Redis filters

The following filter types are supported for Redis connections:

Request filters

• JavaScript request filter - Redis: generic request filter that executes arbitrary JavaScript code

• Request logger - Redis: logs requests to stdout, to a file, or to a logger

Response filters

• JavaScript response filter - Redis: generic response filter that executes arbitrary JavaScript code

• Response logger - Redis: logs responses to stdout, to a file, or to a logger

Duplex filters

• JavaScript duplex filter - Redis: generic duplex filter that executes arbitrary JavaScript code for requests and responses

Scripting environment

When a filter is invoked, the following variables will be defined, in addition to the usual JavaScript environment:

• context.packet: the current Redis object request or response, always one of the 5 Redis types. For requests, this is always an Array.

• context.connectionContext.lastRequest: in a response filter, an array containing the request for which this is the response

• context.redisUtil: see below

The context.redisUtil object

This object has the following methods:

• object createObject(string type, object value)

Creates a new Redis object that can be added to or inserted into a request or a response.

The type parameter must be one of the Redis types, namely: "SimpleString", "BulkString", "Error", "Integer", "Array".

The value parameter is used to initialize the value of the object. It should be a string for "SimpleString", "BulkString" and "Error", and a number for "Integer". For "Array", it can be null for an empty array, or a JavaScript array, or a string, or a number.

The same effect can be accomplished with the following methods:

• object createSimpleString(object value)

Creates a new Redis SimpleString from the given object. SimpleString are rarely used.

object createBulkString(object value)

Creates a new Redis BulkString from the given object. BulkStrings are the most common type of strings in Redis.

• object createInteger(object value)

Creates a new Redis Integer from the given object, which should be a number or a string representation of a number. If the number has decimals, it is rounded down.

• object createArray()

• object createArray(object value)

Creates a new Redis Array. If a value is passed in, it is added to the new array, unless it is itself an array, in which case its contents will be added to the new array.

• object createError(object value)

Creates a new Redis Error object with the given value, which should be a string.

• object convertToRedis(object obj)

Converts the given JavaScript object to its Redis equivalent. If obj is:

• null, then null is returned

• a string, then a RedisBulkString is returned

• a number, then a RedisInteger is returned (rounded down if the number has decimals)

• a boolean, then a RedisBulkString is returned with value "true" or "false"

• an object, then a RedisArray is returned in the format of a HashMap for Redis, namely an array with key and value pairs, where the keys are RedisBulkStrings, and the values are converted to Redis objects

• an array, then a RedisArray is returned, containing whatever was in the given array, converted to Redis objects

Examples

Create an array and put it in the current request or response:

let newArray = context.redisUtil.createObject("Array", [789, "Hello"]);

newArray.push("This");

newArray.push(123);

// newArray is now: [789, "Hello", "This", 123]

context.packet[2] = newArray;

Create a complex object:

let response = context.redisUtil.convertToRedis({

name: "Jane Doe",

age: 54,

scores: [78, 96, 32],

address: {

street: "23 Main St",

city: "Oakland",

state: "CA"

}});

This will return the following Redis Array, in which a string is a BulkString, a number is an Integer, and an array is an Array:

["name", "Jane Doe", "age", 54, "score", [78, 96, 32], address, ["street", "23 Main St", "city", "Oakland", "state", "CA"]]