JSONPath

This is a JSONPath implementation for PHP based on Stefan Goessner's JSONPath script.

JSONPath is an XPath-like expression language for filtering, flattening and extracting data.

I believe that this improves on the original script (which was last updated in 2007) by doing a few things:

Object-oriented code (should be easier to manage or extend in future)
Expressions are parsed into tokens using some code cribbed from Doctrine Lexer and cached
There is no eval() in use
Performance is pretty much the same
Any combination of objects/arrays/ArrayAccess-objects can be used as the data input which is great if you're de-serializing JSON in to objects or if you want to process your own data structures.

Installation

composer require flow/jsonpath

JSONPath Examples

JSONPath	Result
`$.store.books[*].author`	the authors of all books in the store
`$..author`	all authors
`$.store..price`	the price of everything in the store.
`$..books[2]`	the third book
`$..books[(@.length-1)]`	the last book in order.
`$..books[-1:]`	the last book in order.
`$..books[0,1]`	the first two books
`$..books[:2]`	the first two books
`$..books[::2]`	every second book starting from first one
`$..books[1:6:3]`	every third book starting from 1 till 6
`$..books[?(@.isbn)]`	filter all books with isbn number
`$..books[?(@.price<10)]`	filter all books cheapier than 10
`$..*`	all elements in the data (recursively extracted)

Expression syntax

Symbol	Description
`$`	The root object/element (not strictly necessary)
`@`	The current object/element
`.` or `[]`	Child operator
`..`	Recursive descent
`*`	Wildcard. All child elements regardless their index.
`[,]`	Array indices as a set
`[start:end:step]`	Array slice operator borrowed from ES4/Python.
`?()`	Filters a result set by a script expression
`()`	Uses the result of a script expression as the index

PHP Usage

$data = ['people' => [['name' => 'Joe'], ['name' => 'Jane'], ['name' => 'John']]];
$result = (new JSONPath($data))->find('$.people.*.name'); // returns new JSONPath
// $result[0] === 'Joe'
// $result[1] === 'Jane'
// $result[2] === 'John'

Magic method access

The options flag JSONPath::ALLOW_MAGIC will instruct JSONPath when retrieving a value to first check if an object has a magic __get() method and will call this method if available. This feature is iffy and not very predictable as:

wildcard and recursive features will only look at public properties and can't smell which properties are magically accessible
there is no property_exists check for magic methods so an object with a magic __get() will always return true when checking if the property exists
any errors thrown or unpredictable behaviour caused by fetching via __get() is your own problem to deal with

$jsonPath = new JSONPath($myObject, JSONPath::ALLOW_MAGIC);

For more examples, check the JSONPathTest.php tests file.

Script expressions

Script expressions are not supported as the original author intended because:

This would only be achievable through eval (boo).
Using the script engine from different languages defeats the purpose of having a single expression evaluate the same way in different languages which seems like a bit of a flaw if you're creating an abstract expression syntax.

So here are the types of query expressions that are supported:

[?(@._KEY_ _OPERATOR_ _VALUE_)] // <, >, !=, and ==
Eg.
[?(@.title == "A string")] //
[?(@.title = "A string")]
// A single equals is not an assignment but the SQL-style of '=='

Similar projects

JMESPath does similiar things, is full of features and has a PHP implementation

The Hash utility from CakePHP does some similar things

The original JsonPath implementations is available at http://code.google.com/p/jsonpath and re-hosted for composer here Peekmo/JsonPath.

ObjectPath (https://github.com/adriank/ObjectPath) appears to be a Python/JS implementation with a new name and extra features.

Changelog

0.3.0

Added JSONPathToken class as value object
Lexer clean up and refactor
Updated the lexing and filtering of the recursive token ("..") to allow for a combination of recursion and filters, eg. $..[?(@.type == 'suburb')].name

0.2.1 - 0.2.5

Various bug fixes and clean up

0.2.0

Added a heap of array access features for more creative iterating and chaining possibilities

0.1.x

Init

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