jwadhams / json-logic-php
Build rules with complex comparisons and boolean operators, serialized as JSON, and execute them in PHP
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Requires
- php: >=7.2.0
Requires (Dev)
- phpunit/phpunit: ^9.3.3
This package is auto-updated.
Last update: 2024-12-09 16:21:16 UTC
README
This parser accepts JsonLogic rules and executes them in PHP.
The JsonLogic format is designed to allow you to share rules (logic) between front-end and back-end code (regardless of language difference), even to store logic along with a record in a database. JsonLogic is documented extensively at JsonLogic.com, including examples of every supported operation and a place to try out rules in your browser.
The same format can also be executed in JavaScript by the library json-logic-js
Examples
A note about types
This is a PHP interpreter of a format designed to be transmitted and stored as JSON. So it makes sense to conceptualize the rules in JSON.
Expressed in JSON, a JsonLogic rule is always one key, with an array of values.
{"==" : ["apples", "apples"]}
PHP has a way to express associative arrays as literals, and no object equivalent, so all these examples are written as if JsonLogic rules were decoded with json_decode
's $assoc
parameter set true, e.g.
json_decode('{"==" : ["apples", "apples"]}', true); // ["==" => ["apples", "apples"]]
The library will happily accept either associative arrays or objects:
$rule = '{"==":["apples", "apples"]}'; //Decode the JSON string to an array, and evaluate it. JWadhams\JsonLogic::apply( json_decode($rule, true) ); // true //Decode the JSON string to an object, and evaluate it. JWadhams\JsonLogic::apply( json_decode($rule, false) ); // true
Simple
JWadhams\JsonLogic::apply( [ "==" => [1, 1] ] ); // true
This is a simple test, equivalent to 1 == 1
. A few things about the format:
- The operator is always in the "key" position. There is only one key per JsonLogic rule.
- The values are typically an array.
- Each value can be a string, number, boolean, array, or null
Compound
Here we're beginning to nest rules.
JWadhams\JsonLogic::apply( [ "and" => [ [ ">" => [3,1] ], [ "<" => [1,3] ] ] ] ); // true
In an infix language (like PHP) this could be written as:
( (3 > 1) and (1 < 3) )
Data-Driven
Obviously these rules aren't very interesting if they can only take static literal data. Typically JsonLogic::apply
will be called with a rule object and a data object. You can use the var
operator to get attributes of the data object:
JWadhams\JsonLogic::apply( [ "var" => ["a"] ], // Rule [ "a" => 1, "b" => 2 ] // Data ); // 1
If you like, we support syntactic sugar on unary operators to skip the array around values:
JWadhams\JsonLogic::apply( [ "var" => "a" ], [ "a" => 1, "b" => 2 ] ); // 1
You can also use the var
operator to access an array by numeric index:
JWadhams\JsonLogic::apply( [ "var" => 1 ], [ "apple", "banana", "carrot" ] ); // "banana"
Here's a complex rule that mixes literals and data. The pie isn't ready to eat unless it's cooler than 110 degrees, and filled with apples.
$rules = [ "and" => [ [ "<" => [ [ "var" => "temp" ], 110 ] ], [ "==" => [ [ "var" => "pie.filling" ], "apple" ] ] ] ]; $data = [ "temp" => 100, "pie" => [ "filling" => "apple" ] ]; JWadhams\JsonLogic::apply($rules, $data); // true
Always and Never
Sometimes the rule you want to process is "Always" or "Never." If the first parameter passed to JsonLogic::apply
is a non-object, non-associative-array, it is returned immediately.
//Always JWadhams\JsonLogic::apply(true, $data_will_be_ignored); // true //Never JWadhams\JsonLogic::apply(false, $i_wasnt_even_supposed_to_be_here); // false
Installation
The best way to install this library is via Composer:
composer require jwadhams/json-logic-php
If that doesn't suit you, and you want to manage updates yourself, the entire library is self-contained in src/JWadhams/JsonLogic.php
and you can download it straight into your project as you see fit.
curl -O https://raw.githubusercontent.com/jwadhams/json-logic-php/master/src/JWadhams/JsonLogic.php