CLI Prompting

When you write your own lemmego run … command, you sometimes need to ask the person running it a question — which database to target, whether to really delete something, a name for the thing being generated.

The cmder package gives you those prompts: a line of text, a yes/no, a multiple choice, a hidden password field. It is the same toolkit lemmego new uses to ask you about your project.

Basic prompts

Ask

import "github.com/lemmego/api/cmder"

name := cmder.Ask("What is your name?", nil).Result

With validation:

name := cmder.Ask("Enter your email", func(input string) error {
    if !strings.Contains(input, "@") {
        return fmt.Errorf("invalid email")
    }
    return nil
}).Result

Confirm

confirmed := cmder.Confirm("Continue?", 'y')
if confirmed.Confirmed {
    // proceed
}

Select

selected := cmder.Select("Choose a color", []cmder.Item{
    {Label: "Red"},
    {Label: "Green"},
    {Label: "Blue"},
})

MultiSelect

selected := cmder.MultiSelect("Select toppings", []cmder.Item{
    {Label: "Cheese", IsSelected: true},
    {Label: "Pepperoni"},
    {Label: "Mushrooms"},
}, 0) // 0 = position of "Done" item

Chaining Prompts

Prompts can be chained with conditional execution:

result := cmder.
    Ask("Project name?", nil).
    Confirm("Include Redis?", 'y').
    When(true, cmder.Ask("Redis host:", nil))

Use in CLI Commands

The prompting utilities are used extensively in the CLI’s code generators:

// From the interactive model generator
name := cmder.Ask("Field name (snake_case):", validateSnakeCase).Result
fieldType := cmder.Select("Field type:", fieldTypes)

Result Types

type PromptResult struct {
    Result    string
    Confirmed bool
    Items     []Item
}

Interrupt Handling

All prompts handle Ctrl+C gracefully, exiting the application cleanly.

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