treepath 0.0.0.dev2

A dev tool for performing queries on json objects.

treepath is a query language for selecting nodes from a json data-structure. The query expressions are similar to jsonpath and
Xpath, but are written in python syntax.

Solar System Sample Data

The sample data use by the examples in this README.

solar_system = { ... }

{
  "star": {
    "name": "Sun",
    "Equatorial diameter": 109.168,
    "planets": {
      "inner": [
        {
          "name": "Mercury",
          "Equatorial diameter": 0.383,
          "has-moons": false
        },
        {
          "name": "Venus",
          "Equatorial diameter": 0.949,
          "has-moons": false
        },
        {
          "name": "Earth",
          "Equatorial diameter": 1.000,
          "has-moons": true
        },
        {
          "name": "Mars",
          "Equatorial diameter": 0.532,
          "has-moons": true
        }
      ],
      "outer": [
        {
          "name": "Jupiter",
          "Equatorial diameter": 11.209,
          "has-moons": true
        },
        {
          "name": "Saturn",
          "Equatorial diameter": 9.449,
          "has-moons": true
        },
        {
          "name": "Uranus",
          "Equatorial diameter": 4.007,
          "has-moons": true
        },
        {
          "name": "Neptune",
          "Equatorial diameter": 3.883,
          "has-moons": true
        }
      ]
    }
  }
}

Typical example.

When working with json data-structures, there is a need to fetch specific pieces of data deep in the tree. A common approach to this problem is writing structural code. This approach can become quite complex depending on the json structure and search criteria.

A more declarative approach would be to use a query language as it does a better job at communicating the intent of what is being searched for.

Here are two examples that fetched the planet Earth from the sample solar-system data defined above. One is structural code, and the other is query declaration.

Structured Python Syntax	declarative Python Syntax Using treepath
def get_planet(name, the_solar_system): try: inner = the_solar_system['star']['planets']['inner'] for planet in inner: if name == planet.get('name', None): return planet except KeyError: pass raise Exception(f"The planet {name} not found") earth = get_planet('Earth', solar_system)	earth = get(path.star.planets.inner[wc][has(path.name == 'Earth')], solar_system)

Both examples will return the following results; however, the declarative approach uses only one line of code to construct the same search algorithm.

{'name': 'Earth', 'Equatorial diameter': 1.0, 'has-moons': True}

query example.

Description	Xpath	jsonpath	treepath
Find planet earth.	/star/planets/inner[name='Earth']	$.star.planets.inner[?(@.name=='Earth')]	path.star.planets.inner[wc][has(path.name == 'Earth')]
List the names of the inner planets.	/star/planets/inner[*].name	$.star.planets.inner[*].name	path.star.planets.inner[wc].name
List the names of all planets.	/star/planets/*/name	$.star.planets.[*].name	path.star.planets.wc[wc].name
List the names of all the celestial bodies.	//name	$..name	path.rec.name
List all nodes in the tree Preorder	//*	$..	path.rec
Get the third rock from the sun	/star/planets/inner[3]	$.star.planets.inner[2]	path.star.planets.inner[2]
List first two inner planets	/star/plnaets.inner[position()<3]	$.star.planets.inner[:2]	path.star.planets.inner[0:2]
		$.star.planets.inner[0, 1]	path.star.planets.inner[0, 2]
List planets smaller than earth	/star/planets/inner[Equatorial_diameter < 1]	$.star.planets.inner[?(@.['Equatorial diameter'] < 1)]	path.star.planets.inner[wc][has(path["Equatorial diameter"] < 1)]
List celestial bodies that have planets.	//*[planets]/name	$..*[?(@.planets)].name	path.rec[has(path.planets)].name