`module Hashes`

Methods for managing Redis hashes.

Definitions

`def hlen(key)`

Get the number of fields in a hash. O(1). See https://redis.io/commands/hlen for more details.

Signature

parameter　key　Key
returns　Integer

Implementation

def hlen(key)
	call("HLEN", key)
end

`def hset(key, field, value)`

Set the string value of a hash field. O(1) for each field/value pair added, so O(N) to add N field/value pairs when the command is called with multiple field/value pairs. See https://redis.io/commands/hset for more details.

Signature

parameter　key　Key
returns　Integer: if new field added returns "1" otherwise "0"

Implementation

def hset(key, field, value)
	call("HSET", key, field, value)
end

`def hsetnx(key, field, value)`

Set the value of a hash field, only if the field does not exist. O(1). See https://redis.io/commands/hsetnx for more details.

Signature

parameter　key　Key
parameter　field　String
parameter　value　String
returns　Boolean: "true" if new field added, "false" otherwise

Implementation

def hsetnx(key, field, value)
	call("HSETNX", key, field, value) > 0
end

`def hmset(key, *attrs)`

Set multiple hash fields to multiple values. O(N) where N is the number of fields being set. See https://redis.io/commands/hmset for more details.

Signature

parameter　key　Key
returns　String: default: "OK"

Implementation

def hmset(key, *attrs)
	call("HMSET", key, *attrs)
end

`def mapped_hmset(key, hash)`

Set multiple hash fields to multiple values, by providing a hash

redis.mapped_hmset("hash", "f1" => "v1", "f2" => "v2" ) # => "OK"

See <#hmset> for more details.

Signature

parameter　key　Key
parameter　hash　Hash: a non-empty hash with fields mapping to values
returns　String: default: "OK"

Implementation

def mapped_hmset(key, hash)
	hmset(key, *hash.flatten)
end

`def hget(key, field)`

Get the value of a hash field. O(1). See https://redis.io/commands/hget for more details.

Signature

parameter　key　Key
parameter　field　String
returns　String, Null

Implementation

def hget(key, field)
	call("HGET", key, field)
end

`def hmget(key, *fields)`

Get the values of all the given hash fields. O(N) where N is the number of fields being requested. See https://redis.io/commands/hmget for more details.

Signature

parameter　key　Key
parameter　fields　Array(String): array of fields
returns　Array

Implementation

def hmget(key, *fields)
	call("HMGET", key, *fields)
end

`def mapped_hmget(key, *fields)`

Get the values of all the given hash fields and return as array

redis.mapped_hmget("hash", "f1", "f2") # => "f1" => "v1", "f2" => "v2"

See <#hmget> for more details.

Signature

parameter　key　Key
parameter　fields　Array(String): array of fields
returns　Hash: a hash mapping the specified fields to their values

Implementation

def mapped_hmget(key, *fields)
	reply = hmget(key, *fields)
	Hash[fields.zip(reply)]
end

`def hdel(key, *fields)`

Delete one or more hash fields. O(N) where N is the number of fields to be removed. See https://redis.io/commands/hdel for more details.

Signature

parameter　key　Key
parameter　field　String
returns　Integer: number of deleted fields

Implementation

def hdel(key, *fields)
	call("HDEL", key, *fields)
end

`def hexists(key, field)`

Determine if a hash field exists. O(1). See https://redis.io/commands/hexists for more details.

Signature

parameter　key　Key
parameter　field　String
returns　Boolean

Implementation

def hexists(key, field)
	call("HEXISTS", key, field) > 0
end

`def hincrby(key, field, increment)`

Increment the integer value of a hash field by the given number. O(1). See https://redis.io/commands/hincrby for more details.

Signature

parameter　key　Key
parameter　field　String
parameter　increment　Integer
returns　Integer: field value after increment

Implementation

def hincrby(key, field, increment)
	call("HINCRBY", key, field, increment)
end

`def hincrbyfloat(key, field, increment)`

Increment the float value of a hash field by the given amount. O(1). See https://redis.io/commands/hincrbyfloat for more details.

Signature

parameter　key　Key
parameter　field　String
parameter　increment　Double
returns　Float: field value after increment

Implementation

def hincrbyfloat(key, field, increment)
	Float(call("HINCRBYFLOAT", key, field, increment))
end

`def hkeys(key)`

Get all the fields in a hash. O(N) where N is the size of the hash. See https://redis.io/commands/hkeys for more details.

Signature

parameter　key　Key
returns　Array

Implementation

def hkeys(key)
	call("HKEYS", key)
end

`def hvals(key)`

Get all the values in a hash. O(N) where N is the size of the hash. See https://redis.io/commands/hvals for more details.

Signature

parameter　key　Key
returns　Array

Implementation

def hvals(key)
	call("HVALS", key)
end

`def hgetall(key)`

Get all the fields and values in a hash. O(N) where N is the size of the hash. See https://redis.io/commands/hgetall for more details.

Signature

parameter　key　Key
returns　Hash

Implementation

def hgetall(key)
	call("HGETALL", key).each_slice(2).to_h
end

`def hscan(key, cursor = "0", match: nil, count: nil)`

Iterates fields of Hash types and their associated values. O(1) for every call. O(N) for a complete iteration, including enough command calls for the cursor to return back to 0. N is the number of elements inside the collection. See https://redis.io/commands/hscan/ for more details.

Signature

parameter　cursor　Cursor
returns　Hash

Implementation

def hscan(key, cursor = "0", match: nil, count: nil)
	arguments = [key, cursor]
	
	if match
		arguments.append("MATCH", match)
	end
	
	if count
		arguments.append("COUNT", count)
	end
	
	call("HSCAN", *arguments)
end

`def hscan_each(key, cursor = "0", match: nil, count: nil, &block)`

Iterate over each field and the value of the hash, using HSCAN.

Implementation

def hscan_each(key, cursor = "0", match: nil, count: nil, &block)
	return enum_for(:hscan_each, key, cursor, match: match, count: count) unless block_given?
	
	while true
		cursor, data = hscan(key, cursor, match: match, count: count)
		
		data.each_slice(2, &block)
		
		break if cursor == "0"
	end
end