Request Filters - MongoDB
Request filters are filters that are invoked when a request is received from the database client. Request filters are given the opportunity to look at the request and do whatever they want with it: let it through, modify it, or reject it.
Request filters can potentially be called for every single type of request, such as authentication, close result set, and so on, but they are usually most useful for command requests.
A typical example is a query filter, which is called whenever a database query is received from the client. Query filters are given a chance to look at the request and do with it as they please.
log : A Logger object to output messages to the logging system
context : a container object with the following properties:
packet : the packet being processed
packetType : the type of the packet, equivalent to context.packet.getPacketType()
filterContext : the variables that persist through the life of the filter
adapterContext : the variables that persist through the life of this database connection
Request filters for MongoDB
Query request filter: invoked for packets of type QUERY, can be filtered by the content of the query document
Message request filter: invoked for request packets of type MSG, can be filtered by the contents of the document