【Golang】初心者がAPIを作ってみる

go version

go mod init api

go mod tidy

${ROOT}
├── data
│   └── questions.db
├── go.mod
├── go.sum
├── main.go
└── model
    └── db_model.go

package model

import (
	"github.com/jinzhu/gorm"
    // db_model.goでは使わないが，内部的に使われるためここでimportしておく
	_ "github.com/mattn/go-sqlite3"
)

type Question struct {
    // 大文字にしなければ値が取得できない
	ID         int    `gorm:"primary_key"`
	Year       int    `gorm:"not null"`
	Genre      string `gorm:"not null"`
	Question   string `gorm:"not null"`
	Answer     string `gorm:"not null"`
	Commentary string `gorm:"not null"`
}

func GetAll() []Question {
	db, err := gorm.Open("sqlite3", "data/questions.db")
	if err != nil {
		panic("failed to connect database")
	}

	questions := []Question{}

    // 全ての値を取得
	db.Find(&questions)

	return questions
}

func GetBy(tag string, num string) []Question {
	db, err := gorm.Open("sqlite3", "data/questions.db")
	if err != nil {
		panic("failed to connect database")
	}
	defer db.Close()

	questions := []Question{}
	db.Where(fmt.Sprintf("%s = ?", tag), num).Find(&questions)

	return questions
}

package main

import (
	"api/model"

	"github.com/gin-gonic/gin"
)

func main() {
	r := gin.Default()

	r.GET("/questions", func(c *gin.Context) {
        // 値を取得する
		questins := db_model.GetAll()
        // JSONで返す
		c.JSON(200, questins)
	})
	r.GET("/:tag/:num", func(c *gin.Context) {
		tag := c.Param("tag")
		num := c.Param("num")
		question := model.GetBy(tag, num)
		c.JSON(200, question)
	})

	r.Run()
}

// http://localhost:8080/questions
[{"ID":1,"Year":2022,"Genre":"臨床生理学","Question":"問い1","Answer":"答え1","Commentary":"コメント1"},{"ID":2,"Year":2022,"Genre":"臨床血液学","Question":"問い2","Answer":"答え2","Commentary":"コメント2"}]

// http://localhost:8080/id/1
[{"ID":1,"Year":2022,"Genre":"臨床生理学","Question":"問い1","Answer":"答え1","Commentary":"コメント1"}]