使用Golang变量的文本模板

我正在尝试使用 text/template 动态生成类似 ini 的配置，其中原始数据以 yaml 格式提供。

我希望结果输出根据请求的来源而有所不同。

请考虑以下损坏的代码：

package main

import (
    "fmt"
    "gopkg.in/yaml.v3"
    "os"
    "text/template"
)

var yamldata = `
# comment
---
states:
- statename: california
  dateestablished: september 9, 1850
  cities:
  - cityname: los angeles
    population: 4 million
  - cityname: santa barbara
    population: 92 thousand
  - cityname: san jose
    population: 1 million
- statename: washington
  dateestablished: november 11, 1889
  cities:
  - cityname: seattle
    population: 724 thousand
    climate: wet
  - cityname: spokane
    population: 217 thousand
    climate: dry
  - cityname: scappoose
    population: 7
`

const reporttemplate string = `{{ range . }}
# {{ if .cityname == requestingcityname }}
# {{ .cityname }}
[requestingcity]
population = {{ .population }}
{{ if .climate }}climate = {{ .climate }}{{ end }}
{{ end }}
# {{ if .cityname != requestingcityname }}
# {{ .cityname }}
[city]
population = {{ .population }}
{{ if .climate }}climate = {{ .climate }}{{ end }}
{{ end }}
{{ end }}
`

type datastruct struct {
    states []struct {
        statename       string `yaml:"statename"`
        dateestablished string `yaml:"dateestablished"`
        cities          []struct {
            cityname   string `yaml:"cityname"`
            population string `yaml:"population"`
            climate    string `yaml:"climate,omitempty"`
        } `yaml:"cities"`
    } `yaml:"states"`
}

func (d *datastruct) readdata(data []byte) *datastruct {
    yaml.unmarshal(data, d)
    return d
}

func main() {

    var report datastruct
    report.readdata([]byte(yamldata))
    t := template.must(template.new("new").parse(reporttemplate))

    requestingstatename := "washington"
    requestingcityname := "seattle"

    for i := range report.states {
        if report.states[i].statename == requestingstatename {
            x := report.states[i].cities
            fmt.println(t.execute(os.stdout, x))

        }
    }
}

大部分代码都按照我期望的方式“工作”，但我遇到问题的部分是如何制作模板。

我希望能够更改 requestingcityname 的值，以便输出将像这样更改：

如果 requestingcityname == "scappoose" 那么输出将如下所示：

# scappoose
[requestingcity]
population = 7

# spokane
[city]
population = 217 thousand
climate = dry

# seattle
[city]
population = 724 thousand
climate = wet

或者如果 requestingcityname == "西雅图" 那么输出将如下所示：

# Seattle
[RequestingCity]
Population = 724 Thousand
Climate = wet

# Spokane
[City]
Population = 217 Thousand
Climate = dry

# Scappoose
[City]
Population = 7

如何制作模板以便我能够实现所需的行为？

解决方案

一个简单的解决方案是将不同的数据对象传递给 template.execute。像这样的东西：

type templateData struct {
    requestingCityName string
    cities             []citiesStruct // or whatever you name the struct
}
...
fmt.Println(t.Execute(os.Stdout, templateData{requestingCityName, x}))

此解决方案需要您更新模板以使用新的上下文结构（即旧的城市数组现在是 .cities 而不是 .），但它允许您访问 .requestingcityname。 p>