How to Generate a Customized Bash Script Using Go Templates, Switch-Case Statements, and YAML Data?

Golang Template with Switch & ForEach

Problem: Construct a bash script from a Golang program that iterates over a list of dependencies, checks their types, and prints customized commands based on those types using switch-case statements.

Answer:

The following updated Golang code accomplishes the desired behavior:

<code class="go">package main

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

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

type Dependency struct {
    Name    string
    Type    string
}

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 "runner1":
    echo "Submitting api1"
  case "runner2":
    echo "Submitting api2"
  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:

• The code uses text/template to format the output string.
• The range keyword iterates over the Dependency array.
• Inside the loop, a switch-case block is used to customize the output based on the Type of the dependency.
• The case statements handle specific Type values and print the desired commands.
• The default case handles types that are not specifically defined.

Result:

The example bash script produced by this code is:

<code class="bash">#!/bin/bash

echo "type is runner"
Submitting api1


echo "type is runner2"
Submitting api2</code>

Additional Considerations:

• The example YAML data is hard-coded in the data variable. In a real-world scenario, this could be loaded from a file or database.
• The API mapping (from Type to command) could be implemented as a map or separate configuration file for improved flexibility.
• The cwd and Install fields in the Dependency struct are unused in this solution, as they were not required for the demo.

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