Struct ScalarField 

pub struct ScalarField { /* private fields */ }

One scalar question in a questionnaire.

The id is the stable machine identity rendered as the line-terminal tag (<id:project.name>); the prompt is human wording and may be edited freely without affecting compatibility. Everything else — kind, optionality, default (static value or dynamic-default revision), constraint, condition, and validator revision — is semantic.

Implementations

impl ScalarField

pub fn new( id: impl Into<String>, prompt: impl Into<String>, kind: ScalarKind, ) -> Self

Create a required scalar field with a stable id, human prompt wording, and answer kind.

The id and all declared properties are validated when the field is passed to Questionnaire::new, not here.

pub fn optional(self) -> Self

Mark this field as optional (a blank answer without a default means omission rather than a missing-value error).

Optionality is semantic: it changes the fingerprint.

pub fn with_default(self, default: impl Into<String>) -> Self

Declare a static default value.

The renderer pre-fills the default as the answer text below the question line, and during decoding any blank answer resolves to the default before optionality is considered. Defaults must be a single line with no outer whitespace (parsed answers are trimmed) and must themselves decode cleanly. Defaults are semantic: they change the fingerprint. A field declares either a static default or a dynamic one, never both.

pub fn with_dynamic_default(self, dynamic_default: DynamicDefault) -> Self

Declare a dynamic default, computed from earlier decoded answers.

The same blank rule applies as for a static default — a blank answer resolves through the computed default before optionality, identically across interactive, file, and stdin collection — but the rendered sheet leaves the answer region empty (a sheet cannot pre-fill a value that depends on other answers), and interactive prompting shows the computed default in the prompt message. The declared revision is semantic and enters the fingerprint in place of a static value; see DynamicDefault for the revision and dependency contracts. A field declares either a static default or a dynamic one, never both.

pub fn one_of( self, choices: impl IntoIterator<Item = impl Into<String>>, ) -> Self

Constrain the answer to one of the given values.

Checked after kind conversion by the shared decoder. Not applicable to ScalarKind::Bool fields. Semantic: changes the fingerprint.

pub fn active_when( self, controller: impl Into<String>, expected: impl Into<String>, ) -> Self

Make this field applicable only when the earlier-declared controller field decodes to expected.

The controller must live in the same group as this field or in one of its enclosing groups (so every submitted occurrence resolves it unambiguously); a controller inside a repeatable group gates its dependents per occurrence. An inactive field may stay blank (or keep its untouched pre-filled default) even when required; a populated inactive field is a validation error. Conditions are semantic: they change the fingerprint.

pub fn with_validator(self, validator: FieldValidator) -> Self

Attach an application validator with an explicit semantic revision.

See FieldValidator for the revision contract.

pub fn id(&self) -> &str

The stable field ID.

pub fn prompt(&self) -> &str

The human wording (cosmetic).

pub fn kind(&self) -> ScalarKind

The answer kind (semantic).

pub fn is_optional(&self) -> bool

Whether a blank answer without a default means omission rather than a missing value.

pub fn default(&self) -> Option<&str>

The declared static default, if any (semantic).

pub fn dynamic_default(&self) -> Option<&DynamicDefault>

The declared dynamic default, if any (its revision is semantic).

pub fn constraint(&self) -> Option<&Constraint>

The declared constraint, if any (semantic).

pub fn condition(&self) -> Option<&Condition>

The conditional-applicability rule, if any (semantic).

pub fn validator(&self) -> Option<&FieldValidator>

The attached application validator, if any (its revision is semantic).

Trait Implementations

impl Clone for ScalarField

fn clone(&self) -> ScalarField

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for ScalarField

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

Formats the value using the given formatter.

impl Eq for ScalarField

impl From<ScalarField> for Item

fn from(field: ScalarField) -> Self

Converts to this type from the input type.

impl PartialEq for ScalarField

fn eq(&self, other: &ScalarField) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for ScalarField