});\n<\/code><\/pre>\n
With that up and running, you can go to the url http:\/\/localhost:3000\/partOfGroup?groupId=594ea5bc4be3b65eeb8705d8&userId=12345<\/a> and it should return true or false depending on if there’s a group with id 594ea5bc4be3b65eeb8705d8 and user with id 12345 in that group.<\/p>\n
From your front-end code, make a request to that url when a logged in user visits a group page, replacing the group id and user id appropriately. The response you get will determine whether to display a “Join” or “Leave” button.<\/p>\n<\/p><\/div>\n
<\/div>\n<\/div>\n
            1<\/span> <\/p><\/div>\n<\/div>\n
[ad_2]<\/p>\n
solved What is the best way to query data conditionally in MongoDB (node.js)? <\/p>\n","protected":false},"excerpt":{"rendered":"
[ad_1] To come up with a functioning MongoDB query that determines whether a user is part of a group requires an understanding of how you’re structuring your database and groups collection. One way to structure that is like so: { “_id” : ObjectId(“594ea5bc4be3b65eeb8705d8”), “group_name”: “…”, “group_members”: [ { “user_id”: ObjectId(“<same one from users collection”), “user_name”: … Read more<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[320],"tags":[1128,902,784],"class_list":["post-9994","post","type-post","status-publish","format-standard","hentry","category-solved","tag-mongodb","tag-node-js","tag-reactjs"],"yoast_head":"\n[Solved] What is the best way to query data conditionally in MongoDB (node.js)? - JassWeb<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/jassweb.com\/solved\/solved-what-is-the-best-way-to-query-data-conditionally-in-mongodb-node-js\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"[Solved] What is the best way to query data conditionally in MongoDB (node.js)? - JassWeb\" \/>\n<meta property=\"og:description\" content=\"[ad_1] To come up with a functioning MongoDB query that determines whether a user is part of a group requires an understanding of how you’re structuring your database and groups collection. One way to structure that is like so: { "_id" : ObjectId("594ea5bc4be3b65eeb8705d8"), "group_name": "...", "group_members": [ { "user_id": ObjectId("<same one from users collection"), "user_name": ... Read more\" \/>\n<meta property=\"og:url\" content=\"https:\/\/jassweb.com\/solved\/solved-what-is-the-best-way-to-query-data-conditionally-in-mongodb-node-js\/\" \/>\n<meta property=\"og:site_name\" content=\"JassWeb\" \/>\n<meta property=\"article:published_time\" content=\"2022-09-21T13:03:22+00:00\" \/>\n<meta name=\"author\" content=\"Kirat\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"Kirat\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"2 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\/\/jassweb.com\/solved\/solved-what-is-the-best-way-to-query-data-conditionally-in-mongodb-node-js\/#article\",\"isPartOf\":{\"@id\":\"https:\/\/jassweb.com\/solved\/solved-what-is-the-best-way-to-query-data-conditionally-in-mongodb-node-js\/\"},\"author\":{\"name\":\"Kirat\",\"@id\":\"https:\/\/jassweb.com\/solved\/#\/schema\/person\/65c9c7b7958150c0dc8371fa35dd7c31\"},\"headline\":\"[Solved] What is the best way to query data conditionally in MongoDB (node.js)?\",\"datePublished\":\"2022-09-21T13:03:22+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\/\/jassweb.com\/solved\/solved-what-is-the-best-way-to-query-data-conditionally-in-mongodb-node-js\/\"},\"wordCount\":301,\"publisher\":{\"@id\":\"https:\/\/jassweb.com\/solved\/#organization\"},\"keywords\":[\"mongodb\",\"node.js\",\"reactjs\"],\"articleSection\":[\"Solved\"],\"inLanguage\":\"en-US\"},{\"@type\":\"WebPage\",\"@id\":\"https:\/\/jassweb.com\/solved\/solved-what-is-the-best-way-to-query-data-conditionally-in-mongodb-node-js\/\",\"url\":\"https:\/\/jassweb.com\/solved\/solved-what-is-the-best-way-to-query-data-conditionally-in-mongodb-node-js\/\",\"name\":\"[Solved] What is the best way to query data conditionally in MongoDB (node.js)? - JassWeb\",\"isPartOf\":{\"@id\":\"https:\/\/jassweb.com\/solved\/#website\"},\"datePublished\":\"2022-09-21T13:03:22+00:00\",\"breadcrumb\":{\"@id\":\"https:\/\/jassweb.com\/solved\/solved-what-is-the-best-way-to-query-data-conditionally-in-mongodb-node-js\/#breadcrumb\"},\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\/\/jassweb.com\/solved\/solved-what-is-the-best-way-to-query-data-conditionally-in-mongodb-node-js\/\"]}]},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\/\/jassweb.com\/solved\/solved-what-is-the-best-way-to-query-data-conditionally-in-mongodb-node-js\/#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\/\/jassweb.com\/solved\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"[Solved] What is the best way to query data conditionally in MongoDB (node.js)?\"}]},{\"@type\":\"WebSite\",\"@id\":\"https:\/\/jassweb.com\/solved\/#website\",\"url\":\"https:\/\/jassweb.com\/solved\/\",\"name\":\"JassWeb\",\"description\":\"Build High-quality Websites\",\"publisher\":{\"@id\":\"https:\/\/jassweb.com\/solved\/#organization\"},\"potentialAction\":[{\"@type\":\"SearchAction\",\"target\":{\"@type\":\"EntryPoint\",\"urlTemplate\":\"https:\/\/jassweb.com\/solved\/?s={search_term_string}\"},\"query-input\":{\"@type\":\"PropertyValueSpecification\",\"valueRequired\":true,\"valueName\":\"search_term_string\"}}],\"inLanguage\":\"en-US\"},{\"@type\":\"Organization\",\"@id\":\"https:\/\/jassweb.com\/solved\/#organization\",\"name\":\"Jass Web\",\"url\":\"https:\/\/jassweb.com\/solved\/\",\"logo\":{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\/\/jassweb.com\/solved\/#\/schema\/logo\/image\/\",\"url\":\"https:\/\/jassweb.com\/wp-content\/uploads\/2021\/02\/jass-website-logo-1.png\",\"contentUrl\":\"https:\/\/jassweb.com\/wp-content\/uploads\/2021\/02\/jass-website-logo-1.png\",\"width\":693,\"height\":132,\"caption\":\"Jass Web\"},\"image\":{\"@id\":\"https:\/\/jassweb.com\/solved\/#\/schema\/logo\/image\/\"}},{\"@type\":\"Person\",\"@id\":\"https:\/\/jassweb.com\/solved\/#\/schema\/person\/65c9c7b7958150c0dc8371fa35dd7c31\",\"name\":\"Kirat\",\"image\":{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\/\/jassweb.com\/solved\/#\/schema\/person\/image\/\",\"url\":\"https:\/\/jassweb.com\/solved\/wp-content\/litespeed\/avatar\/1261af3c9451399fa1336d28b98ea3bb.jpg?ver=1776403586\",\"contentUrl\":\"https:\/\/jassweb.com\/solved\/wp-content\/litespeed\/avatar\/1261af3c9451399fa1336d28b98ea3bb.jpg?ver=1776403586\",\"caption\":\"Kirat\"},\"sameAs\":[\"http:\/\/jassweb.com\"],\"url\":\"https:\/\/jassweb.com\/solved\/author\/jaspritsinghghumangmail-com\/\"}]}<\/script>\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"[Solved] What is the best way to query data conditionally in MongoDB (node.js)? - JassWeb","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/jassweb.com\/solved\/solved-what-is-the-best-way-to-query-data-conditionally-in-mongodb-node-js\/","og_locale":"en_US","og_type":"article","og_title":"[Solved] What is the best way to query data conditionally in MongoDB (node.js)? - JassWeb","og_description":"[ad_1] To come up with a functioning MongoDB query that determines whether a user is part of a group requires an understanding of how you’re structuring your database and groups collection. One way to structure that is like so: { \"_id\" : ObjectId(\"594ea5bc4be3b65eeb8705d8\"), \"group_name\": \"...\", \"group_members\": [ { \"user_id\": ObjectId(\"<same one from users collection\"), \"user_name\": ... Read more","og_url":"https:\/\/jassweb.com\/solved\/solved-what-is-the-best-way-to-query-data-conditionally-in-mongodb-node-js\/","og_site_name":"JassWeb","article_published_time":"2022-09-21T13:03:22+00:00","author":"Kirat","twitter_card":"summary_large_image","twitter_misc":{"Written by":"Kirat","Est. reading time":"2 