Gin&Tonic

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Introduction

Gin&Tonic is a LemonSqueezy webhook library for gin framework that lets you build LemonSqueezy webhooks quickly and elegantly

Quick start

Installation

go get -u github.com/YianAndCode/gintonic

Import

import "github.com/YianAndCode/gintonic"

Write your bussines code

import (
	"context"
	"fmt"

	"github.com/YianAndCode/gintonic"
	"github.com/YianAndCode/gintonic/lmdata"
)

var _ gintonic.OrderCreatedHandler = OrderCreated

func OrderCreated(ctx context.Context, meta lmdata.Meta, data lmdata.Order) error {
	fmt.Printf("You made a sale! Total amount is %s\n", data.Attributes.TotalFormatted)
	return nil
}

Register routes to gin and run

func main() {
	r := gin.New()
	r.Use(gin.Recovery())

	gt := gintonic.New(
		"[Load secret from somewhere]",
		gintonic.WithOrderCreatedHandler(OrderCreated),
	)
	r.POST("/lemonsqueezy/webhook", gt.LemonSqueezyWebhook)

	r.Run()
}

Definition

Instantiate

You can get an instantce of gintonic just by the New function, and the first parameter is fixed as secret, then you can set any handlers as needed:

gt := gintonic.New(
    "[YOUR_SECRET]",
    gintonic.WithOrderCreatedHandler(OrderCreated), // The handler for orcer_created event
    gintonic.WithDefaultHandler(DefaultHandler),    // The default handler
)

Setting handler is done using the gintonic.With[EventName]Handler() option functions, the specific functions can be found in option.go

Handler

Handler definitions are in handler.go, divided into two types: Event Handler and DefaultHandler.

Their relationship is like case and default in a switch statement. When instantiating a gintonic instance with New, the Handler registered using gintonic.WithXXXHandler(XXX) can be considered a case. When receiving a webhook event, gintonic will judge which case it belongs to and then call the corresponding handler. If it cannot find one, it will look for a DefaultHandler. If it cannot find the corresponding Event Handler and no DefaultHandler is set, then it will return an error.

DefaultHandler is defined as:

type DefaultHandler func(ctx context.Context, eventName string, meta lmdata.Meta, data interface{}) error

Event Handler is like:

type OrderCreatedHandler func(ctx context.Context, meta lmdata.Meta, data lmdata.Order) error

The only diffrence is the type of data.

Core

gintonic interacts with gin using the GinTonic.LemonSqueezyWebhook method. This method will read HTTP Headers and POST body from gin, then verify the signature. After passing verification, it dispatches events to the registered handler.

So we just need to register the LemonSqueezyWebhook method of the GinTonic instance to a route in gin.