JSON pick pointers

json-pick-pointers · version 1.0.0 · JSON & JSONL · free, no key needed

Pick cloned JSON values at explicit RFC 6901 pointers into a null-prototype map.

Use when you need to: json pick pointers · project json pointers · select json pointers.

Supported

• json pick pointers
• project json pointers
• select json pointers

Not supported

• reconstruct nested tree
• create missing
• json patch

Behavior

• Accept only JSON values: null, boolean, finite number, string, array, and plain objects.
• Reject NaN, Infinity, -Infinity, undefined, BigInt, functions, symbols, Date, Map, Set, RegExp, boxed primitives, Buffer, and sparse holes.
• Canonicalize -0 to 0.
• Objects may have null or Object.prototype; use own enumerable string keys only.
• Treat __proto__, constructor, and toString as ordinary own keys. Never mutate Object.prototype.
• Output objects must be Object.create(null). Deep-clone all returned JSON values.
• Bound walk: max depth 32, max nodes 10000, max UTF-8 JSON bytes 250KiB of the input document string if provided as text; when json is already a value, bound the walked node count and depth.
• pointers is a non-empty unique list. Duplicate pointers are invalid_input.
• Each pointer is resolved as json-pointer-get. Missing paths are invalid_input.
• Result values is a null-prototype object whose own keys are the pointer strings and whose values are deep clones.
• Pointer strings used as keys, including empty string for root, are ordinary own keys.

Input

• json (any JSON value, required)
• pointers (array of string, required): min items 1; max items 256; each max length 1024

Output

• values (object, required)

Limits

• max json depth: 32
• max json nodes: 10000
• max pointers: 256
• max pointer chars: 1024

Example

Request input:

{
  "json": {
    "a": 1,
    "b": {
      "c": 2
    }
  },
  "pointers": [
    "/a",
    "/b/c"
  ]
}

Response:

{
  "result": {
    "values": {
      "/a": 1,
      "/b/c": 2
    }
  }
}

How to call it

MCP

Connect https://computefirst.net/mcp (setup), then call execute with:

{
  "id": "json-pick-pointers",
  "version": "1.0.0",
  "input": {
    "json": {
      "a": 1,
      "b": {
        "c": 2
      }
    },
    "pointers": [
      "/a",
      "/b/c"
    ]
  }
}

HTTP (no key)

curl -X POST https://computefirst.net/v1/tools/json-pick-pointers/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"json":{"a":1,"b":{"c":2}},"pointers":["/a","/b/c"]}'

The machine-readable contract is at /v1/tools/json-pick-pointers/versions/1.0.0.

CLI

node cli.mjs run json-pick-pointers 1.0.0 --input input.json --base-url https://computefirst.net

Get the client at /clients/cli/.

Related tools

• JSON array project: Select specific keys from each object in a JSON array.
• JSON array filter equals: Filter JSON array objects where a key equals a specific value.
• JSON flatten: Flatten a JSON value into a null-prototype map keyed by RFC 6901 JSON Pointers.
• JSON omit pointers: Deep-clone JSON and delete values at explicit RFC 6901 pointers.
• JSON pointer list: List RFC 6901 pointers to every reachable JSON node, root first.
• JSON unflatten: Reconstruct a JSON value from a map of RFC 6901 JSON Pointers to leaves.