JSON Commands

JSON.SET-&-JSON.GET

RedisJSON stores JSON documents natively. Query nested paths, update individual fields, and manipulate arrays without fetching the entire document.

You'll Learn

  • Storing JSON with JSON.SET
  • Querying paths with JSON.GET
  • Updating nested fields
  • Array and object manipulation
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1. What Is RedisJSON?

Normally, Redis stores JSON as a string - you GET the whole thing, parse it, modify it, and SET it back. RedisJSON (a Redis module) understands JSON structure and lets you operate on parts of it directly.

Without RedisJSON

  • GET → Parse → Modify → Stringify → SET
  • Always transfer entire document
  • Race conditions on concurrent updates

With RedisJSON

  • Update specific path atomically
  • Transfer only what you need
  • Native array/object operations

Availability

RedisJSON requires the Redis Stack or the RedisJSON module. It's not part of core Redis. Check with MODULE LIST to see if it's loaded. Cloud providers like Redis Cloud and some managed services include it.

2. JSON.SET: Store Documents

JSON.SET stores a JSON value at a key and path. The root path is $ (or . for legacy syntax).

Basic JSON.SET

# Store a document at root
JSON.SET user:1001 $ '{"name":"John","email":"john@example.com","age":30}'
OK

# Retrieve it
JSON.GET user:1001
"{\"name\":\"John\",\"email\":\"john@example.com\",\"age\":30}"

# Pretty print
JSON.GET user:1001 INDENT "  " NEWLINE "\n"
{
  "name": "John",
  "email": "john@example.com",
  "age": 30
}

SET Options

# Only set if key doesn't exist (NX)
JSON.SET user:1002 $ '{"name":"Jane"}' NX
OK  # or (nil) if exists

# Only set if key exists (XX)
JSON.SET user:1001 $ '{"name":"John Updated"}' XX
OK  # or (nil) if doesn't exist

3. JSON.GET: Query Paths

Use JSONPath expressions to retrieve specific parts of a document without fetching everything.

Path Queries

# Get specific field
JSON.GET user:1001 $.name
"[\"John\"]"

# Get multiple fields
JSON.GET user:1001 $.name $.email
"{\"$.name\":[\"John\"],\"$.email\":[\"john@example.com\"]}"

# Nested paths
JSON.SET user:1001 $ '{"profile":{"settings":{"theme":"dark"}}}'
JSON.GET user:1001 $.profile.settings.theme
"[\"dark\"]"

# Array access
JSON.SET user:1001 $ '{"tags":["admin","vip","active"]}'
JSON.GET user:1001 $.tags[0]
"[\"admin\"]"
JSON.GET user:1001 $.tags[-1]
"[\"active\"]"

JSONPath Syntax

  • $ - Root of document
  • $.field - Object field
  • $.arr[0] - Array index (0-based)
  • $.arr[-1] - Last element
  • $.arr[*] - All elements
  • $..field - Recursive descent

4. Updating Documents

Update specific fields without touching the rest of the document.

Field Updates

# Update a single field
JSON.SET user:1001 $.email '"newemail@example.com"'
OK

# Add a new field
JSON.SET user:1001 $.verified 'true'
OK

# Update nested field
JSON.SET user:1001 $.profile.settings.theme '"light"'
OK

# Delete a field
JSON.DEL user:1001 $.temporary_field
(integer) 1

Numeric Operations

# Increment number
JSON.SET user:1001 $.points '100'
JSON.NUMINCRBY user:1001 $.points 10
"110"

# Multiply
JSON.NUMMULTBY user:1001 $.points 2
"220"

# Works on nested paths too
JSON.NUMINCRBY user:1001 $.stats.loginCount 1

5. Array Operations

RedisJSON has dedicated commands for array manipulation - append, insert, pop, trim.

