struct Redis::JSON(Runnable)

Overview

Redis::JSON wraps a Redis::Client or Redis::Cluster to execute commands against keys storing JSON data using the RedisJSON plugin for Redis.

require "redis"
require "redis/json"
require "uuid/json"

struct Person
  include JSON::Serializable

  getter id : UUID
  getter name : String
  getter email : String

  def initialize(@id, @name, @email)
  end
end

redis = Redis::Client.new

id = UUID.random

redis.json.set "person:#{id}", ".", Person.new(id, "Jamie", "[email protected]")
redis.json.get("person:#{id}", ".", as: Person)
# => Person(@email="[email protected]", @id=UUID(081af617-6b50-48d3-b53f-dbc17a1072f5), @name="Jamie")
redis.json.get("person:#{id}", ".name", as: String)
# => "Jamie"

Defined in:

json.cr

Constructors

Instance Method Summary

Constructor Detail

def self.new(redis : Runnable) #

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Instance Method Detail

def arrappend(key : String, path : String, value) #

Append value as JSON to the array located at the JSONPath in key

redis.json.arrappend "posts:#{id}", ".tags", "redis"

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def arrappend(key : String, path : String, *, values : Array) #

Append values as JSON to the array located at the JSONPath in key

redis.json.arrappend "posts:#{id}", ".tags", %w[redis crystal]

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def arrindex(key : String, path : String, value, between range : Range(Int, Int | Nil)) #

Get the index of value in the array located at the JSONPath in key if and only if it falls in the specified range

redis.json.arrindex "posts:#{id}", ".tags", "redis", between: 1..3
# => 2

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def arrindex(key : String, path : String, value) #

Get the index of value in the array located at the JSONPath in key

redis.json.arrindex "posts:#{id}", ".tags", "redis" # => 2

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def arrinsert(key : String, path : String, index : Int, value) #

Insert value into the array located at the JSONPath in key at index

redis.json.arrinsert "posts:#{id}", ".tags", index: 1, value: "redis"
# => 3

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def arrinsert(key : String, path : String, index : Int, *, values : Array) #

Insert the elements of values into the array located at the JSONPath in key at index

redis.json.arrinsert "posts:#{id}", ".tags", index: 1, values: %w[
  redis
  crystal
]
# => 4

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def arrlen(key : String, path : String) #

Get the number of elements in the array located at the JSONPath in key

redis.json.arrlen "posts:#{id}", ".tags"
# => 4

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def arrpop(key : String, path : String | Nil = nil, *, index : Int = -1) #

Remove and return the value located at index (defaulting to the last element) in the array located at the JSONPath in key

redis.json.arrlen "posts:#{id}", ".tags"
# => 4

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def arrpop(key : String, path : String, *, index : Int = -1, as : T.class) : T | Nil forall T #

Remove and return the value located at index (defaulting to the last element) in the array located at the JSONPath in key

redis.json.arrlen "posts:#{id}", ".tags"
# => 4

NOTE This method cannot be invoked on a pipeline or the transaction yielded to a Redis::Connection#multi block.


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def clear(key : String, path : String | Nil = nil) #

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def del(key : String, path : String | Nil = nil) #

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def get(key : String, path : String, as type : T.class) : T | Nil forall T #

Get the value stored at the given JSONPath inside the given key, deserializing the value into the type T. You can use this to deserialize your custom JSON::Serializable objects.

struct Order
  include JSON::Serializable
  getter id : UUID
  getter customer_id : UUID
  getter line_items : Array(LineItem)
end

struct LineItem
  include JSON::Serializable
  getter product_id : UUID
  getter quantity : Int32
  getter unit_price_cents : Int32
end

# Get the Order at the root
redis.json.get("order:#{id}", ".", as: Order)
# Get the LineItems at the `.line_items` JSONPath
# Note the `$` at the beginning to make it an array
redis.json.get("order:#{id}", "$.line_items", as: Array(LineItem))
# Get only the `product_id` properties of all the `line_items`
redis.json.get("order:#{id}", "$.line_items..product_id", as: Array(UUID))

NOTE This method cannot be used in a pipeline or Redis::Connection#multi block because it operates on the value returned from the Redis server inside the method, which isn't possible when using pipelines or multi.


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def get(key : String, path : String) #

Get the raw JSON string representation at the given key nested at the given JSONPath.

email = redis.json.get("user:#{id}", ".email").as(String)
# => "[email protected]"

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def get(key : String, paths : Array(String), as type : T.class = ::JSON::Any) forall T #

Get the values stored at the specifed JSONPaths, deserializing them into the specified type as values in a Hash.

if result = redis.json.get("posts:#{id}", %w[title tags], as: String | Array(String))
  result         # => {"title" => "JSON with Redis", tags: ["redis", "json", "crystal"]}
  typeof(result) # => Hash(String, String | Array(String))
end

NOTE This method cannot be used in a pipeline or Redis::Connection#multi block because it operates on the value returned from the Redis server, which isn't a thing when using pipelines or multi.


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def get(key : String) #

Get the raw JSON string at the specified key


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def mget(keys : Array(String), path : String, as type : T.class) : Array(T | Nil) forall T #

Get the values for all keys at the specified JSONPaths.

NOTE This method cannot be used in a pipeline or Redis::Connection#multi block because it operates on the value returned from the Redis server inside the method, which isn't possible when using pipelines or multi.

NOTE If you are using a cluster, the keys must all be on the same shard, or you may only get some of them back with this method. When using #mget in a cluster, you'll most likely want to use subhashed keys (with {} around the same part of the name) to ensure all keys are on the same shard.


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def numincrby(key : String, path : String, count : String | Int, as type : T.class) : T forall T #

Increment the number at the specified JSONPath

redis.json.numincrby "product:#{id}", ".purchase_count", 1, as: Int64
# => 2

If key exists and an incrementable number exists at the specified JSONPath (including the possibility of incrementing multiple numbers if the JSONPath resolves to multiple numeric values), then this method returns a value of type T. If the JSONPath resolves to multiple values (for example, it begins with "$" or is recursive), you will need to specify that it can be an Array of that type.

NOTE This method cannot be used on deferred command runners like Redis::Pipeline or Redis::Transaction. It eagerly consumes the result from the server, so the result must not be deferred.


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def numincrby(key : String, path : String, count : String | Int) #

Increment the number at the specified JSONPath

redis.json.numincrby "product:#{id}", ".purchase_count", 1

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def set(key : String, path : String, value, *, nx = false, xx = false) #

Set the given key to the given JSON value. The value will have to_json called on it automatically. The nx and xx arguments are identical to Redis::Commands#set.

Store a user at the root JSONPath (.) of the specified key:

struct User
  include JSON::Serializable

  getter id : UUID
  getter name : String
  getter email : String
end

redis.json.set "user:#{user.id}", ".", user

Update (with xx so we ensure the key exists) a user's email by setting the new email value at the .email JSONPath:

redis.json.set "user:#{id}", ".email", new_email, xx: true

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def toggle(key : String, path : String) #

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