trigger

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

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

• [x] Full Text Search Expression Macros/Functions(startsWith, endsWith, contains)
• [x] RegularExp Expression Macros/Functions(matches)
• [x] Geographic Expression Macros/Functions(geoDistance)
• [x] Cryptographic Expression Macros/Functions(encrypt, decrypt, sha1, sha256, sha3)
• [x] JWT Expression Macros/Functions(parseClaims, parseHeader, parseSignature)
• [x] Collection Expression Macros/Functions(in, map, filter, exists)
• [x] String Manipulation Expression Macros/Functions(replace, join, titleCase, lowerCase, upperCase, trimSpace, trimPrefix, trimSuffix, render)
• [x] 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": "bob@gmail.com",
	})
	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": "bob@acme.com",
		"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