无法在Golang中编写可在多个结构上工作的泛型函数

Question

我是Go新手，正在学习接口和结构。我有两个结构-ServiceSection和SliderSection

1. 获取JSON响应并对其进行解组
2. 使用该结构使用"html/template">

因此，我正在尝试创建一个通用函数来执行可以用于多个结构的两个任务。计划再创建5-6个这样的结构。下面是我创建的代码-

package main
import (
"bytes"
"encoding/json"
"fmt"
"io/ioutil"
"log"
"net/http"
"html/template"
)

const (
getServicesAPI = "https://huyk1a44n6.execute-api.us-east-1.amazonaws.com/v1/services"
getSliderAPI   = "https://huyk1a44n6.execute-api.us-east-1.amazonaws.com/v1/home-slider"

servicesTemplate = `<div class="container">
<div class="row">
<div class="col-md-12">
<div class="section-title">
<h5>{{.Heading1}}</h5>
<h2>{{.Heading2}}</h2>
</div>
</div>
</div>
<div class="row">

{{range .Services}}
<div class="col-lg-4 col-md-6">
<a class="single-services-box" href="{{.Href}}">
<div class="services-img">
<img alt="Service Images"
src="{{.Image}}">
</div>
<h3>{{.Heading}}</h3>
</a>
</div>
{{end}}

</div>
</div>`

sliderTemplate = `    {{range .Slider}}
<div class="home-slider flickity-dots-absolute" data-flickity='{ "bgLazyLoad": 1, "bgLazyLoad": true, "fade": true, "prevNextButtons": false, "autoPlay": 7000, "pauseAutoPlayOnHover": false }'>
<div class="home-slider-single-item" data-flickity-bg-lazyload="{{.Image}}">
<div class="container">
<div class="row d-flex align-items-center">
<div class="col">
<div class="home-slider-content">
<h1 class="home-slider-title">{{.title}}</h1>
<div class="home-slider-description">
<p>{{.description}}</p>
</div>
<div class="home-slider-btn-box">
<a class="button home-btn-1 mr-15" href="{{.button1_href}}">{{.button1_title}}</a>
<a class="button btn-primary" href="{{.button2_href}}">{{.button1_title}}</a>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
{{end}}
`
)

type ServiceSection struct {
Heading1 string `json:"Heading1"`
Heading2 string `json:"Heading2"`
Services []struct {
Image   string `json:"Image"`
Href    string `json:"Href"`
Heading string `json:"Heading"`
} `json:"Services"`
}

type SliderStruct struct {
Title        string `json:"title"`
Description  string `json:"description"`
Button1Title string `json:"button1_title"`
Button1Href  string `json:"button1_href"`
Button2Title string `json:"button2_title"`
Button2Href  string `json:"button2_href"`
Image        string `json:"Image"`
}

type SliderSection struct {
Slider []SliderStruct
}

type MyInterface interface {
populateHTML(string, string)
}

func (ss ServiceSection) populateHTML(endpoint string, tmpl string) {
populateHTMLcommon(ss, endpoint, tmpl)
}
func (ss SliderSection) populateHTML(endpoint string, tmpl string) {
populateHTMLcommon(ss, endpoint, tmpl)
}

func main() {
println("WASM Go Initialized")

ServiceSec := ServiceSection{}
SliderSec := SliderSection{}

ServiceSec.populateHTML(getServicesAPI, servicesTemplate)
SliderSec.populateHTML(getSliderAPI, sliderTemplate)

}

func populateHTMLcommon(hs MyInterface, endpoint string, tmplStr string) {
fmt.Println("struct ServiceSection", hs, endpoint)

// GET API CALL
fmt.Println("Inside getDataFromAPI()")

response, err := http.Get(endpoint)
if err != nil {
log.Fatal(err)
}

responseData, err := ioutil.ReadAll(response.Body)
if err != nil {
log.Fatal(err)
}

err = json.Unmarshal(responseData, &hs)
if err != nil {
log.Fatal(err)
}

// Create HTML using template
tmpl := template.Must(template.New("table").Parse(tmplStr))

buf := new(bytes.Buffer)              // Buffer created to hold the final HTML
err = tmpl.Execute(buf, responseData) // Populate the data in the HTML template
if err != nil {
log.Fatal(err)
}

tableHTMLString := buf.String()
fmt.Println("tableHTMLString: ", tableHTMLString)
}

在执行上述程序时，我在populateHTMLcommon((函数中得到以下错误，同时取消JSON-

json：无法将对象分解为main类型的Go值。MyInterface

这意味着它无法从MyInterface接口中识别适当的结构。

我不明白如何创建一个适用于多个结构的通用函数。感谢您的帮助。

Answer 1

两件事：

• Go接口是一种抽象，因此很少需要获取接口的地址
• 如果结构的方法需要更改结构的状态(并保持更改(，请使用指针接收器

因此，要解决您眼前的问题：

// err = json.Unmarshal(responseData, &hs) // address of an interface usually is not what you want
err = json.Unmarshal(responseData, hs)

并更新您的方法签名以使用指针接收器：

func (ss *ServiceSection) populateHTML(endpoint string, tmpl string) {
populateHTMLcommon(ss, endpoint, tmpl)
}
func (ss *SliderSection) populateHTML(endpoint string, tmpl string) {
populateHTMLcommon(ss, endpoint, tmpl)
}

https://play.golang.org/p/cGmm3Cs5XTk