Struct CustomType

pub struct CustomType<'a, T> {
    pub message: &'a str,
    pub default: Option<T>,
    pub placeholder: Option<&'a str>,
    pub help_message: Option<&'a str>,
    pub formatter: &'a dyn Fn(T) -> String,
    pub default_value_formatter: &'a dyn Fn(T) -> String,
    pub parser: &'a dyn Fn(&str) -> Result<T, ()>,
    pub validators: Vec<Box<dyn CustomTypeValidator<T>>>,
    pub error_message: String,
    pub render_config: RenderConfig,
}

Generic prompt suitable for when you need to parse the user input into a specific type, for example an f64 or a rust_decimal, maybe even an uuid.

This prompt has all of the validation, parsing and error handling features built-in to reduce as much boilerplaste as possible from your prompts. Its defaults are necessarily very simple in order to cover a large range of generic cases, for example a “Invalid input” error message.

You can customize as many aspects of this prompt as you like: prompt message, help message, default value, placeholder, value parser and value formatter.

Behavior

When initializing this prompt via the new() method, some constraints on the return type T are added to make sure we can apply a default parser and formatter to the prompt.

The default parser calls the str.parse method, which means that T must implement the FromStr trait. When the parsing fails for any reason, a default error message “Invalid input” is displayed to the user.

After the user submits, the prompt handler tries to parse the input into the expected type. If the operation succeeds, the value is returned to the prompt caller. If it fails, the message defined in error_message is displayed to the user.

The default formatter simply calls to_string() on the parsed value, which means that T must implement the ToString trait, which normally happens implicitly when you implement the Display trait.

If your type T does not satisfy these constraints, you can always manually instantiate the entire struct yourself like this:

use inquire::{CustomType, ui::RenderConfig};

let amount_prompt: CustomType<f64> = CustomType {
    message: "How much is your travel going to cost?",
    formatter: &|i| format!("${:.2}", i),
    default_value_formatter: &|i| format!("${:.2}", i),
    default: None,
    validators: vec![],
    placeholder: Some("123.45"),
    error_message: "Please type a valid number.".into(),
    help_message: "Do not use currency and the number should use dots as the decimal separator.".into(),
    parser: &|i| match i.parse::<f64>() {
        Ok(val) => Ok(val),
        Err(_) => Err(()),
    },
    render_config: RenderConfig::default(),
};

Example

use inquire::CustomType;

let amount = CustomType::<f64>::new("How much do you want to donate?")
    .with_formatter(&|i| format!("${:.2}", i))
    .with_error_message("Please type a valid number")
    .with_help_message("Type the amount in US dollars using a decimal point as a separator")
    .prompt();

match amount {
    Ok(_) => println!("Thanks a lot for donating that much money!"),
    Err(_) => println!("We could not process your donation"),
}

Fields

message: &'a str

Message to be presented to the user.

default: Option<T>

Default value, returned when the user input is empty.

placeholder: Option<&'a str>

Short hint that describes the expected value of the input.

help_message: Option<&'a str>

Help message to be presented to the user.

formatter: &'a dyn Fn(T) -> String

Function that formats the user input and presents it to the user as the final rendering of the prompt.

default_value_formatter: &'a dyn Fn(T) -> String

Function that formats the provided value. Useful for example when you want to format a default true to the string “Y/n”, common in confirmation prompts.

parser: &'a dyn Fn(&str) -> Result<T, ()>

Function that parses the user input and returns the result value.

validators: Vec<Box<dyn CustomTypeValidator<T>>>

Collection of validators to apply to the user input.

Validators are executed in the order they are stored, stopping at and displaying to the user only the first validation error that might appear.

The possible error is displayed to the user one line above the prompt.

error_message: String

Error message displayed when value could not be parsed from input.

render_config: RenderConfig

RenderConfig to apply to the rendered interface.

Note: The default render config considers if the NO_COLOR environment variable is set to decide whether to render the colored config or the empty one.

When overriding the config in a prompt, NO_COLOR is no longer considered and your config is treated as the only source of truth. If you want to customize colors and still suport NO_COLOR, you will have to do this on your end.

Implementations

impl<'a, T> CustomType<'a, T>

where T: Clone,

pub const DEFAULT_VALIDATORS: Vec<Box<dyn CustomTypeValidator<T>>>

Default validators added to the CustomType prompt, none.

pub fn new(message: &'a str) -> CustomType<'a, T>

where T: FromStr + ToString,

Creates a CustomType with the provided message and default configuration values.

pub fn with_default(self, default: T) -> CustomType<'a, T>

Sets the default input.

pub fn with_placeholder(self, placeholder: &'a str) -> CustomType<'a, T>

Sets the placeholder.

pub fn with_help_message(self, message: &'a str) -> CustomType<'a, T>

Sets the help message of the prompt.

pub fn with_formatter( self, formatter: &'a dyn Fn(T) -> String, ) -> CustomType<'a, T>

Sets the formatter

pub fn with_default_value_formatter( self, formatter: &'a dyn Fn(T) -> String, ) -> CustomType<'a, T>

Sets the formatter for default values.

Useful for example when you want to format a default true to the string “Y/n”, common in confirmation prompts, when the final answer would be displayed likely as “Yes” or “No”.

pub fn with_parser( self, parser: &'a dyn Fn(&str) -> Result<T, ()>, ) -> CustomType<'a, T>

Sets the parser.

pub fn with_validator<V>(self, validator: V) -> CustomType<'a, T>

where V: CustomTypeValidator<T> + 'static,

Adds a validator to the collection of validators. You might want to use this feature in case you need to require certain features from the parsed user’s answer.

Validators are executed in the order they are stored, stopping at and displaying to the user only the first validation error that might appear.

The possible error is displayed to the user one line above the prompt.

pub fn with_validators( self, validators: &[Box<dyn CustomTypeValidator<T>>], ) -> CustomType<'a, T>

Adds the validators to the collection of validators in the order they are given. You might want to use this feature in case you need to require certain features from the parsed user’s answer.

Validators are executed in the order they are stored, stopping at and displaying to the user only the first validation error that might appear.

The possible error is displayed to the user one line above the prompt.

pub fn with_error_message(self, error_message: &'a str) -> CustomType<'a, T>

Sets a custom error message displayed when a submission could not be parsed to a value.

pub fn with_render_config( self, render_config: RenderConfig, ) -> CustomType<'a, T>

Sets the provided color theme to this prompt.

Note: The default render config considers if the NO_COLOR environment variable is set to decide whether to render the colored config or the empty one.

When overriding the config in a prompt, NO_COLOR is no longer considered and your config is treated as the only source of truth. If you want to customize colors and still suport NO_COLOR, you will have to do this on your end.

pub fn prompt_skippable(self) -> Result<Option<T>, InquireError>

Parses the provided behavioral and rendering options and prompts the CLI user for input according to the defined rules.

This method is intended for flows where the user skipping/cancelling the prompt - by pressing ESC - is considered normal behavior. In this case, it does not return Err(InquireError::OperationCanceled), but Ok(None).

Meanwhile, if the user does submit an answer, the method wraps the return type with Some.

pub fn prompt(self) -> Result<T, InquireError>

Parses the provided behavioral and rendering options and prompts the CLI user for input according to the defined rules.

Trait Implementations

impl<'a, T> Clone for CustomType<'a, T>

where T: Clone,

fn clone(&self) -> CustomType<'a, T>

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<'a> From<Confirm<'a>> for CustomType<'a, bool>

fn from(co: Confirm<'a>) -> CustomType<'a, bool>

Converts to this type from the input type.