Appends one or more values to the end of a JSON array at the specified path.
Usage
const newLength = await redis.json.arrappend("user:123", "$.tags", "premium", "verified");
Arguments
The key containing the JSON document
JSONPath expression pointing to the array to append to
One or more values to append to the array. Can be any JSON-serializable values.
Response
An array of numbers representing the new length of the array at each matching path. Returns null for paths that don’t exist or aren’t arrays.
Examples
Append single value to array
// Initial: { "tags": ["developer", "admin"] }
const newLength = await redis.json.arrappend("user:123", "$.tags", "premium");
console.log(newLength); // [3]
// Result: { "tags": ["developer", "admin", "premium"] }
Append multiple values
const newLength = await redis.json.arrappend(
"user:123",
"$.tags",
"verified",
"active",
"pro"
);
console.log(newLength); // [6]
// Result: { "tags": ["developer", "admin", "premium", "verified", "active", "pro"] }
Append to nested array
interface Order {
id: string;
items: string[];
}
const newLength = await redis.json.arrappend(
"order:456",
"$.items",
"item-123"
);
console.log(newLength); // [4]
Append objects to array
interface Product {
id: string;
name: string;
price: number;
}
const newProduct: Product = {
id: "prod-789",
name: "Widget",
price: 29.99
};
const newLength = await redis.json.arrappend(
"cart:123",
"$.products",
newProduct
);
Append to multiple arrays (wildcard path)
// Initial: {
// "users": [
// { "id": 1, "tags": ["active"] },
// { "id": 2, "tags": ["inactive"] }
// ]
// }
const newLengths = await redis.json.arrappend(
"data:1",
"$.users[*].tags",
"updated"
);
console.log(newLengths); // [2, 2]
// Result: Both users now have "updated" tag appended
Handle non-existent paths
const newLength = await redis.json.arrappend(
"user:123",
"$.nonexistent",
"value"
);
console.log(newLength); // [null]
JSONPath Syntax
$.array - Append to a top-level array$.nested.array - Append to a nested array$.array[0].items - Append to array within array element$..array - Append to all matching arrays recursively$.items[*].tags - Append to arrays within each item
Notes
- The path must point to an existing array. If the path doesn’t exist or points to a non-array value,
null is returned for that path.
- When using wildcard paths, the operation is performed on all matching arrays.
- Values are automatically JSON-serialized before appending.
See Also