{"id":169010,"date":"2023-10-05T09:23:40","date_gmt":"2023-10-05T09:23:40","guid":{"rendered":"https:\/\/namso-gen.co\/blog\/how-to-find-a-common-value-in-an-array-in-mongodb\/"},"modified":"2023-10-05T09:23:40","modified_gmt":"2023-10-05T09:23:40","slug":"how-to-find-a-common-value-in-an-array-in-mongodb","status":"publish","type":"post","link":"https:\/\/namso-gen.co\/blog\/how-to-find-a-common-value-in-an-array-in-mongodb\/","title":{"rendered":"How to find a common value in an array in MongoDB?"},"content":{"rendered":"

In MongoDB, finding a common value in an array involves using the aggregation framework and the $group operator. The $group operator groups documents in a collection by a specified expression, and in this case, we can group by the array field and use the $push operator to create an array of all values. Once we have an array of all values, we can then find the common value using the $setIntersection operator.<\/p>\n

Here is the MongoDB aggregation query to find a common value in an array:<\/b><\/p>\n

“`
\ndb.collection.aggregate([
\n { $unwind: “$arrayField” },
\n {
\n $group: {
\n _id: null,
\n commonValues: { $push: “$arrayField” }
\n }
\n },
\n {
\n $project: {
\n commonValue: {
\n $setIntersection: [“$commonValues”]
\n }
\n }
\n }
\n])
\n“`<\/p>\n

This query first unwinds the array field, groups all values from the array into a single array, and then using the $setIntersection operator, finds the common value.<\/p>\n

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