How to update array inside object in mongodb?

@dalton_moen 

To update an array inside an object in MongoDB, you can use the $set operator along with the $ operator to specify the element of the array that you want to update.

For example, let's say you have a collection called students with the following documents:

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{
  _id: 1,
  name: "John",
  grades: [80, 90, 95]
},
{
  _id: 2,
  name: "Jane",
  grades: [70, 85, 90]
}

To update the second grade of the student with _id 1, you can use the following update operation:

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db.students.updateOne(
   { _id: 1 },
   { $set: { "grades.1": 87 } }
)

This will update the second element (index 1) of the grades array to 87 for the student with _id 1.

You can also use the $ operator to update multiple elements of an array at once. For example, to update the first and third grades of the student with _id 1, you can use the following update operation:

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db.students.updateOne(
   { _id: 1 },
   { $set: { "grades.$[i]": 87 } },
   { arrayFilters: [ { "i": { $in: [0, 2] } } ] }
)

This will update the first and third elements (index 0 and 2) of the grades array to 87 for the student with _id 1.

Note that you can also use the updateMany() method to update multiple documents at once.

I hope this helps! Let me know if you have any questions.