Module: Redis::Commands::Lists

Included in:
Redis::Commands
Defined in:
lib/redis/commands/lists.rb

Instance Method Summary collapse

Instance Method Details

#blmove(source, destination, where_source, where_destination, timeout: 0) ⇒ nil, String

Remove the first/last element in a list and append/prepend it to another list and return it, or block until one is available.

Examples:

With timeout

element = redis.blmove("foo", "bar", "LEFT", "RIGHT", timeout: 5)
  # => nil on timeout
  # => "element" on success

Without timeout

element = redis.blmove("foo", "bar", "LEFT", "RIGHT")
  # => "element"

Parameters:

  • source (String)

    source key

  • destination (String)

    destination key

  • where_source (String, Symbol)

    from where to remove the element from the source list e.g. 'LEFT' - from head, 'RIGHT' - from tail

  • where_destination (String, Symbol)

    where to push the element to the source list e.g. 'LEFT' - to head, 'RIGHT' - to tail

  • options (Hash)
    • :timeout => Numeric: timeout in seconds, defaults to no timeout

Returns:

  • (nil, String)

    the element, or nil when the source key does not exist or the timeout expired


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# File 'lib/redis/commands/lists.rb', line 55

def blmove(source, destination, where_source, where_destination, timeout: 0)
  where_source, where_destination = _normalize_move_wheres(where_source, where_destination)

  command = [:blmove, source, destination, where_source, where_destination, timeout]
  send_blocking_command(command, timeout)
end

#blpop(*args) ⇒ nil, [String, String]

Remove and get the first element in a list, or block until one is available.

Examples:

With timeout

list, element = redis.blpop("list", :timeout => 5)
  # => nil on timeout
  # => ["list", "element"] on success

Without timeout

list, element = redis.blpop("list")
  # => ["list", "element"]

Blocking pop on multiple lists

list, element = redis.blpop(["list", "another_list"])
  # => ["list", "element"]

Parameters:

  • keys (String, Array<String>)

    one or more keys to perform the blocking pop on

  • options (Hash)
    • :timeout => Integer: timeout in seconds, defaults to no timeout

Returns:

  • (nil, [String, String])
    • nil when the operation timed out
    • tuple of the list that was popped from and element was popped otherwise

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# File 'lib/redis/commands/lists.rb', line 150

def blpop(*args)
  _bpop(:blpop, args)
end

#brpop(*args) ⇒ nil, [String, String]

Remove and get the last element in a list, or block until one is available.

Parameters:

  • keys (String, Array<String>)

    one or more keys to perform the blocking pop on

  • options (Hash)
    • :timeout => Integer: timeout in seconds, defaults to no timeout

Returns:

  • (nil, [String, String])
    • nil when the operation timed out
    • tuple of the list that was popped from and element was popped otherwise

See Also:


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# File 'lib/redis/commands/lists.rb', line 166

def brpop(*args)
  _bpop(:brpop, args)
end

#brpoplpush(source, destination, deprecated_timeout = 0, timeout: deprecated_timeout) ⇒ nil, String

Pop a value from a list, push it to another list and return it; or block until one is available.

Parameters:

  • source (String)

    source key

  • destination (String)

    destination key

  • options (Hash)
    • :timeout => Integer: timeout in seconds, defaults to no timeout

Returns:

  • (nil, String)
    • nil when the operation timed out
    • the element was popped and pushed otherwise

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# File 'lib/redis/commands/lists.rb', line 181

def brpoplpush(source, destination, deprecated_timeout = 0, timeout: deprecated_timeout)
  command = [:brpoplpush, source, destination, timeout]
  send_blocking_command(command, timeout)
end

#lindex(key, index) ⇒ String

Get an element from a list by its index.

Parameters:

  • key (String)
  • index (Integer)

Returns:

  • (String)

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# File 'lib/redis/commands/lists.rb', line 191

def lindex(key, index)
  send_command([:lindex, key, index])
end

#linsert(key, where, pivot, value) ⇒ Integer

Insert an element before or after another element in a list.

Parameters:

  • key (String)
  • where (String, Symbol)

    BEFORE or AFTER

  • pivot (String)

    reference element

  • value (String)

Returns:

  • (Integer)

    length of the list after the insert operation, or -1 when the element pivot was not found


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# File 'lib/redis/commands/lists.rb', line 203

def linsert(key, where, pivot, value)
  send_command([:linsert, key, where, pivot, value])
end

#llen(key) ⇒ Integer

Get the length of a list.

Parameters:

  • key (String)

Returns:

  • (Integer)

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# File 'lib/redis/commands/lists.rb', line 10

def llen(key)
  send_command([:llen, key])
end

#lmove(source, destination, where_source, where_destination) ⇒ nil, String

Note:

This command comes in place of the now deprecated RPOPLPUSH. Doing LMOVE RIGHT LEFT is equivalent.

Remove the first/last element in a list, append/prepend it to another list and return it.

