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Articles by AmitDiwan
Page 585 of 840
Querying array of Embedded Documents in MongoDB based on Range?
To query an array of embedded documents based on range, use the $filter operator within an aggregation pipeline. This allows filtering array elements that match specific criteria while preserving the document structure. Syntax db.collection.aggregate([ { $addFields: { "arrayField": { $filter: { ...
Read MoreMongoDB query to find and return subdocument with criteria?
To find and return subdocuments that match specific criteria in MongoDB, use the aggregation pipeline with $match to filter documents and $filter to return only matching subdocuments from arrays. Syntax db.collection.aggregate([ { $match: { "fieldName": "value" } }, { $addFields: { "arrayField": { $filter: { ...
Read MoreHow to query objects with the longest time period in MongoDB?
To query objects with the longest time period in MongoDB, use the aggregation pipeline with $addFields to calculate the duration, $sort to order by longest period, and $limit to get the top result. Syntax db.collection.aggregate([ { $addFields: { duration: { $subtract: [ { $toDate: "$endDate" }, { $toDate: "$startDate" } ] } } }, { $sort: { duration: -1 } }, { $limit: 1 } ]); Create Sample Data ...
Read MoreHow do you convert an array of ObjectIds into an array of embedded documents with a field containing the original array element value?
To convert an array of ObjectIds into an array of embedded documents with a field containing the original array element value, use the $map operator within an aggregation pipeline. This transformation embeds each original array element as a value within a new document structure. Syntax db.collection.aggregate([ { $addFields: { arrayField: { $map: { ...
Read MoreMongoDB query to get only specific fields in nested array documents?
To get only specific fields in nested array documents in MongoDB, use $filter with $project in an aggregation pipeline to match conditions and extract required data from deeply nested arrays. Syntax db.collection.aggregate([ { $project: { "field": { $filter: { ...
Read MoreMongoDB query to find value in array with multiple criteria (range)
To find values in an array within a specific range in MongoDB, use $elemMatch with $gt and $lt operators. This allows you to match documents where at least one array element satisfies multiple criteria. Syntax db.collection.find({ "arrayField": { "$elemMatch": { "field": { "$gt": minValue, ...
Read MoreMongoDB findById returning a list of documents instead of a single result? How to get only a single document?
To get only a single result instead of a list when querying by ID in MongoDB, use the findOne() method instead of find(). The findOne() method returns exactly one document that matches your query criteria. Syntax db.collection.findOne({_id: ObjectId("id_value")}) Sample Data Let us create a collection with documents − db.demo340.insertMany([ {_id: 1, "Name": "Chris", Age: 21}, {_id: 2, "Name": "David", Age: 23}, {_id: 3, "Name": "Bob", Age: 20}, {_id: 4, "Name": "Sam", Age: 19} ]); ...
Read MoreZip two arrays and create new array of object in a reshaped form with MongoDB
To zip two arrays and create a new array of objects in MongoDB, use the $zip operator within an aggregation pipeline. This combines elements from multiple arrays at corresponding positions into a single reshaped structure. Syntax db.collection.aggregate([ { $project: { "newFieldName": { $map: { ...
Read MoreWorking with MongoDB concatArrays in project on existing multi-array field
The $concatArrays operator is used to concatenate arrays and return the concatenated array. When working with multi-dimensional arrays, you can combine it with $reduce to flatten and concatenate nested arrays. Syntax { "$project": { "newFieldName": { "$reduce": { "input": "$arrayField", "initialValue": [], "in": { "$concatArrays": ["$$this", "$$value"] } } } ...
Read MoreHow to calculate sum in MongoDB with aggregate()?
To calculate sum in MongoDB, use the $sum operator along with the aggregate() method. The $sum operator is used within a $group stage to calculate the total of numeric field values across documents. Syntax db.collection.aggregate([ { $group: { _id: null, totalFieldName: { $sum: "$fieldName" } } } ]); ...
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