minutes"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"Article","@id":"https:\/\/jassweb.com\/solved\/solved-what-is-the-best-way-to-query-data-conditionally-in-mongodb-node-js\/#article","isPartOf":{"@id":"https:\/\/jassweb.com\/solved\/solved-what-is-the-best-way-to-query-data-conditionally-in-mongodb-node-js\/"},"author":{"name":"Kirat","@id":"https:\/\/jassweb.com\/solved\/#\/schema\/person\/65c9c7b7958150c0dc8371fa35dd7c31"},"headline":"[Solved] What is the best way to query data conditionally in MongoDB (node.js)?","datePublished":"2022-09-21T13:03:22+00:00","mainEntityOfPage":{"@id":"https:\/\/jassweb.com\/solved\/solved-what-is-the-best-way-to-query-data-conditionally-in-mongodb-node-js\/"},"wordCount":301,"publisher":{"@id":"https:\/\/jassweb.com\/solved\/#organization"},"keywords":["mongodb","node.js","reactjs"],"articleSection":["Solved"],"inLanguage":"en-US"},{"@type":"WebPage","@id":"https:\/\/jassweb.com\/solved\/solved-what-is-the-best-way-to-query-data-conditionally-in-mongodb-node-js\/","url":"https:\/\/jassweb.com\/solved\/solved-what-is-the-best-way-to-query-data-conditionally-in-mongodb-node-js\/","name":"[Solved] What is the best way to query data conditionally in MongoDB (node.js)? - JassWeb","isPartOf":{"@id":"https:\/\/jassweb.com\/solved\/#website"},"datePublished":"2022-09-21T13:03:22+00:00","breadcrumb":{"@id":"https:\/\/jassweb.com\/solved\/solved-what-is-the-best-way-to-query-data-conditionally-in-mongodb-node-js\/#breadcrumb"},"inLanguage":"en-US","potentialAction":[{"@type":"ReadAction","target":["https:\/\/jassweb.com\/solved\/solved-what-is-the-best-way-to-query-data-conditionally-in-mongodb-node-js\/"]}]},{"@type":"BreadcrumbList","@id":"https:\/\/jassweb.com\/solved\/solved-what-is-the-best-way-to-query-data-conditionally-in-mongodb-node-js\/#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/jassweb.com\/solved\/"},{"@type":"ListItem","position":2,"name":"[Solved] What is the best way to query data conditionally in MongoDB (node.js)?"}]},{"@type":"WebSite","@id":"https:\/\/jassweb.com\/solved\/#website","url":"https:\/\/jassweb.com\/solved\/","name":"JassWeb","description":"Build High-quality Websites","publisher":{"@id":"https:\/\/jassweb.com\/solved\/#organization"},"potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/jassweb.com\/solved\/?s={search_term_string}"},"query-input":{"@type":"PropertyValueSpecification","valueRequired":true,"valueName":"search_term_string"}}],"inLanguage":"en-US"},{"@type":"Organization","@id":"https:\/\/jassweb.com\/solved\/#organization","name":"Jass Web","url":"https:\/\/jassweb.com\/solved\/","logo":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/jassweb.com\/solved\/#\/schema\/logo\/image\/","url":"https:\/\/jassweb.com\/wp-content\/uploads\/2021\/02\/jass-website-logo-1.png","contentUrl":"https:\/\/jassweb.com\/wp-content\/uploads\/2021\/02\/jass-website-logo-1.png","width":693,"height":132,"caption":"Jass Web"},"image":{"@id":"https:\/\/jassweb.com\/solved\/#\/schema\/logo\/image\/"}},{"@type":"Person","@id":"https:\/\/jassweb.com\/solved\/#\/schema\/person\/65c9c7b7958150c0dc8371fa35dd7c31","name":"Kirat","image":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/jassweb.com\/solved\/#\/schema\/person\/image\/","url":"https:\/\/jassweb.com\/solved\/wp-content\/litespeed\/avatar\/1261af3c9451399fa1336d28b98ea3bb.jpg?ver=1776403586","contentUrl":"https:\/\/jassweb.com\/solved\/wp-content\/litespeed\/avatar\/1261af3c9451399fa1336d28b98ea3bb.jpg?ver=1776403586","caption":"Kirat"},"sameAs":["http:\/\/jassweb.com"],"url":"https:\/\/jassweb.com\/solved\/author\/jaspritsinghghumangmail-com\/"}]}},"_links":{"self":[{"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/posts\/9994","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/comments?post=9994"}],"version-history":[{"count":0,"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/posts\/9994\/revisions"}],"wp:attachment":[{"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/media?parent=9994"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/categories?post=9994"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/tags?post=9994"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}