Struct ZLazy 

pub struct ZLazy<T, F>
where
    F: Fn() -> T,
    T: VldSchema,
{ /* private fields */ }

Lazy schema for recursive/self-referencing data structures.

The schema factory is called on the first parse_value of this node and the result is cached, which allows defining schemas that reference themselves without rebuilding them on every parse.

Created via vld::lazy().

Every vld::lazy(...) node calls its factory once; nested lazy nodes built by the factory are themselves created on first use, so a recursive schema unfolds only as deep as the inputs go.

Example

// Recursive tree: { value: i64, children: Tree[] }
fn tree_schema() -> impl VldSchema<Output = serde_json::Map<String, serde_json::Value>> {
    vld::object()
        .field("value", vld::number().int())
        .field("children", vld::array(vld::lazy(tree_schema)))
}

Implementations

impl<T, F> ZLazy<T, F>

where F: Fn() -> T, T: VldSchema,

pub fn new(factory: F) -> Self

Create the schema (the same as its vld:: constructor function).

pub fn schema(&self) -> &T

The (cached) schema produced by the factory.

Trait Implementations

impl<T: VldSchema, F: Fn() -> T> CollectNestedSchemas for ZLazy<T, F>

Available on crate feature openapi only.

fn collect_nested_schemas(&self, _out: &mut Vec<NestedSchemaEntry>)

Add the named schemas this schema references to _out (for components.schemas).

impl<T: VldSchema, F: Fn() -> T> JsonSchema for ZLazy<T, F>

Available on crate feature openapi only.

{} — a recursive schema cannot be expanded inline.

fn json_schema(&self) -> Value

Generate a JSON Schema representation.

fn is_required(&self) -> bool

Whether this schema should be included in an object’s required array.

impl<T, F> VldSchema for ZLazy<T, F>

where F: Fn() -> T, T: VldSchema,

type Output = <T as VldSchema>::Output

The Rust type produced by this schema after successful parsing.

fn parse_value(&self, value: &Value) -> Result<T::Output, VldError>

Parse and validate a serde_json::Value.

fn parse_missing(&self) -> Result<T::Output, VldError>

Parse an object field whose key is absent.

fn parse<I: VldInput + ?Sized>( &self, input: &I, ) -> Result<Self::Output, VldError>

Parse from any supported input (JSON string, file path, serde_json::Value, etc.)

fn validate<T: Serialize>(&self, value: &T) -> Result<Self::Output, VldError>

Validate an existing Rust value against this schema.

fn is_valid<T: Serialize>(&self, value: &T) -> bool

Check if an existing Rust value passes this schema’s validation.

fn optional(self) -> ZOptional<Self>

Make this field optional. Missing or null values become None.

fn nullable(self) -> ZNullable<Self>

Allow null values. Null becomes None.

fn with_default(self, value: Self::Output) -> ZDefault<Self>

where Self::Output: Clone,

Provide a default value when the field is missing or null.

fn blank_as(self, value: Self::Output) -> ZDefault<Self>

where Self::Output: Clone,

Like with_default, and a blank string (empty or whitespace only) also becomes value: legacy stores that write "" or null for “unset”.

fn refine<F>(self, check: F, message: &str) -> ZRefine<Self, F>

where F: Fn(&Self::Output) -> bool,

Add a custom refinement check without changing the output type.

fn rule<R>(self, rule: R) -> ZRule<Self, R>

where Self: Sized, R: Rule<Self::Output>,

Check the output with a reusable Rule (output type unchanged).

fn rule_msg<R>(self, rule: R, msg: impl Into<String>) -> ZRule<Self, R>

where Self: Sized, R: Rule<Self::Output>,

rule with a custom error message.

fn try_transform<F, U, E>(self, f: F) -> ZTryTransform<Self, F, U>

where F: Fn(Self::Output) -> Result<U, E>, E: Display,

Transform the output with a fallible function; an Err becomes a validation issue (Custom { code: "transform" }, message = the error).

fn transform<F, U>(self, f: F) -> ZTransform<Self, F, U>

where F: Fn(Self::Output) -> U,

Transform the output value after successful parsing.

fn nullish(self) -> ZNullish<Self>

Make this field nullish (both optional and nullable).

fn catch(self, fallback: Self::Output) -> ZCatch<Self>

where Self::Output: Clone,

Return a fallback value on ANY validation error.

fn pipe<S: VldSchema>(self, next: S) -> ZPipe<Self, S>

where Self::Output: Serialize,

Chain this schema’s output into another schema.

fn describe(self, description: &str) -> ZDescribe<Self>

Attach a human-readable description/label to this schema.

fn super_refine<F>(self, check: F) -> ZSuperRefine<Self, F>

where F: Fn(&Self::Output, &mut VldError),

Add a custom refinement that can produce multiple errors.

fn or<B: VldSchema>(self, other: B) -> ZUnion2<Self, B>

Create a union: this schema or another. Returns Either<Self::Output, B::Output>.

fn and<B: VldSchema>(self, other: B) -> ZIntersection<Self, B>

Create an intersection: input must satisfy both schemas.

fn message(self, msg: impl Into<String>) -> ZMessage<Self>

Override the error message for this schema.