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Big Data Analytics Articles
Page 63 of 135
How to validate documents before insert or update in MongoDB?
To validate documents, use the concept of validation. Following is the query −> db.createCollection("demo356", {validator: { ... $and: [ {"FirstName": {$type: "string", $exists: true}} ] ... }}) { "ok" : 1 }Let us create a collection with documents −> db.demo356.insertOne({"FirstName":"Chris"}); { "acknowledged" : true, "insertedId" : ObjectId("5e568d49f8647eb59e5620c7") } > db.demo356.insertOne({"FirstName":909}); 2020-02-26T20:52:58.497+0530 E QUERY [js] WriteError: Document failed validation : WriteError({ "index" : 0, "code" : 121, "errmsg" : "Document failed validation", "op" : { "_id" : ObjectId("5e568d52f8647eb59e5620c8"), "FirstName" : 909 } }) WriteError@src/mongo/shell/bulk_api.js:461:48 Bulk/mergeBatchResults@src/mongo/shell/bulk_api.js:841:49 Bulk/executeBatch@src/mongo/shell/bulk_api.js:906:13 Bulk/this.execute@src/mongo/shell/bulk_api.js:1150:21 DBCollection.prototype.insertOne@src/mongo/shell/crud_api.js:252:9 ...
Read MoreHow to project specific elements in an array field with MongoDB?
To project-specific elements in an array field, use $project. Let us create a collection with documents −>db.demo355.insertOne({"id":101, "details":[{"Name":"Chris", isMarried:1}, {"Name":"David", isMarried:0}, {"Name":"Mike", isMarried:1}]}); { "acknowledged" : true, "insertedId" : ObjectId("5e568928f8647eb59e5620c5") }Display all documents from a collection with the help of find() method −> db.demo355.find().pretty();This will produce the following output −{ "_id" : ObjectId("5e568928f8647eb59e5620c5"), "id" : 101, "details" : [ { "Name" : "Chris", "isMarried" : 1 }, { "Name" : "David", ...
Read MoreMongoDB query for counting number of unique fields grouped by another field?
For this, use aggregate() and group with $group. Let us create a collection with documents −> db.demo354.insertOne({"Name1":"Chris", "Name2":"David"}); { "acknowledged" : true, "insertedId" : ObjectId("5e5685a6f8647eb59e5620c0") } > db.demo354.insertOne({"Name1":"Chris", "Name2":"David"}); { "acknowledged" : true, "insertedId" : ObjectId("5e5685a9f8647eb59e5620c1") } > db.demo354.insertOne({"Name1":"Chris", "Name2":"Bob"}); { "acknowledged" : true, "insertedId" : ObjectId("5e5685aff8647eb59e5620c2") } > db.demo354.insertOne({"Name1":"Carol", "Name2":"John"}); { "acknowledged" : true, "insertedId" : ObjectId("5e5685c4f8647eb59e5620c3") } > db.demo354.insertOne({"Name1":"Carol", "Name2":"John"}); { "acknowledged" : true, "insertedId" : ObjectId("5e5685c5f8647eb59e5620c4") }Display all documents from a collection with the help of find() method −> db.demo354.find();This will produce the following output −{ "_id" ...
Read MoreMongoDB query to find oldest date of three keys in each document
To find the oldest date, use $min in MongoDB aggregate(). Let us create a collection with documents −> db.demo353.insertOne({"Date1":new ISODate("2019-01-10"), "Date2":new ISODate("2016-01-21"), "Date3":new ISODate("2020-04-11")}); { "acknowledged" : true, "insertedId" : ObjectId("5e568261f8647eb59e5620be") } > db.demo353.insertOne({"Date1":new ISODate("2011-11-20"), "Date2":new ISODate("2013-12-10"), "Date3":new ISODate("2014-01-05")}); { "acknowledged" : true, "insertedId" : ObjectId("5e56827ff8647eb59e5620bf") }Display all documents from a collection with the help of find() method −> db.demo353.find();This will produce the following output −{ "_id" : ObjectId("5e568261f8647eb59e5620be"), "Date1" : ISODate("2019-01-10T00:00:00Z"), "Date2" : ISODate("2016-01-21T00:00:00Z"), "Date3" : ISODate("2020-04-11T00:00:00Z") } { "_id" : ObjectId("5e56827ff8647eb59e5620bf"), "Date1" : ISODate("2011-11-20T00:00:00Z"), "Date2" : ISODate("2013-12-10T00:00:00Z"), "Date3" : ISODate("2014-01-05T00:00:00Z") }Following is the query ...
