Filter mongodb data via API requests - mongodb

Question

I am trying to figure out how to filter data in mongodb Atlas via API requests.
My json structure:
{
_id: ObjectId,
level: number,
names: Array
}
I learned how to filter by _id. I pass the id via url, and fetch data with filter parameter using $oid in the body.
But the question is: how to filter data by level and get the list of data assign to certain level? I don't know what to use instead of $oid 🤷🏻‍♂️ If I just change the id/_id to level I don't receive anything.
const {
query: { id },
method,
} = req
....
const readData = await fetch(`${baseUrl}/find`, {
...fetchOptions,
body: JSON.stringify({
...fetchBody,
filter: { _id: { $oid: id } },
}),
})

Answer 1

The difference here has to do with data types. Your current query, which works when filtering on _id is:
{ _id: { $oid: id } }
The $oid component of this query is related to the fact that you are using the (default) ObjectId type for that field. $oid itself is the extended JSON representation of that data type. Other languages and interfaces have different ways of representing or constructing ObjectIds.
You have a different data type for your level field - a number. So attempting to do a similar query on that field such as:
{ level: { $oid: <value>} }
Will either result in the query failing (if the ObjectId is unable to be created from <value> due to its specific structure) or in no documents being returned (since no documents have ObjectIds for this field).
Removing the wrapping $oid should solve the problem:
{ level: <value> }