server.go

package main

import (
	"context"
	"github.com/99designs/gqlgen/graphql/handler"
	"github.com/99designs/gqlgen/graphql/playground"
	"github.com/aws/aws-lambda-go/events"
	"github.com/aws/aws-lambda-go/lambda"
	ginadapter "github.com/awslabs/aws-lambda-go-api-proxy/gin"
	"github.com/gin-gonic/gin"
	"github.com/spachava753/gqlgen-todos/graph"
	"github.com/spachava753/gqlgen-todos/graph/generated"
	"log"
)

var ginLambda *ginadapter.GinLambda

// Defining the Graphql handler
func graphqlHandler() gin.HandlerFunc {
	// NewExecutableSchema and Config are in the generated.go file
	// Resolver is in the resolver.go file
	h := handler.NewDefaultServer(generated.NewExecutableSchema(generated.Config{Resolvers: &graph.Resolver{}}))

	return func(c *gin.Context) {
		h.ServeHTTP(c.Writer, c.Request)
	}
}

// Defining the Playground handler
func playgroundHandler() gin.HandlerFunc {
	h := playground.Handler("GraphQL", "/query")

	return func(c *gin.Context) {
		h.ServeHTTP(c.Writer, c.Request)
	}
}

func Handler(ctx context.Context, req events.APIGatewayProxyRequest) (events.APIGatewayProxyResponse, error) {
	// If no name is provided in the HTTP request body, throw an error
	if ginLambda == nil {
		// stdout and stderr are sent to AWS CloudWatch Logs
		log.Printf("Gin cold start")
		r := gin.Default()
		// Setting up Gin
		r.POST("/query", graphqlHandler())
		r.GET("/playground", playgroundHandler())
		r.GET("/ping", func(c *gin.Context) {
			log.Println("Handler!!")
			c.JSON(200, gin.H{
				"message": "pong",
			})
		})

		ginLambda = ginadapter.New(r)
	}

	return ginLambda.ProxyWithContext(ctx, req)
}

func main() {
	// Setting up Gin
	lambda.Start(Handler)
}