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Articles on Trending Technologies
Technical articles with clear explanations and examples
Add a field to an embedded document in an array in MongoDB?
To add a field to an embedded document in an array in MongoDB, use the $set operator combined with the $ positional operator and $elemMatch to target the specific array element. Syntax db.collection.update( { "arrayField": { $elemMatch: { "matchField": "value" } } }, { $set: { "arrayField.$.newField": "newValue" } } ); Sample Data Let us create a collection with documents ? db.addAFieldDemo.insertOne({ "ClientName": "Larry", "ClientCountryName": "US", "ClientOtherDetails": [ ...
Read MoreCalculate average of ratings in array and then include the field to original document in MongoDB?
To calculate the average of ratings in an array and include this field in the original document in MongoDB, use the $addFields stage with $avg operator in an aggregation pipeline. This adds a computed field without modifying the original document structure. Syntax db.collection.aggregate([ { $addFields: { averageField: { $avg: "$arrayField.numericField" } } } ]); Sample Data db.averageOfRatingsInArrayDemo.insertOne({ ...
Read MoreMatch element in array of MongoDB?
To match elements in arrays in MongoDB, you can use the $or operator to search for documents where any array element matches one or more conditions. This approach is useful when you want to find documents containing arrays with specific field values. Syntax db.collection.find({ $or: [ {"arrayField.subfield1": "value1"}, {"arrayField.subfield2": "value2"} ] }).limit(1); Sample Data db.matchElementInArrayDemo.insertMany([ { "StudentName": ...
Read MoreHow to get a specific object from array of objects inside specific MongoDB document?
To get a specific object from array of objects inside a MongoDB document, use the positional operator $ in the projection to return only the matched array element. Syntax db.collection.find( { "arrayField.subField": "matchValue" }, { "_id": 0, "arrayField.$": 1 } ); Sample Data Let us create a collection with documents − db.getASpecificObjectDemo.insertOne({ _id: 1, "CustomerName": "Larry", "CustomerDetails": { "CustomerPurchaseDescription": [ ...
Read MoreQuery to retrieve multiple items in an array in MongoDB?
To retrieve multiple items in an array in MongoDB, use the aggregation framework with $unwind, $match, and $group operators to filter and reconstruct array elements based on specific criteria. Syntax db.collection.aggregate([ { $unwind: "$arrayField" }, { $match: { "arrayField.field": { $in: [values] } } }, { $group: { "_id": "$_id", "arrayField": { $push: "$arrayField" } } } ]); Sample Data db.retrieveMultipleDemo.insertOne({ "UserDetails": [ { "_id": "101", "UserName": "John", "UserAge": ...
Read MoreHow to search for documents based on the value of adding two properties in MongoDB?
To search for documents based on the value of adding two properties in MongoDB, use the aggregation framework with $add operator to calculate the sum and $match to filter results based on the calculated value. Syntax db.collection.aggregate([ { $project: { totalValue: { $add: ["$field1", "$field2"] } } }, { $match: { totalValue: { $operator: value } } } ]); Sample Data db.searchDocumentsDemo.insertMany([ {"Value1": 100, "Value2": 560}, {"Value1": 300, "Value2": 150}, {"Value1": 400, "Value2": ...
Read MoreInsert MongoDB document field only when it's missing?
To insert a MongoDB document field only when it's missing, use the $exists operator in the query condition to target documents where the field doesn't exist, then apply $set to add the field only to those documents. Syntax db.collection.update( { "fieldName": { "$exists": false } }, { "$set": { "fieldName": "value" } }, { "multi": true } ); Sample Data db.missingDocumentDemo.insertMany([ {"StudentFirstName": "Adam", "StudentLastName": "Smith"}, {"StudentFirstName": "Carol", "StudentLastName": "Taylor"}, ...
Read MoreFind all documents that have two specific id's in an array of objects in MongoDB?
To find all documents that have two specific id's in an array of objects in MongoDB, use the $and operator with dot notation to match multiple values within the same array field. Syntax db.collection.find({ $and: [ { "arrayField.property": value1 }, { "arrayField.property": value2 } ] }); Sample Data db.twoSpecificIdsDemo.insertMany([ { PlayerId: 1, ...
Read MoreMongoDB pull with positional operator?
The $pull operator combined with the positional operator ($) in MongoDB allows you to remove specific values from arrays within nested documents. Use $elemMatch to identify the target document and $ to reference the matched array element. Syntax db.collection.update( { "arrayField": { "$elemMatch": { "field": "matchValue" ...
Read MoreSearch a sub-field on MongoDB?
To search a sub-field in MongoDB, use dot notation with the field path enclosed in double quotes. This allows you to query nested fields within embedded documents. Syntax db.collection.find({"parentField.subField": "value"}); Sample Data db.searchSubFieldDemo.insertMany([ { "UserDetails": { "UserEmailId": "John123@gmail.com", "UserAge": 21 } }, ...
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