Parameters:

  • source (String)

    source key

  • destination (String)

    destination key

  • where_source (String, Symbol)

    from where to remove the element from the source list e.g. 'LEFT' - from head, 'RIGHT' - from tail

  • where_destination (String, Symbol)

    where to push the element to the source list e.g. 'LEFT' - to head, 'RIGHT' - to tail

Returns:

  • (nil, String)

    the element, or nil when the source key does not exist


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# File 'lib/redis/commands/lists.rb', line 27

def lmove(source, destination, where_source, where_destination)
  where_source, where_destination = _normalize_move_wheres(where_source, where_destination)

  send_command([:lmove, source, destination, where_source, where_destination])
end

#lpop(key, count = nil) ⇒ String+

Remove and get the first elements in a list.

Parameters:

  • key (String)
  • count (Integer) (defaults to: nil)

    number of elements to remove

Returns:

  • (String, Array<String>)

    the values of the first elements


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# File 'lib/redis/commands/lists.rb', line 103

def lpop(key, count = nil)
  command = [:lpop, key]
  command << count if count
  send_command(command)
end

#lpush(key, value) ⇒ Integer

Prepend one or more values to a list, creating the list if it doesn't exist

Parameters:

  • key (String)
  • value (String, Array<String>)

    string value, or array of string values to push

Returns:

  • (Integer)

    the length of the list after the push operation


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# File 'lib/redis/commands/lists.rb', line 67

def lpush(key, value)
  send_command([:lpush, key, value])
end

#lpushx(key, value) ⇒ Integer

Prepend a value to a list, only if the list exists.

Parameters:

  • key (String)
  • value (String)

Returns:

  • (Integer)

    the length of the list after the push operation


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# File 'lib/redis/commands/lists.rb', line 76

def lpushx(key, value)
  send_command([:lpushx, key, value])
end

#lrange(key, start, stop) ⇒ Array<String>

Get a range of elements from a list.

Parameters:

  • key (String)
  • start (Integer)

    start index

  • stop (Integer)

    stop index

Returns:

  • (Array<String>)

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# File 'lib/redis/commands/lists.rb', line 213

def lrange(key, start, stop)
  send_command([:lrange, key, start, stop])
end

#lrem(key, count, value) ⇒ Integer

Remove elements from a list.

Parameters:

  • key (String)
  • count (Integer)

    number of elements to remove. Use a positive value to remove the first count occurrences of value. A negative value to remove the last count occurrences of value. Or zero, to remove all occurrences of value from the list.

  • value (String)

Returns:

  • (Integer)

    the number of removed elements


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# File 'lib/redis/commands/lists.rb', line 226

def lrem(key, count, value)
  send_command([:lrem, key, count, value])
end

#lset(key, index, value) ⇒ String

Set the value of an element in a list by its index.

Parameters:

  • key (String)
  • index (Integer)
  • value (String)

Returns:

  • (String)

    OK


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# File 'lib/redis/commands/lists.rb', line 236

def lset(key, index, value)
  send_command([:lset, key, index, value])
end

#ltrim(key, start, stop) ⇒ String

Trim a list to the specified range.

Parameters:

  • key (String)
  • start (Integer)

    start index

  • stop (Integer)

    stop index

Returns:

  • (String)

    OK


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# File 'lib/redis/commands/lists.rb', line 246

def ltrim(key, start, stop)
  send_command([:ltrim, key, start, stop])
end

#rpop(key, count = nil) ⇒ String+

Remove and get the last elements in a list.

Parameters:

  • key (String)
  • count (Integer) (defaults to: nil)

    number of elements to remove

Returns:

  • (String, Array<String>)

    the values of the last elements


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# File 'lib/redis/commands/lists.rb', line 114

def rpop(key, count = nil)
  command = [:rpop, key]
  command << count if count
  send_command(command)
end

#rpoplpush(source, destination) ⇒ nil, String

Remove the last element in a list, append it to another list and return it.

Parameters:

  • source (String)

    source key

  • destination (String)

    destination key

Returns:

  • (nil, String)

    the element, or nil when the source key does not exist


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# File 'lib/redis/commands/lists.rb', line 125

def rpoplpush(source, destination)
  send_command([:rpoplpush, source, destination])
end

#rpush(key, value) ⇒ Integer

Append one or more values to a list, creating the list if it doesn't exist

Parameters:

  • key (String)
  • value (String, Array<String>)

    string value, or array of string values to push

Returns:

  • (Integer)

    the length of the list after the push operation


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# File 'lib/redis/commands/lists.rb', line 85

def rpush(key, value)
  send_command([:rpush, key, value])
end

#rpushx(key, value) ⇒ Integer

Append a value to a list, only if the list exists.

Parameters:

  • key (String)
  • value (String)

Returns:

  • (Integer)

    the length of the list after the push operation


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# File 'lib/redis/commands/lists.rb', line 94

def rpushx(key, value)
  send_command([:rpushx, key, value])
end