github.com/graphikdb/eval

trigger

https://graphikdb.github.io/trigger/

a decision & trigger framework backed by Google's Common Expression Language used in graphikDB

• Full Text Search Expression Macros/Functions(startsWith, endsWith, contains)
• RegularExp Expression Macros/Functions(matches)
• Geographic Expression Macros/Functions(geoDistance)
• Cryptographic Expression Macros/Functions(encrypt, decrypt, sha1, sha256, sha3)
• JWT Expression Macros/Functions(parseClaims, parseHeader, parseSignature)
• Collection Expression Macros/Functions(in, map, filter, exists)
• String Manipulation Expression Macros/Functions(replace, join, titleCase, lowerCase, upperCase, trimSpace, trimPrefix, trimSuffix, render)
• URL Introspection Expression Macros/Functions(parseHost, parseScheme, parseQuery, parsePath)

Use Case:

Since this expression language requires just input data(map[string]interface) and an expression string, Go programs may use it to embed flexible logic that may be changed at runtime without having to recompile.

• Authorization Middleware/Policy Evaluation/Rule Engine

• Database or API "triggers" for mutating data before its commited

• Search Engine(filter something based on a decision)

Examples

restrict access based on domain

	decision, err := trigger.NewDecision("this.email.endsWith('acme.com')")
	if err != nil {
		fmt.Println(err.Error())
		return
	}
	err = decision.Eval(map[string]interface{}{
		"email": "[e-mail]",
	})
	fmt.Println(err == trigger.ErrDecisionDenied) 
    // Output: true 

create a trigger based on signup event that adds updated_at timestamp & hashes a password

	// create a trigger based on the new decision that hashes a password and creates an updated_at timestamp
	// this would in theory be applied to a newly created user after signup
	trigg, err := trigger.NewArrowTrigger(`
	this.event == 'signup' && has(this.email) =>
	{
		'updated_at': now(),
		'password': this.password.sha1()
	}
`)
	if err != nil {
		fmt.Println(err.Error())
		return
	}

	user := map[string]interface{}{
		"event": "signup",
		"name":  "bob",
		"email": "[e-mail]",
		"password": "123456",
	}
	data, err := trigg.Trigger(user)
	if err != nil {
		fmt.Println(err.Error())
		return
	}
	fmt.Println(data["updated_at"].(int64) > 0, data["password"])
	// Output: true 7c4a8d09ca3762af61e59520943dc26494f8941b

CEL Macro Extensions

Additional details on the standard CEL spec/library may be found here

function	notation	description
now	now() int64	current timestamp in unix secods
uuid	uuid() string	random uuidv4 string
sha1	sha1(string) string	sha1 hash of the input string
sha256	sha256(string) string	sha256 hash of the input string
sha3	sha3(string) string	sha3 hash of the input string
base64Encode	base64Encode(string) string	base64 encoded version of the input
base64Decode	base64Decode(string) string	base64 decoded version of the input
jsonEncode	jsonEncode(string) string	json encoded version of the input
jsonDecode	jsonDecode(string) string	json decoded version of the input
replace	replace(text string, old string, new string) string	full string replacement of the old value with the new value
join	join(arr list(string), sep string) string	joins the array into a single string with the given separator
titleCase	titleCase(string) string	converts the input into title case string
lowerCase	lowerCase(string) string	converts the input into lower case string
upperCase	upperCase(string) string	converts the input into upper case string
trimSpace	trimSpace(string) string	removes white spaces from the input string
trimPrefix	trimPrefix(string) string	removes prefix from the input string
trimSuffix	trimSuffix(string) string	removes suffix from the input string
geoDistance	geoDistance(this list(float64), that list(float64)) float64	haversine distance between two coordinates [lat,lng]
render	render(tmplate string, data map[string]interface) string	renders the input template with the provided data map
parseClaims	parseClaims(jwt string) map[string]interface)	returns the payload of the jwt as a map
parseHeader	parseHeader(jwt string) map[string]interface	returns the header of the jwt as a map
parseSignature	parseSignature(jwt string) string	returns the signature of the jwt as a string
typeOf	typeOf(any) string	returns the go type of the input
encrypt	encrypt(secret string, msg string) string	aes encrypt a message with a given secret
decrypt	decrypt(secret string, msg string) string	aes decrypt a message with a given secret