JEMSPath

JMESPath (pronounced “James path”) is a query language for JSON. It allows you to declaratively specify how to extract elements from a JSON document.

Unlike jq, which is a standalone CLI tool, JMESPath is often used as a library embedded in other languages (Python, JavaScript, Go, etc.) or tools (AWS CLI).

Key Features

Declarative: Describe what you want, not how to get it.
Portable: Implementations available in many languages.

Examples

Given the following JSON:

{
  "locations": [
    {"name": "Seattle", "state": "WA"},
    {"name": "New York", "state": "NY"},
    {"name": "Bellevue", "state": "WA"},
    {"name": "Olympia", "state": "WA"}
  ]
}

Basic Expressions

Select list: locations
Filter list: locations[?state == 'WA']
- Result: [{"name": "Seattle", "state": "WA"}, ...]
Projection (Map): locations[*].name
- Result: ["Seattle", "New York", "Bellevue", "Olympia"]
Filter & Project: locations[?state == 'WA'].name
- Result: ["Seattle", "Bellevue", "Olympia"]

Python Usage

import jmespath

data = {"foo": {"bar": "baz"}}
result = jmespath.search('foo.bar', data)
print(result) # "baz"

RTFM

JMESPath Tutorial - The best place to start.
JMESPath Specification
parsel - A library that wraps JMESPath and XPath.