Enum Rule 

#[non_exhaustive]
pub enum Rule {
    Required,
    RequiredOn(Mode),
    MinLength(usize),
    MaxLength(usize),
    Email,
    Numeric,
    Url,
    Date,
    Unique,
}

A single rule applied to one field’s submitted value. Serde-serialisable so a descriptor (later YAML) can author rules by name (required, email, max_length, …).

Non-exhaustive: rules are added as field types need them, so match with a _ arm.

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

Required

Non-empty after trimming, in every mode.

RequiredOn(Mode)

Non-empty after trimming, in the given mode only.

MinLength(usize)

At least n characters. Skipped when empty, so pair it with Required to forbid blanks.

MaxLength(usize)

At most n characters.

Email

A syntactically plausible email address. Skipped when empty.

Numeric

Parses as a number (integer or decimal). Skipped when empty.

Url

A syntactically valid absolute URL with a host. Skipped when empty.

Date

A calendar date, YYYY-MM-DD. Skipped when empty.

Unique

The value must not already exist in this field’s column of the target table. On update, the edited row is ignored.

Trait Implementations

impl Clone for Rule

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Rule

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for Rule

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Serialize for Rule

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.