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Increment MongoDB value inside a nested array
To increment a value inside a nested array, use positional operator ($). Let us first create a collection with documents
> db.incrementInNestedArrayDemo.insertOne(
... {
... "StudentId":100,
... "ProjectDetails":
... [
... {"ProjectId":567778888,
... "TeamSize":4
... },
... {
... "ProjectId":67888999,
... "TeamSize":2
... }
... ]
... }
... );
{
"acknowledged" : true,
"insertedId" : ObjectId("5c9a6b7b15e86fd1496b38aa")
}Following is the query to display all documents from a collection with the help of find() method
> db.incrementInNestedArrayDemo.find().pretty();
This will produce the following output
{
"_id" : ObjectId("5c9a6b7b15e86fd1496b38aa"),
"StudentId" : 100,
"ProjectDetails" : [
{
"ProjectId" : 567778888,
"TeamSize" : 4
},
{
"ProjectId" : 67888999,
"TeamSize" : 2
}
]
}Following is the query to increment value inside nested array
> db.incrementInNestedArrayDemo.update({ "StudentId" : 100, "ProjectDetails.ProjectId":67888999} , {$inc:{"ProjectDetails.$.TeamSize":1}});
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })Let us check that the field TeamSize is incremented by 1 or not. Following is the query
> db.incrementInNestedArrayDemo.find().pretty();
This will produce the following output
{
"_id" : ObjectId("5c9a6b7b15e86fd1496b38aa"),
"StudentId" : 100,
"ProjectDetails" : [
{
"ProjectId" : 567778888,
"TeamSize" : 4
},
{
"ProjectId" : 67888999,
"TeamSize" : 3
}
]
}
Updated on: 30-Jul-2019
103 Views
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