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https://github.com/soveran/nest

Generate nested namespaced keys for key-value databases.
https://github.com/soveran/nest

lesscode redis ruby

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Generate nested namespaced keys for key-value databases.

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README 

        
Nest

====



Object Oriented Keys for Redis.



Description

-----------



If you are familiar with databases like [Redis](http://redis.io)

and libraries like [Ohm](http://ohm.keyvalue.org) you already know how

important it is to craft the keys that will hold the data.



```ruby

>> redis = Redic.new

>> redis.call("HSET", "Event:3", "name", "Redis Meetup")

>> redis.call("HGET", "Event:3", "name")

=> ["Redis Meetup"]

```



It is a design pattern in key-value databases to use the key to simulate

structure, and you can read more about this in the [case study for a

Twitter clone](http://redis.io/topics/twitter-clone).



Nest helps you generate those keys by providing chainable namespaces that are

already connected to Redis:



```ruby

>> event = Nest.new("Event")

>> event[3].call("HSET", "name", "Redis Meetup")

>> event[3].call("HGET", "name")

=> ["Redis Meetup"]

```



Alternatively, you can send the Redis commands as messages to Nest,

and if the method definition is missing it will forward the command

to Redis:



```ruby

>> event = Nest.new("Event")

>> event[3].hset("name", "Redis Meetup")

>> event[3].hget("name")

=> ["Redis Meetup"]

```



Usage

-----



To create a new namespace:



```ruby

>> ns = Nest.new("foo")

=> "foo"



>> ns["bar"]

=> "foo:bar"



>> ns["bar"]["baz"]["qux"]

=> "foo:bar:baz:qux"

```



And you can use any object as a key, not only strings:



```ruby

>> ns[:bar][42]

=> "foo:bar:42"

```



In a more realistic tone, lets assume you are working with Redis and

dealing with events:



```ruby

>> event = Nest.new("Event")

=> "Event"



>> id = event[:id].incr

=> 1



>> event[id].hset("name", "Redis Meetup")

=> 1



>> meetup = event[id]

=> "Event:1"



>> meetup.hget("name")

=> ["Redis Meetup"]

```



API

---



`call`: Receives a Redis command and its arguments, and returns the

reply from the Redis server. If the reply from Redis is an error,

an instance of `RuntimeError` is returned.



`call!`: Similar to `call`, but instead of returning

an instance of `RuntimeError` when the command fails, the error is

raised.



`queue`: Receives the same kind of arguments as `call`, but enqueues

the command in a transaction.



`commit`: Commits the transaction and returns the reply from Redis.



Any call to a missing method will result in `Nest` converting the

method name to a Redis command and applying the arguments in an

invocation to `call`.



For example:



```ruby

ns = Nest.new("foo")

ns.append("hello,")

ns.append(" world")

ns.get

```



Is equivalent to:



```ruby

ns = Nest.new("foo")

ns.call("APPEND", "hello,")

ns.call("APPEND", " world")

ns.call("GET")

```



Supplying your existing Redis instance

--------------------------------------



You can supply a [Redic](https://github.com/amakawa/redic) instance as

a second parameter. If you don't, a default instance is created for you:



```ruby

>> redis = Redic.new("redis://localhost:6379")

=> #



>> event = Nest.new("Event", redis)

=> "Event"



>> event[:id].call("TYPE")

=> "string"

```



`Nest` objects respond to `redis` and return a `Redic` instance. It is

automatically reused when you create a new namespace, and you can reuse it when

creating a new instance of Nest:



```ruby

>> event = Nest.new("Event", meetup.redis)

=> "Event"

```



Nest allows you to execute all the Redis commands that expect a key as the

first parameter. If you use any other command, the result can be unexpected.



Differences with redis-namespace

--------------------------------



[redis-namespace](http://github.com/defunkt/redis-namespace) wraps Redis

and translates the keys back and forth transparently.



Use redis-namespace when you want all your application keys to live in a

different scope.



Use Nest when you want to use the keys to represent structure.



Tip: instead of using redis-namespace, it is recommended that you run a

different instance of `redis-server`. Translating keys back and forth is not

only delicate, but unnecessary and counterproductive.



Differences with Ohm

--------------------



[Ohm](http://ohm.keyvalue.org) lets you map Ruby objects to Redis with

little effort. It not only alleviates you from the pain of generating

keys for each object, but also helps you when dealing with references

between objects.



Use Ohm when you want to use Redis as your database.



Use Nest when mapping objects with Ohm is not possible or overkill.



Tip: Ohm uses Nest internally to deal with keys. Having a good knowledge

of Nest will let you extend Ohm to suit your needs.



Installation

------------



```

$ gem install nest

```