eval

README

eval

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

Documentation

Index

• Variables
• type Decision
  • func NewDecision(expression string) (*Decision, error)
  • func (n *Decision) Eval(data map[string]interface{}) error
  • func (e *Decision) Expression() string
• type Trigger
  • func NewTrigger(decision *Decision, triggerExpression string) (*Trigger, error)
  • func (e *Trigger) Expression() string
  • func (t *Trigger) Trigger(data map[string]interface{}) (map[string]interface{}, error)

Examples

• NewDecision
• NewTrigger

Variables

var (
	ErrDecisionDenied   = errors.New("eval: evaluation = false")
	ErrEmptyExpressions = errors.New("eval: empty expressions")
)

Types

type Decision

type Decision struct {
	// contains filtered or unexported fields
}

Decision is used to evaluate boolean expressions

func NewDecision

func NewDecision(expression string) (*Decision, error)

NewDecision creates a new Decision with the given boolean CEL expressions

Example

package main

import (
	"fmt"
	"github.com/graphikDB/eval"
)

func main() {
	decision, err := eval.NewDecision("this.email.endsWith('acme.com')")
	if err != nil {
		fmt.Println(err.Error())
		return
	}
	if err := decision.Eval(map[string]interface{}{
		"name":  "bob",
		"email": "bob@acme.com",
	}); err != nil {
		fmt.Println(err.Error())
		return
	}
	fmt.Println(decision.Expression())
}

Output:

this.email.endsWith('acme.com')

func (*Decision) Eval

func (n *Decision) Eval(data map[string]interface{}) error

Eval evaluates the boolean CEL expressions against the Mapper

func (*Decision) Expression

func (e *Decision) Expression() string

Expressions returns the decsions raw expression

type Trigger

type Trigger struct {
	// contains filtered or unexported fields
}

Trigger creates values as map[string]interface{} if it's decisider returns no errors against a Mapper

func NewTrigger

func NewTrigger(decision *Decision, triggerExpression string) (*Trigger, error)

NewTrigger creates a new trigger instance from the decision & trigger expressions

Example

package main

import (
	"fmt"
	"github.com/graphikDB/eval"
)

func main() {
	decision, err := eval.NewDecision("this.email.endsWith('acme.com')")
	if err != nil {
		fmt.Println(err.Error())
		return
	}
	trigg, err := eval.NewTrigger(decision, `
	{
		'admin': true,
		'updated_at': now(),
		'email_hash': sha1(this.email)
	}
`)
	if err != nil {
		fmt.Println(err.Error())
		return
	}
	person := map[string]interface{}{
		"name":  "bob",
		"email": "bob@acme.com",
	}
	data, err := trigg.Trigger(person)
	if err != nil {
		fmt.Println(err.Error())
		return
	}
	fmt.Println(data["admin"], data["updated_at"].(int64) > 0, data["email_hash"])
}

Output:

true true 6fd706dd2d151c2bf79218a2acd764a7d3eed7e3

func (*Trigger) Expression

func (e *Trigger) Expression() string

Expression returns the triggers raw CEL expressions

func (*Trigger) Trigger

func (t *Trigger) Trigger(data map[string]interface{}) (map[string]interface{}, error)

Trigger executes it's decision against the Mapper and then overwrites the