Crate json_rules_engine

Simple rules engine that represents requirements as a tree, with each node having one or more requirements in order to be “Met”.

A tree of rules is constructed, and then the .check_json() method is called. json is a nested field: value that will be given to each node in the tree for testing.

Status output can be either Met, NotMet, or Unknown if the tested field is not present in the json.

To construct a tree, see the following methods.

Example

extern crate json_rules_engine;
use serde_json::json;

let tree = json_rules_engine::and(vec![
    json_rules_engine::string_equals("name", "John Doe"),
    json_rules_engine::or(vec![
        json_rules_engine::int_equals("fav_number", 5),
        json_rules_engine::int_in_range("thinking_of", 5, 10)
    ])
]);
let mut facts = json!({
    "name": "John Doe",
    "fav_number": 5
});
#[cfg(not(feature = "eval"))]
{
    let result = tree.check_value(&facts);
    println!("{:?}", result);
    assert!(result.status == json_rules_engine::Status::Met);
}
// result = ConditionResult { name: "And", status: Met, children: [ConditionResult { name: "Name is John Doe", status: Met, children: [] }, ConditionResult { name: "Or", status: Met, children: [ConditionResult { name: "Favorite number is 5", status: Met, children: [] }, ConditionResult { name: "Thinking of a number between 5 and 10", status: Unknown, children: [] }] }] }

This creates a tree like the following:

                             +---------+
                             |   AND   |
                             +---------+
          _____________________/\_______________
         |                                      |
         V                                      V
+-------------------+                       +--------+
| Name is John Doe  |                       |   OR   |
+-------------------+                       +--------+
| field: "name"     |             ______________/\___________
| value: "John Doe" |            |                           |
+-------------------+            V                           V
                      +----------------------+  +-------------------------+
                      | Favorite number is 5 |  | Number between 5 and 10 |
                      +----------------------+  +-------------------------+
                      | field: "fav_number"  |  | field: "thinking_of"    |
                      | value: 5             |  | start: 5                |
                      +----------------------+  | end: 10                 |
                                                +-------------------------+

Structs

CoalescenceEvent

ConditionResult

Result of checking a rules tree.

Engine

Event

Rule

RuleResult

Enums

Condition

Constraint

Error

Status

The status of a rule check

Traits

EventTrait

Functions

and

Creates a Rule where all child Rules must be Met

at_least

Creates a Rule where n child Rules must be Met

bool_equals

Creates a rule for boolean comparison.

float_contains

float_does_not_contain

float_equals

Creates a rule for float comparison.

float_greater_than

float_greater_than_inclusive

float_in

float_in_range

float_less_than

float_less_than_inclusive

float_not_equals

float_not_in

float_not_in_range

int_contains

int_contains_all

int_contains_any

int_does_not_contain

int_does_not_contain_any

int_equals

Creates a rule for int comparison.

int_greater_than

int_greater_than_inclusive

int_in

int_in_range

int_less_than

int_less_than_inclusive

int_not_equals

int_not_in

int_not_in_range

or

Creates a Rule where any child Rule must be Met

string_contains

string_contains_all

string_contains_any

string_does_not_contain

string_does_not_contain_any

string_equals

Creates a rule for string comparison

string_in

string_not_equals

string_not_in

Type Aliases

Result