JMESPath-Jsonnet: it's JMESPath in Jsonnet

Description

JMESPath is a way of getting specific values out of JSON documents. It has some support for generating JSON as the result. See http://jmespath.org

Jsonnet is a powerful, functional programming language whose output is JSON that is typically used to generate configuration. See http://jsonnet.org

JMESPath-Jsonnet is the Reese's Peanut Butter Cups of these. It provides a concice way to query values within a Jsonnet structure, but that's not all. It also supports generating modified documents, with JMESPath queries selecting elements for modification.

Usage

Search

local jmespath = import 'jmespath.libsonnet';
local input = {
  foo: ['bar', 'baz'],
};

// Returns 'baz'
jmespath.search('foo[1]', input)

Set

local jmespath = import 'jmespath.libsonnet';
local input = {
  foo: ['bar', 'baz'],
};

// Returns this modified document:
// {
//   foo: ['bar', 'qux'],
// };

jmespath.set('foo[1]', input, 'qux')

Using a precompiled expression

local jmespath = import 'jmespath.libsonnet';
local compiled = jmespath.compile('foo[1]');
local input = {
  foo: ['bar', 'baz'],
};

// Returns this modified document:
// {
//   foo: ['bar', 'qux'],
// };

jmespath.set(compiled, input, 'qux')

Implementation status

JMESPath-Jsonnet currently supports a subset of JMESPath funtionality, including:

identifiers
double-quoted identifiers
indexing
slices
flatten projections
object and array wildcard projections
filter projections
subexpressions
pipes
json literals
single-quoted strings
functions (except those that require expression type)

missing:

or-expressions
and-expressions
expression type (&foo.bar)
multiselect
- This is a lower priority because Jsonnet is already quite good at generating JSON.

abentley / jmespath-jsonnet