Array Commands

# Setup
JSON.SET user:1001 $ '{"tags":["user"]}'

# Append to array
JSON.ARRAPPEND user:1001 $.tags '"vip"' '"premium"'
(integer) 3  # New length

# Insert at position
JSON.ARRINSERT user:1001 $.tags 1 '"early-adopter"'
(integer) 4  # ["user","early-adopter","vip","premium"]

# Get array length
JSON.ARRLEN user:1001 $.tags
(integer) 4

# Pop last element
JSON.ARRPOP user:1001 $.tags
"\"premium\""

# Pop from index
JSON.ARRPOP user:1001 $.tags 0
"\"user\""

# Find index of value
JSON.ARRINDEX user:1001 $.tags '"vip"'
(integer) 1

# Trim array (keep indices 0-1)
JSON.ARRTRIM user:1001 $.tags 0 1

6. String Operations

String Commands

JSON.SET user:1001 $ '{"bio":"Hello"}'

# Append to string
JSON.STRAPPEND user:1001 $.bio '" World"'
(integer) 11  # New length

# Get string length
JSON.STRLEN user:1001 $.bio
(integer) 11  # "Hello World"

7. Object Operations

Object Commands

JSON.SET user:1001 $ '{"name":"John","email":"john@example.com"}'

# Get all keys
JSON.OBJKEYS user:1001 $
1) "name"
2) "email"

# Get key count
JSON.OBJLEN user:1001 $
(integer) 2

# Merge objects (Redis 7.2+)
JSON.MERGE user:1001 $ '{"phone":"123-456-7890","verified":true}'
OK

8. Type Checking

JSON.TYPE

JSON.SET data $ '{"str":"hello","num":42,"arr":[1,2,3],"obj":{"a":1},"flag":true,"empty":null}'

JSON.TYPE data $.str     # "string"
JSON.TYPE data $.num     # "integer"
JSON.TYPE data $.arr     # "array"
JSON.TYPE data $.obj     # "object"
JSON.TYPE data $.flag    # "boolean"
JSON.TYPE data $.empty   # "null"

9. CLI vs Redimo

JSON in CLI is still JSON - escaped quotes, no syntax highlighting, hard to navigate nested structures.

CLI Output

127.0.0.1:6379> JSON.GET user:1001
"{\"name\":\"John\",\"profile\":{\"settings\":{\"theme\":\"dark\",\"notifications\":{\"email\":true,\"push\":false}}}}"

# Even with INDENT it's hard to navigate

Redimo View

  • • JSON rendered as expandable tree
  • • Click to edit any nested value
  • • Syntax highlighting
  • • Type indicators (string, number, boolean)
  • • Copy path to any field

10. Common Patterns

User Profile

# Store complete profile
JSON.SET user:1001 $ '{
  "name": "John Doe",
  "email": "john@example.com",
  "preferences": {
    "theme": "dark",
    "language": "en",
    "notifications": {
      "email": true,
      "push": false
    }
  },
  "roles": ["user", "admin"]
}'

# Update single preference
JSON.SET user:1001 $.preferences.theme '"light"'

# Add a role
JSON.ARRAPPEND user:1001 $.roles '"moderator"'

# Get just preferences
JSON.GET user:1001 $.preferences

Shopping Cart

# Initialize cart
JSON.SET cart:user:1001 $ '{
  "items": [],
  "total": 0
}'

# Add item
JSON.ARRAPPEND cart:user:1001 $.items '{"productId":"P001","qty":2,"price":29.99}'
JSON.NUMINCRBY cart:user:1001 $.total 59.98

# Update quantity
JSON.SET cart:user:1001 '$.items[0].qty' '3'

# Remove item by index
JSON.ARRPOP cart:user:1001 $.items 0

Quick Reference

CommandPurpose
JSON.SETStore/update value at path
JSON.GETRetrieve value(s) at path(s)
JSON.DELDelete value at path
JSON.NUMINCRBYIncrement number
JSON.ARRAPPENDAppend to array
JSON.ARRPOPPop from array
JSON.TYPEGet JSON type at path

Work with JSON

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Continue Learning

Beginner

GET & SET

Store and retrieve string values - the foundation of Redis

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HSET & HGET

Store objects as field-value pairs without JSON serialization

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LPUSH & RPUSH

Ordered collections for queues, stacks, and activity feeds

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SADD & SMEMBERS

Unique collections with powerful set operations

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