Struct FormField 

pub struct FormField {
    pub label: String,
    pub input: TextInputState,
    pub error: Option<String>,
    pub trigger: ValidateTrigger,
    /* private fields */
}

A single form field with a label, an input, and its own validators.

Attach validators with the chainable validate builder (multiple allowed); choose when they run with on_change / on_blur. Context::form_field runs them automatically per trigger.

Example

let field = FormField::new("Email")
    .placeholder("you@example.com")
    .validate(validators::required("required"))
    .validate(validators::email());

Fields

label: String

Field label shown above the input.

input: TextInputState

Text input state for this field.

error: Option<String>

Validation error shown below the input when present.

trigger: ValidateTrigger

When the field’s validators run. Defaults to ValidateTrigger::OnBlur.

Implementations

impl FormField

pub fn new(label: impl Into<String>) -> Self

Create a new form field with the given label.

pub fn placeholder(self, p: impl Into<String>) -> Self

Set placeholder text for this field’s input.

pub fn validate(self, f: impl Fn(&str) -> Result<(), String> + 'static) -> Self

Attach a validator closure (chainable; call multiple times to stack validators — the first failure becomes the field error).

The closure may capture state, unlike the deprecated positional FormValidator. Built-ins live in validators.

Example

let field = FormField::new("Name")
    .validate(validators::required("required"))
    .validate(validators::max_len(50, "too long"));

pub fn on_change(self) -> Self

Run this field’s validators on every change (each keystroke).

pub fn on_blur(self) -> Self

Run this field’s validators when it loses focus (the default).

pub fn manual(self) -> Self

Disable automatic validation; the app must call run_validators or FormState::validate_all explicitly.

pub fn validator_count(&self) -> usize

Number of validators attached to this field.

pub fn run_validators(&mut self) -> bool

Run this field’s validators now, setting error to the first failure (or clearing it on success).

Returns true when the field is valid.

Example

let mut field = FormField::new("Name").validate(validators::required("required"));
assert!(!field.run_validators()); // empty -> error
field.input.value = "Jane".into();
assert!(field.run_validators()); // non-empty -> ok

pub fn validate_async<F>(&mut self, future: F)

where F: Future<Output = Result<(), String>> + Send + 'static,

Available on crate feature async only.

Spawn an asynchronous validation of the current value, replacing any previously pending check.

The future runs on the ambient tokio runtime; its Result is surfaced as error once poll_async (called each frame by Context::form_field) sees it complete.

Requires the async feature.

Example

let value = field.input.value.clone();
field.validate_async(async move {
    // e.g. hit a "username taken?" endpoint
    if value == "taken" { Err("already taken".into()) } else { Ok(()) }
});

pub fn is_validating(&self) -> bool

Available on crate feature async only.

Whether an async validation is currently in flight.

Requires the async feature.

pub fn poll_async(&mut self) -> bool

Available on crate feature async only.

Poll the in-flight async validation (if any) without blocking.

When the future has resolved, its result is written to error and the pending slot is cleared. Returns true when a result was just applied this call.

Requires the async feature.

Trait Implementations

impl Debug for FormField

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for FormField

fn default() -> FormField

Returns the “default value” for a type.