How do you generate a Bash script with specific commands based on dependency types using Golang template, switch statement, and ForEach loop?

Bash Script Generation with Golang Template, Switch, and ForEach

Challenge

The goal is to create a Bash script from a Golang program. The script should iterate over dependencies, identify their types using a switch statement, and echo different commands based on the type.

Implementation

To achieve this, we can use Go templates, which provide a convenient way to generate text files from structured data. Here's a solution using templates with switch and ForEach:

<code class="go">package main

import (
    "log"
    "text/template"
    "gopkg.in/yaml.v2"
    "os"
)

type File struct {
    TypeVersion string        `yaml:"_type-version"`
    Dependency  []Dependency `yaml:"dependency"`
}

type Dependency struct {
    Name    string            `yaml:"name"`
    Type    string            `yaml:"type"`
    CWD     string            `yaml:"cwd"`
    Install map[string]string `yaml:"install"`
}

var data = `
_type-version: "1.0.0"
dependency:
  - name: ui
    type: runner
    cwd: /ui
    install:
       - name: api

  - name: ui2
    type: runner2
    cwd: /ui2
    install:
       - name: api2

`

func main() {
    f := File{}

    err := yaml.Unmarshal([]byte(data), &f)
    if err != nil {
        log.Fatalf("error: %v", err)
    }

    const t = `
#!/bin/bash

{{range .Dependency}}
echo "type is {{.Type}}"
{{switch .Type}}
    case "runner":
        echo "running command for runner"
    case "runner2":
        echo "running command for runner2"
    default:
        echo "unknown type"
{{end}}
{{end}}
`

    tt := template.Must(template.New("").Parse(t))
    err = tt.Execute(os.Stdout, f)
    if err != nil {
        log.Println("executing template:", err)
    }
}</code>

Explanation

1. We use a YAML file (data) to define the dependencies and their types.
2. We parse the YAML file into a File struct using yaml.Unmarshal.
3. We define a template (t) using text/template. The template includes a ForEach loop to iterate over dependencies and a switch statement to handle different types.
4. We parse the template using template.Parse and execute it using Execute with the File struct as input.
5. This generates the Bash script with the desired commands based on dependency types.

Output

Running the above program produces the following output:

#!/bin/bash

type is runner
running command for runner
type is runner2
running command for runner2

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