可选awaitIf awaitData is set to true, when the cursor reaches the end of the capped collection, MongoDB blocks the query thread for a period of time waiting for new data to arrive. When new data is inserted into the capped collection, the blocked thread is signaled to wake up and return the next batch to the client.
可选batchSpecifies the number of documents to return in each response from MongoDB
可选bsonreturn BSON regular expressions as BSONRegExp instances.
可选checkthe serializer will check if keys are valid.
可选commentComment to apply to the operation.
In server versions pre-4.4, 'comment' must be string. A server error will be thrown if any other type is provided.
In server versions 4.4 and above, 'comment' can be any valid BSON type.
可选enableEnable utf8 validation when deserializing BSON documents. Defaults to true.
可选fieldsallow to specify if there what fields we wish to return as unserialized raw buffer.
可选ignoreserialize will not emit undefined fields (default:true)
可选maxWhen applicable maxAwaitTimeMS controls the amount of time subsequent getMores
that a cursor uses to fetch more data should take. (ex. cursor.next())
可选maxWhen applicable maxTimeMS controls the amount of time the initial command
that constructs a cursor should take. (ex. find, aggregate, listCollections)
可选no可选promotewhen deserializing a Binary will return it as a node.js Buffer instance.
可选promotewhen deserializing a Long will fit it into a Number if it's smaller than 53 bits.
可选promotewhen deserializing will promote BSON values to their Node.js closest equivalent types.
可选rawEnabling the raw option will return a Node.js Buffer which is allocated using allocUnsafe API. See this section from the Node.js Docs here for more detail about what "unsafe" refers to in this context. If you need to maintain your own editable clone of the bytes returned for an extended life time of the process, it is recommended you allocate your own buffer and clone the contents:
const raw = await collection.findOne({}, { raw: true });
const myBuffer = Buffer.alloc(raw.byteLength);
myBuffer.set(raw, 0);
// Only save and use `myBuffer` beyond this point
Please note there is a known limitation where this option cannot be used at the MongoClient level (see NODE-3946).
It does correctly work at Db, Collection, and per operation the same as other BSON options work.
可选read可选read可选serializeserialize the javascript functions (default:false).
可选session可选tailableBy default, MongoDB will automatically close a cursor when the client has exhausted all results in the cursor. However, for capped collections you may use a Tailable Cursor that remains open after the client exhausts the results in the initial cursor.
可选usewhen deserializing a Long will return as a BigInt.
BSON Serialization options.