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Articles on Trending Technologies
Technical articles with clear explanations and examples
MongoDB query to find multiple matchings inside array of objects?
To find multiple matching conditions inside an array of objects in MongoDB, use $and operator combined with $elemMatch and $regex. The $and performs a logical AND operation on multiple expressions, while $elemMatch matches documents containing an array field with at least one element matching all criteria. Syntax db.collection.find({ "$and": [ { "arrayField": { "$elemMatch": { "field1": { $regex: /pattern/i } } } }, { "arrayField": { "$elemMatch": { "field2": { $regex: /pattern/i } } } } ...
Read MoreHow to search date between two dates in MongoDB?
To search date between two dates in MongoDB, use $gte and $lt operators. The $gte operator matches dates greater than or equal to the start date, while $lt matches dates less than the end date. Syntax db.collection.find({ dateField: { $gte: new ISODate("start-date"), $lt: new ISODate("end-date") } }); Sample Data Let us create a collection with documents ? db.demo524.insertMany([ {"EndDate": new ISODate("2020-01-19")}, ...
Read MoreWhy does my MongoDB group query return always 0 in float conversion? How to fix it?
When MongoDB group queries return 0 during float conversion, it's typically because string values aren't being properly converted to numbers. Use parseFloat() or MongoDB's $toDouble operator to convert string numbers to actual numeric types. Syntax // Using parseFloat() in forEach db.collection.find({}).forEach(function(doc) { doc.field = parseFloat(doc.field); db.collection.save(doc); }); // Using $toDouble in aggregation db.collection.aggregate([ { $addFields: { "field": { $toDouble: "$field" } } } ]); Sample Data db.demo523.insertOne({ "details": { ...
Read MoreGet distinct pair of objects with all subdocuments in MongoDB?
To get a distinct pair of objects with all subdocuments in MongoDB, use the $group aggregation operator to group documents by a specific field and aggregate their values. This technique helps combine duplicate entries into unique pairs with consolidated data. Syntax db.collection.aggregate([ { $group: { _id: "$fieldToGroupBy", aggregatedField: { $operator: "$fieldToAggregate" } } ...
Read MoreHow to get latest set of data from a MongoDB collection based on the date records?
To get the latest set of data from MongoDB collection based on date records, use sort() with -1 for descending order. For a single latest document, combine with limit(1). Syntax // Get all records sorted by date (latest first) db.collection.find().sort({"dateField": -1}); // Get only the latest record db.collection.find().sort({"dateField": -1}).limit(1); Sample Data db.demo521.insertMany([ {"PurchaseDate": new ISODate("2019-01-10"), "ProductName": "Product-1"}, {"PurchaseDate": new ISODate("2020-04-05"), "ProductName": "Product-10"}, {"PurchaseDate": new ISODate("2010-05-08"), "ProductName": "Product-4"}, {"PurchaseDate": new ISODate("2020-02-21"), "ProductName": "Product-3"} ]); ...
Read MoreText search in MongoDB with Regular Expression
For text search in MongoDB with Regular Expression, use $regex operator to match patterns within string fields. This allows you to search for documents containing specific text patterns or substrings. Syntax db.collection.find({ "fieldName": { $regex: /pattern/ } }); // Alternative syntax db.collection.find({ "fieldName": { $regex: "pattern", $options: "i" } }); Sample Data db.demo519.insertMany([ {"Value": "50, 60, 70"}, {"Value": "80, 90, 50"}, {"Value": "10, 30, 40"} ]); { ...
Read MoreHow can I change the field name in MongoDB?
To change the field name in MongoDB, use the $project operator in an aggregation pipeline. This creates a projection with the new field name while mapping the value from the original field. Syntax db.collection.aggregate([ { $project: { "newFieldName": "$originalFieldName" } } ]); Create Sample Data Let us create a collection with documents − db.demo517.insertMany([ { "Name": "Chris Brown" }, { "Name": "David Miller" }, { "Name": "John Doe" } ]); { ...
Read MoreUpdate the last row with search criteria in MongoDB?
To update the last row that matches specific search criteria in MongoDB, use the findAndModify() method with a sort parameter to identify the most recent document. Syntax db.collection.findAndModify({ query: { field: "value" }, sort: { _id: -1 }, update: { $set: { field: "newValue" } }, new: true }); Sample Data db.demo516.insertMany([ { "Name": "John", "Age": 22, "Score": 56 }, { "Name": "John", "Age": 23, "Score": 67 }, ...
Read MoreMongoDB: Find name similar to Regular Expression input?
To find names similar to a regular expression input in MongoDB, use the $regex operator with the $options parameter for case-insensitive matching. Syntax db.collection.find({ "fieldName": { $regex: "pattern", $options: "i" } }); Sample Data db.demo514.insertMany([ {"Information": {"FullName": "John Doe"}}, {"Information": {"FullName": "John Smith"}}, {"Information": {"FullName": "john doe"}}, {"Information": {"FullName": "Chris Brown"}} ]); ...
Read MoreSum the score of duplicate column values in MongoDB documents?
To sum values of duplicate column entries in MongoDB, use the $group stage with $sum aggregation operator. This groups documents by a field and calculates the total of specified numeric fields. Syntax db.collection.aggregate([ { $group: { _id: "$groupingField", field1Sum: { $sum: "$field1" }, field2Sum: { $sum: "$field2" } ...
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