Request filters - MySQL

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.

Context

All request filters define the following variables, which can be accessed from your JavaScript code:

• 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()

  • result: an object used to indicate to Gallium Data what to do with the packet

  • filterContext : variables available to all invocations of this filter

  • connectionContext : variables that persist through the life of this database connection

  • projectContext: variables available to all filters in the project

See the Contexts page for more information about the various context objects.

Request filters types

• JavaScript request filter: can be invoked for any request packets

• Query filter: invoked for SQL queries

• Request logger : logs some or all client requests

• Query logger: logs some or all queries