Command: STR.RANGE

Overview

The STR.RANGE command returns a substring from a string value stored at a specified key, based on start and end offsets (inclusive). It supports negative indices, enabling easy access to characters counted from the end of the string.

Command Name

STR.RANGE

Description

Fetches a substring from the string value at the given key. The command uses inclusive index ranges, with support for both positive and negative indexing.

  • start and end specify the beginning and end of the substring (inclusive of start , exclusive of end + 1 ).

  • Negative offsets count from the end of the string ( -1 is the last character, -2 the second last, etc.).

Use Cases

  • Extracting a snippet from a large text or paragraph.
  • Reusing substrings for further operations like STR.SET , STR.APPEND .
  • Testing or validating specific parts of a stored string value.
  • Implementing document-based or line-based inspection (e.g., logs, texts).

Syntax 

  STR.RANGE <key> <start> <end>

  • <key> : The string key from which to extract the substring.

  • <start> : Starting offset (can be negative).

  • <end> : Ending offset (can be negative).

Permissions

  • Requires read access to the key.

  • No modification is performed; safe for concurrent reads.

Input Examples

Basic positive offsets 
  localhost:9219> SET myKey "There are many variations of passages"

Ok

localhost:9219> STR.RANGE myKey 0 4

Ok "There"
Mixed positive and negative offsets 
  localhost:9219> STR.RANGE myKey 15 -1

Ok "variations of passages"
Negative start index 
  localhost:9219> STR.RANGE myKey -8 4

Ok "pass"
Start > End 
  localhost:9219> STR.RANGE myKey 15 10

Ok "variations"

Output Examples

Input Command Output
STR.RANGE myKey 0 5 "There "
STR.RANGE myKey 15 10 "variations"
STR.RANGE myKey -8 4 "pass"
STR.RANGE myKey 15 -1 "variations of passages"

Behavior on Error

Condition Error Message
Missing arguments InvalidKeyError: invalid number of arguments
Key does not exist KeyNotFoundError: provided key does not exist
Key exists but is not a string InvalidValueError: the existing value for the provided key must be a string
Non-integer start/end InvalidArgsError: start offsets must be valid integers