cel-go入门之实现一个简易的规则判断

代码简介

年龄大于20且商品价格大于30可以进行购买

代码

package main

import (
    "fmt"
    "log"

    "github.com/google/cel-go/cel"
    "github.com/google/cel-go/common/types"

    "github.com/google/cel-go/common/types/ref"
)

var (
    userMap = map[int64]int{
        1: 20,
    }
    goodsMap = map[int64]int{
        1: 30,
    }
)

func age(userID int64) int {
    return userMap[userID]
}

func price(goodsID int64) int {
    return goodsMap[goodsID]
}

func main() {
    env, err := cel.NewEnv(
        cel.Variable("user_id", cel.IntType),
        cel.Function("age",
            cel.Overload("age",
                []*cel.Type{cel.IntType},
                cel.IntType,
                cel.UnaryBinding(func(val ref.Val) ref.Val {
                    return types.Int(age(val.Value().(int64)))
                },
                ),
            ),
        ),

        cel.Variable("goods_id", cel.IntType),
        cel.Function("price",
            cel.Overload("price",
                []*cel.Type{cel.IntType},
                cel.IntType,
                cel.UnaryBinding(func(val ref.Val) ref.Val {
                    return types.Int(price(val.Value().(int64)))
                },
                ),
            ),
        ),
    )
    if err != nil {
        log.Fatalf("environment error: %+v\n", err)
    }
    ast, iss := env.Compile(`age(user_id) >= 20 && price(goods_id) >= 30`)
    if iss.Err() != nil {
        log.Fatalln(iss.Err())
    }
    prg, err := env.Program(ast)
    if err != nil {
        log.Fatalf("Program error: %+v\n", err)
    }

    out, _, err := prg.Eval(map[string]any{
        "user_id":  1,
        "goods_id": 1,
    })
    if err != nil {
        log.Fatalf("Eval error: %+v\n", err)
    }

    fmt.Println(out)
}