Rule.js: Expression Language
A simple language for expressing business rules.
API
This module exports a single function. The function accepts an optional
constructor for the @rule.js/core module.
Example:
const Rule = require('@rule.js/core').extend({}, {
elasticsearch: require('@rule.js/elasticsearch')
})
const ruleExpression = require('@rule.js/expression')(Rule)
const rule = ruleExpression('"name" equal "sample"')
const query = rule.elasticsearch()
// query:
// {
// "bool": {
// "must": [
// {
// "term": {
// "name": "sample"
// }
// }
// ]
// }
// }Language
The language is meant to be easy enough for non-programmers to pick up. There are no functions or other more complex constructs.
Literals
There are currently only two types of literals: strings and booleans. Strings
must always be double quoted. To place a double quote inside of a string, an
escape sequence must be used (\").
Valid:
"hello""this is \"a quote\"""this is a backslash: \\"
Invalid:
'single quotes'"hello "quotes""
Comparison Operators
equal
Tests if the key is equal to the given property.
Example:
"enabled" equal true
not equal
Compares if the key is not equal to the given property.
Example:
"status" not equal "disabled"
is empty
Tests if the given key is empty.
Example:
"quantity" is empty
is not empty
Inversion of the is empty operator.
Example:
"quantity" is not empty
any
Tests if the key is equal any of the given values.
Example:
"status" any ("open", "draft")
not any
Test if the given key is not equal any of the specified values.
Example:
"status" not any ("pending", "new")
contains
Test if the key contains the given value.
Example:
"hobbies" contains "Guitar"
not contains
Inverse of the contains operator.
Example:
"hobbies" not contains "Guitar"
greater than
Test if the key is less than the specified value.
Example:
"age" less than 21
less than
Test if the key is greater than the specified value.
Example:
"income" greater than 55374.19
Logical Operators
and
Combines two rules together. If one of them is false, the result from the operator will be false.
Example:
"quantity" is not empty and "status" not equal "disabled"
or
Combines two rules togther. If one of them is truthful, the result from the operator will be true.
Example:
"quantity" is empty or "status" equal "disabled"
You can mix logical operators together. For example:
"quantity" is empty or "status" is empty and "owner" is empty
Keys
You can do deep lookups with the following:
"person"."name" equal "Rick"