Struct ZNull 

pub struct ZNull { /* private fields */ }

Schema that accepts only null. Created via vld::null().

Example

use vld::prelude::*;

assert_eq!(vld::null().parse("null").unwrap(), ());
assert!(vld::null().parse("0").is_err());

Implementations

impl ZNull

pub fn new() -> ZNull

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

pub fn type_error(self, msg: impl Into<String>) -> ZNull

Set a custom error message for non-null input.

Trait Implementations

impl Clone for ZNull

fn clone(&self) -> ZNull

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Default for ZNull

fn default() -> ZNull

Returns the “default value” for a type.

impl VldSchema for ZNull

type Output = ()

The Rust type produced by this schema after successful parsing.

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

Parse and validate a serde_json::Value.

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

Parse an object field whose key is absent.

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

where I: VldInput + ?Sized,

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

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

where T: Serialize,

Validate an existing Rust value against this schema.

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

where T: Serialize,

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

where S: VldSchema, 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>(self, other: B) -> ZUnion2<Self, B>

where B: VldSchema,

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

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

where B: VldSchema,

Create an intersection: input must satisfy both schemas.

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

Override the error message for this schema.