pflagstruct

Warning

Update, June 2024: This repo and tool are no longer maintained. Please see github.com/cloud104/pflagstruct for a maintained fork instead.

A code generation tool that simplifies the process of registering command line flags in Go applications

Installation

To install you need to have Go installed and set up on your machine. Then, you can use the following command to install the tool:

go install github.com/totvs-cloud/pflagstruct@latest

Usage

The CLI provides the following flags:

• --destination string: Specifies the path where the generated code will be saved. If not provided, the current path is used.
• --directory string: Specifies the path where the source file containing the struct definition is located. This flag is required if --package is not informed.
• --package string: Specifies the package path of the struct definition. This flag is required if --directory is not informed.
• --struct-name string: Specifies the name of the struct. This flag is required.

Examples

1. Generate code using a struct definition in a directory:

   pflagstruct --directory /path/to/source --struct-name MyStruct

2. Generate code using a struct definition in a package:

   pflagstruct --package github.com/example/package --struct-name MyStruct

3. Generate code with a custom destination path:

   pflagstruct --destination /path/to/destination --package github.com/example/package --struct-name MyStruct

4. Automate the code generation process using the //go:generate comment in your Go source files:

   //go:generate pflagstruct --struct-name=User --package=github.com/example/model
   
   package main
   
   import (
       "context"
   
       "github.com/spf13/cobra"
       "github.com/example/client"
   )
   
   func NewCommand() *cobra.Command {
       cmd := &cobra.Command{
           Use:   "create",
           Short: "Create a new user.",
           RunE: func(cmd *cobra.Command, args []string) error {
               // Get user from command flags
               user, err := GetUserFromFlags(cmd.Flags()) // generated method
               if err != nil {
                   return err
               }
   
               // Create a new user
               return client.CreateUser(user)
           },
       }
       SetUpUserToFlags(cmd.Flags()) // generated method
   
       return cmd
   }

   For the referenced struct, as shown below:

   package model
   
   type User struct {
       // Unique identifier of the user.
       ID string
       // Name of the user.
       Name string
       // Email address of the user.
       Email string
   }

   The generated code appears as follows:

   package main
   
   import (
       "fmt"
       "github.com/spf13/pflag"
       "github.com/example/model"
   )
   
   func SetUpUserToFlags(flags *pflag.FlagSet) {
       (&userFlagsBuilder{flags: flags}).setUpUser()
   }
   
   func GetUserFromFlags(flags *pflag.FlagSet) (*model.User, error) {
       return (&userFlagsBuilder{flags: flags}).getUser()
   }
   
   type userFlagsBuilder struct { flags *pflag.FlagSet }
   
   func (cf *userFlagsBuilder) setUpUser() {
       cf.flags.String("id", "", "Unique identifier of the user.")
       cf.flags.String("name", "", "Name of the user.")
       cf.flags.String("email", "", "Email address of the user.")
   }
   
   func (cf *userFlagsBuilder) getUser() (user *model.User, err error) {
       user = new(model.User)
       if user.ID, err = cf.flags.GetString("id"); err != nil {
           return nil, fmt.Errorf("error retrieving \"id\" from command flags: %w", err)
       }
       if user.Name, err = cf.flags.GetString("name"); err != nil {
           return nil, fmt.Errorf("error retrieving \"name\" from command flags: %w", err)
       }
       if user.Email, err = cf.flags.GetString("email"); err != nil {
           return nil, fmt.Errorf("error retrieving \"email\" from command flags: %w", err)
       }
       return user, nil
   }

Feel free to explore the available flags and experiment with different options to generate code based on your struct definitions.

Contributing

Contributions to the pflagstruct are welcome! If you find any issues or have suggestions for improvement, please open an issue or submit a pull request.