siphon-dsl 0.4.3

Minimal DSL for API data extraction

Siphon

A minimal DSL for extracting data from JSON APIs.

Like a siphon draws liquid from a container, Siphon draws the data you need from nested JSON structures—just define the paths, and let it flow.

Install

pip install siphon-dsl

Or with uv:

uv add siphon-dsl

Quick Start

from siphon import process

data = {
    "data": {
        "id": "prod_123",
        "items": [
            {"id": 1, "status": "active", "name": "Widget"},
            {"id": 2, "status": "inactive", "name": "Gadget"},
            {"id": 3, "status": "active", "name": "Thing"},
        ],
    }
}

spec = {
    "extract": {
        "id": "$.data.id",
        "all_active": {
            "path": "$.data.items[*]",
            "where": {"status": "active"},
            "select": {"item_id": "id", "item_name": "name"},
            "collect": True,
        },
    }
}

result = process(spec, data)

Output:

{
  "id": "prod_123",
  "all_active": [
    {"item_id": 1, "item_name": "Widget"},
    {"item_id": 3, "item_name": "Thing"}
  ]
}

Features

Feature	Syntax	Description
Simple paths	$.data.id	Extract nested values
Array iteration	$.items[*].name	Traverse arrays
Filtering	where: {status: "active"}	Filter by field values
Projection	select: {new: "old"}	Rename and reshape fields
Collect	collect: true	Return all matches (default: first only)

Spec Format

Simple extraction

extract:
  id: "$.data.id"
  name: "$.data.name"

Extended extraction

extract:
  active_items:
    path: "$.data.items[*]"
    where: {status: "active"}
    select: {item_id: "id", item_name: "name"}
    collect: true

Fetch from API

from siphon import fetch_and_process

spec = {
    "request": {"path": "/products"},
    "extract": {
        "id": "$.data.id",
        "names": {"path": "$.data.items[*].name", "collect": True},
    },
}

result = fetch_and_process(spec, "https://api.example.com")

Requires requests:

pip install siphon-dsl[http]

Typed Specs (Pydantic)

from siphon.typed import process_spec, ExtractSpec, FieldSpec

spec = ExtractSpec(
    extract={
        "id": "$.data.id",
        "active_items": FieldSpec(
            path="$.data.items[*]",
            where={"status": "active"},
            select={"item_id": "id", "name": "name"},
            collect=True,
        ),
    }
)

result = process_spec(spec, data)

Requires pydantic:

pip install siphon-dsl[typed]

Why Siphon?

• Minimal — ~100 lines of code, no dependencies
• Declarative — specs are data, not code
• Composable — combine paths, filters, and projections

Spec History

See specs/ for version history and full documentation.

License

MIT