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Articles by Ankith Reddy
Page 27 of 73
Return True if a document exists in MongoDB?
To check if a document exists in MongoDB, use the find() method with count() or limit(1) to return a boolean result. The count() > 0 approach returns true if documents match the query criteria. Syntax db.collection.find(query).count() > 0 Create Sample Data First, let's create a collection with sample documents ? db.documentExistsOrNotDemo.insertMany([ {"UserId": 101, "UserName": "John"}, {"UserId": 102, "UserName": "Chris"}, {"UserId": 102, "UserName": "Robert"} ]); { "acknowledged": true, "insertedIds": [ ...
Read MoreGetting a distinct aggregation of an array field across indexes
To get a distinct aggregation of an array field across indexes in MongoDB, use the distinct() method on the array field. MongoDB will automatically utilize any existing index on that field to optimize the operation. Syntax db.collection.distinct("arrayFieldName") Sample Data Let's create a collection with documents containing array fields ? db.distinctAggregation.insertMany([ { "UserName": "Larry", "UserPost": ["Hi", "Hello"] }, { ...
Read MoreCan I get the first item in a Cursor object in MongoDB?
Yes, you can get the first item in a cursor object in MongoDB using the findOne() method or by applying the limit(1) method to a cursor. Syntax // Method 1: Using findOne() db.collection.findOne(); db.collection.findOne({condition}); // Method 2: Using find().limit(1) db.collection.find().limit(1); Sample Data db.getFirstItemDemo.insertMany([ {"CustomerName": "Chris", "CustomerAge": 28}, {"CustomerName": "Larry", "CustomerAge": 26}, {"CustomerName": "Robert", "CustomerAge": 29}, {"CustomerName": "David", "CustomerAge": 39} ]); { "acknowledged": true, "insertedIds": [ ...
Read MoreHow to remove document on the basis of _id in MongoDB?
To remove a document based on its _id in MongoDB, use the remove() method with the ObjectId as the matching criteria. Each document has a unique _id field that serves as the primary key. Syntax db.collectionName.remove({"_id": ObjectId("yourObjectId")}); Sample Data Let us first create a collection with sample documents ? db.removeDocumentOnBasisOfId.insertMany([ {"UserName": "Larry", "UserAge": 23, "UserCountryName": "US"}, {"UserName": "Sam", "UserAge": 21, "UserCountryName": "UK"}, {"UserName": "Chris", "UserAge": 24, "UserCountryName": "US"}, {"UserName": "Robert", "UserAge": 26, "UserCountryName": "UK"}, ...
Read MoreHow to search document in MongoDB by _id
To search a document in MongoDB by _id, you need to use the ObjectId() function to wrap the _id value, since MongoDB stores document IDs as ObjectId objects. Syntax db.collectionName.find({"_id": ObjectId("your_object_id_here")}); Create Sample Data Let us create a collection with sample documents ? db.searchDocumentDemo.insertMany([ {"UserId": 1, "UserName": "Larry"}, {"UserId": 2, "UserName": "Mike"}, {"UserId": 3, "UserName": "David"}, {"UserId": 4, "UserName": "Chris"}, {"UserId": 5, "UserName": "Robert"}, {"UserId": 6, "UserName": "Sam"} ...
Read MoreHow to detect HTML5 audio MP3 support
To detect HTML5 audio MP3 support, use the Modernizr library. Modernizr is a JavaScript library that detects HTML5 and CSS3 features in the user's browser. As stated in the official specification, Modernizr provides comprehensive feature detection capabilities for modern web technologies. For detecting HTML5 audio MP3 support, you can also check the User-Agent to detect which browser is used, though this method is less reliable than feature detection. JavaScript Detection Method You can use JavaScript to test HTML5 audio MP3 support directly − function canPlayMP3() { var audio = document.createElement('audio'); ...
Read MoreThe:last-child selector not working as expected in HTML5
The :last-child CSS selector selects an element only if it is the last child of its parent, regardless of type or class. A common mistake is expecting it to select the last element of a specific type or class within a parent, but that is not how it works. This is why :last-child often does not behave as expected. When :last-child Works The :last-child selector works when the target element is literally the very last child of its parent. For example, if your selector is a:last-child, it matches only if an tag is the last child inside its parent ...
Read MoreThe contains() method of AbstractSequentialList in Java
The contains() method of AbstractSequentialList in Java is used to check whether an element is in the Collection.The syntax is as followspublic boolean contains(Object ob)Here, ob is the element to be checked. To work with the AbstractSequentialList class in Java, you need to import the following packageimport java.util.AbstractSequentialList;The following is an example to implement AbstractSequentialList contains() method in JavaExampleimport java.util.LinkedList; import java.util.AbstractSequentialList; public class Demo { public static void main(String[] args) { AbstractSequentialList absSequential = new LinkedList(); absSequential.add(250); absSequential.add(320); ...
Read MoreDoubleStream of() method in Java
The DoubleStream class in Java the following two forms of the of() methodThe following of() method returns a sequential DoubleStream containing a single element. Here is the syntaxstatic DoubleStream of(double t)Here, parameter t is the single element.The following of() method returns a sequential ordered stream whose elements are the specified valuesstatic DoubleStream of(double… values)Here, the parameter values are the elements of the new stream.To use the DoubleStream class in Java, import the following packageimport java.util.stream.DoubleStream;The following is an example to implement DoubleStream of() method in JavaExampleimport java.util.stream.DoubleStream; public class Demo { public static void main(String[] args) { ...
Read MoreArrayBlockingQueue size() Method in Java
To get the number of elements in the queue, use the size() method of the ArrayBlockingQueue class.The syntax is as followsint size()To work with ArrayBlockingQueue class, you need to import the following packageimport java.util.concurrent.ArrayBlockingQueue;The following is an example to implement size() method of Java ArrayBlockingQueue classExampleimport java.util.concurrent.ArrayBlockingQueue; public class Demo { public static void main(String[] args) throws InterruptedException { ArrayBlockingQueue q = new ArrayBlockingQueue(10); q.add(200); q.add(310); q.add(400); ...
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