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Articles on Trending Technologies
Technical articles with clear explanations and examples
Query MongoDB subdocument to print on one line?
To display subdocuments in one line format, use $unwind along with aggregate() to flatten array elements, then iterate through results with a custom function. Syntax db.collection.aggregate([ { $match: { "field": "value" } }, { $unwind: "$arrayField" } ]).forEach(function(doc) { print(doc.field1 + ", " + doc.arrayField.subfield + ", " + doc.arrayField.subfield2); }); Sample Data db.demo183.insertOne({ "_id": "110", "DueDate": ISODate("2020-02-04T01:10:42.000Z"), "ProductDetails": [ { ...
Read MoreMongoDB query to search date records using only Month and Day
To search MongoDB documents using only month and day while ignoring the year, use the $where operator with JavaScript functions like getMonth() and getDate(). Syntax db.collection.find({ $where: function() { return this.dateField.getMonth() == monthValue && this.dateField.getDate() == dayValue; } }); Sample Data db.demo181.insertMany([ {"ShippingDate": new ISODate("2020-01-10")}, {"ShippingDate": new ISODate("2019-12-11")}, {"ShippingDate": ...
Read MoreHow to find latest entries in array over all MongoDB documents?
To find latest entries in array over all MongoDB documents, use the aggregate() method with $unwind to flatten arrays, $sort to order by the desired field, and $limit to get the top entries. Syntax db.collection.aggregate([ { "$unwind": "$arrayField" }, { "$sort": { "arrayField.sortField": -1 } }, { "$limit": numberOfEntries } ]); Sample Data db.demo179.insertMany([ { "Name": "Chris", "Details": [ ...
Read MoreMongoDB query to fetch date records (ISODate format) in a range
To fetch date records within a specific range from MongoDB documents containing ISODate format dates, use range operators like $gte, $lte, $gt, and $lt in your queries, or aggregation pipeline operators for more complex date filtering. Syntax // Basic date range query db.collection.find({ "dateField": { "$gte": ISODate("start_date"), "$lte": ISODate("end_date") } }); // Aggregation with time-based filtering db.collection.aggregate([ { "$redact": { ...
Read MoreMongoDB query to add a document in an already created collection
To add a document to an existing collection in MongoDB, use the $push operator. This operator appends new documents to an existing array field within a document. Syntax db.collection.update( { "field": "value" }, { $push: { "arrayField": { newDocument } } } ); Sample Data Let's create a collection with sample documents ? db.demo177.insertOne({ "Id": "101", "details": [ { "StudentName": "Chris", ...
Read MoreGet substring in MongoDB aggregate
To extract substring in MongoDB aggregation pipelines, use the $substr operator within the $project stage. This operator extracts a portion of a string starting from a specified position and length. Syntax db.collection.aggregate([ { $project: { fieldName: { $substr: ["$sourceField", startIndex, length] } } } ]) Sample Data db.demo176.insertMany([ {"ProductName": "PRODUCT-1"}, ...
Read MoreHow do I use MongoDB to count only collections that match two fields?
To count documents in MongoDB that match multiple field conditions, use the count() method with a query document containing all required field−value pairs. MongoDB will return the count of documents where all specified conditions are satisfied. Syntax db.collection.count({ "field1": "value1", "field2": "value2" }); Sample Data db.demo175.insertMany([ {"EmployeeName": "Bob", "isMarried": "YES"}, {"EmployeeName": "David", "isMarried": "NO"}, {"EmployeeName": "Mike", "isMarried": "YES"}, {"EmployeeName": "Sam", "isMarried": "NO"} ]); { ...
Read MoreEvaluate one of more values from a MongoDB collection with documents
To evaluate one or more values from a MongoDB collection, use the $or operator with the find() method. The $or operator performs a logical OR operation on an array of expressions and returns documents that match at least one of the conditions. Syntax db.collection.find({ $or: [ { "field1": "value1" }, { "field2": "value2" }, { "fieldN": "valueN" } ] }); Sample Data ...
Read MoreFind a value in lowercase from a MongoDB collection with documents
To find a value in lowercase from a MongoDB collection, use the toLowerCase() method in JavaScript when constructing your query. This allows you to search for documents where a field matches a specific value in lowercase format. Syntax db.collection.find({"fieldName": "VALUE".toLowerCase()}); Sample Data Let us create a collection with documents containing subject names in different cases ? db.demo172.insertMany([ {"SubjectName": "MySQL"}, {"SubjectName": "mongodb"}, {"SubjectName": "MongoDB"} ]); { "acknowledged": true, "insertedIds": [ ...
Read MoreHow to re-map the fields of a MongoDB collection?
To re-map the fields of a MongoDB collection, use $rename operator with update() or updateMany(). This operator allows you to rename field names across documents in your collection. Syntax db.collection.updateMany( {}, { $rename: { "oldFieldName": "newFieldName" } } ); Sample Data Let us create a collection with sample documents ? db.demo171.insertMany([ { "Name": "Chris", "Details": { ...
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