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Big Data Analytics Articles
Page 60 of 135
Fix: MongoDB Robomongo: db.data.find(...).collation is not a function?
The collation feature was introduced in MongoDB version 3.4. If you're encountering the error "collation is not a function", you're likely using an older MongoDB version or an outdated client like Robomongo that doesn't support this feature. Check MongoDB Version First, verify your MongoDB version to ensure it's 3.4 or higher ? db.version() 4.0.5 Create Sample Data Let's create a collection with an index that uses collation and insert test documents ? db.collationExample.createIndex( {Value: 1}, {collation: {locale: "en", strength: ...
Read MoreCalculating average value per document with sort in MongoDB?
To calculate the average value per document in MongoDB, use the aggregation framework with $addFields and $avg operators. You can combine this with $sort to order results by the calculated average. Syntax db.collection.aggregate([ { $addFields: { "avgField": { $avg: "$arrayField" } } }, { $sort: { "avgField": 1 } } ]); Sample Data db.calculateAverage.insertMany([ { "Value": [10, 20, 80] }, { "Value": [12, 15, 16] }, { "Value": [30, 35, 40] } ]); ...
Read MorePromote subfields to top level in projection without listing all keys in MongoDB?
To promote subfields to top level in projection without listing all keys in MongoDB, use $replaceRoot with $arrayToObject and $objectToArray operators. This technique flattens nested objects by converting them to arrays and reconstructing them at the root level. Syntax db.collection.aggregate([ { "$replaceRoot": { "newRoot": { "$arrayToObject": { ...
Read MoreDeleting specific record from an array nested within another array in MongoDB
To delete specific record from an array nested within another array in MongoDB, use the $pull operator combined with the $ positional operator to target the correct parent array element and remove the matching nested document. Syntax db.collection.update( { "parentArray.field": "matchValue" }, { $pull: { "parentArray.$.nestedArray": { "field": "valueToDelete" } } } ); Sample Data db.demo213.insertOne({ "id": 101, "details1": [ { ...
Read MoreFinding a MongoDB document through a word
To find a MongoDB document through a word, use the find() method with regular expression pattern matching. The /word/i syntax performs case-insensitive search for the specified word within field values. Syntax db.collection.find({ "fieldName": /searchWord/i }); Create Sample Data db.demo212.insertMany([ {"details": [{"Name": "John Doe"}]}, {"details": [{"Name": "Chris Brown"}]}, {"details": [{"Name": "Robert doe"}]} ]); { "acknowledged": true, "insertedIds": [ ObjectId("5e3e2c7603d395bdc21346ff"), ...
Read MoreHow do you test if two external values are equal in a MongoDB criteria object?
To test if two external values are equal in a MongoDB criteria object, you can use the $type operator combined with a JavaScript expression that evaluates the equality condition and returns different BSON type numbers. Syntax db.collection.find({ field: "value", field: { $type: baseNumber + (value1 === value2) } }); Sample Data db.demo211.insertMany([ { id: 101, "Name": "Chris" }, { id: 102, "Name": null } ]); { "acknowledged": true, ...
Read MoreGet the count of a specific value in MongoDB
To get the count of a specific value in MongoDB, use the aggregate() method with $unwind and $group stages to count occurrences of array elements or use $size with $filter for a more efficient approach. Syntax db.collection.aggregate([ { $unwind: "$arrayField" }, { $match: { "arrayField.field": "targetValue" } }, { $group: { _id: "$_id", count: { $sum: 1 } } } ]); Sample Data db.demo210.insertOne({ details: [ { ClientName: "Robert" ...
Read MoreMongoDB query to convert the field value and create datetime day of month during projection?
To convert a field value and create datetime day of month during projection in MongoDB, use aggregate() with $unwind to flatten arrays and $dayOfMonth to extract the day from converted timestamps. Syntax db.collection.aggregate([ { "$unwind": "$arrayField" }, { "$project": { "fieldName": 1, "DayOfMonth": { ...
Read MoreSpecify a return format for data in MongoDB
In MongoDB, you can specify a custom return format for your data using aggregation operators like $addToSet. This operator collects unique values from multiple documents and returns them as an array, eliminating duplicates. Syntax db.collection.aggregate([ { "$group": { "_id": null, "fieldName": { "$addToSet": "$sourceField" } } }, ...
Read MoreMongoDB query to determine if a specific value does not exist?
To determine if a specific value does not exist, use the $ne (not equal) operator in MongoDB. This operator matches documents where the field value does not equal the specified value. Syntax db.collection.find({ "field": { "$ne": "value" } }) Sample Data db.demo206.insertMany([ { "ClientDetails": [ { "Name": "Chris", ...
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