Read MoreMongoDB query to update selected fields
To update selected fields, use UPDATE() in MongoDB. The $set is used to set the new value. Let us create a collection with documents −> db.demo352.insertOne({"Name":"Chris"}); { "acknowledged" : true, "insertedId" : ObjectId("5e55510af8647eb59e5620ba") } > db.demo352.insertOne({"Name":"David"}); { "acknowledged" : true, "insertedId" : ObjectId("5e55510ef8647eb59e5620bb") } > db.demo352.insertOne({"Name":"Bob"}); { "acknowledged" : true, "insertedId" : ObjectId("5e555112f8647eb59e5620bc") } > db.demo352.insertOne({"Name":"Mike"}); { "acknowledged" : true, "insertedId" : ObjectId("5e555115f8647eb59e5620bd") }Display all documents from a collection with the help of find() method −> db.demo352.find();This will produce the following output −{ "_id" : ObjectId("5e55510af8647eb59e5620ba"), "Name" : "Chris" } { "_id" ...
Read MoreHow to find specific array elements in MongoDB document with query and filter with range?
For this, use aggregate() in MongoDB. Let us create a collection with documents −> db.demo351.insertOne( ... { ... ... "_id" : "101", ... "ProductDetails" : [ ... { ... "ProductName" : "Product-1", ... "ProductPrice" :500 ... }, ... { ... "ProductName" : "Product-2", ... "ProductPrice" :400 ... } ... ] ... } ... ); { "acknowledged" : true, "insertedId" : "101" } > db.demo351.insertOne( ... { ... ... ...
Read MoreQuery deeply nested Objects in MongoDB
To query deeply nested objects, use dot(.) notation in MongoDB. Let us create a collection with documents −> db.demo350.insertOne( ... { ... id:101, ... Name: "Chris", ... details: [ ... { ... _id: 1, ... ClientNumber: "10001", ... ClientDetails: [ . ... { ... Name:"David", ... Age:29 ... }, ... ...
Read MoreMongoDB findOneAndUpdate() to update a single document
The findOneAndUpdate() is used to update only a single document in MongoDB. Let us create a collection with documents −db.demo349.insertOne({"Name":"Chris", "Marks":56}); { "acknowledged" : true, "insertedId" : ObjectId("5e55384af8647eb59e5620b4") } > db.demo349.insertOne({"Name":"David", "Marks":78}); { "acknowledged" : true, "insertedId" : ObjectId("5e553853f8647eb59e5620b5") } > db.demo349.insertOne({"Name":"Chris", "Marks":89}); { "acknowledged" : true, "insertedId" : ObjectId("5e55385af8647eb59e5620b6") } > db.demo349.insertOne({"Name":"David", "Marks":54}); { "acknowledged" : true, "insertedId" : ObjectId("5e55385ff8647eb59e5620b7") }Display all documents from a collection with the help of find() method −> db.demo349.find();This will produce the following output −{ "_id" : ObjectId("5e55384af8647eb59e5620b4"), "Name" : "Chris", "Marks" : 56 } { ...
Read MoreQuerying array of Embedded Documents in MongoDB based on Range?
To query an array of embedded documents based on range, use aggregate(). Let us create a collection with documents −> db.demo346.insertOne( ... { ... _id: 101, ... userDetails: [ ... { UserName: "Chris", Score:78}, ... { UserName: "David", Score:68}, ... { UserName: "Bob", Score:88} ... ] ... } ... ); { "acknowledged" : true, "insertedId" : 101 } > db.demo346.insertOne( ... { ... _id: 102, ... userDetails: [ ... ...
Read MoreMongoDB query to find and return subdocument with criteria?
Let us create a collection with documents −> db.demo345.insertOne({ ... "UserName" : "Robert", ... "UserDetails" : [ ... { ... "isMarried" : false, ... "CountryName":"US" ... ... }, ... { ... "isMarried" : true, ... "CountryName":"UK" ... ... }, ... { ... "isMarried" : false, ... ...
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