Enum ComparatorProperty 

#[non_exhaustive]
pub enum ComparatorProperty {
    ReceivedAt,
    Size,
    From,
    To,
    Subject,
    SentAt,
    HasKeyword,
    AllInThreadHaveKeyword,
    SomeInThreadHaveKeyword,
    Other(String),
}

The property to sort by in an EmailComparator (RFC 8621 §4.4.2).

When the variant is HasKeyword, AllInThreadHaveKeyword, or SomeInThreadHaveKeyword, the keyword field on EmailComparator MUST also be set (RFC 8621 §4.4.2).

Unknown property names from the server are preserved in Other so they round-trip correctly.

Excluded from extras preservation

This enum is out of scope for the workspace extras-preservation policy: it is a control enum that backends must dispatch on to determine the sort order, so a generic catch-all variant would be meaningless for query execution. The Other(String) variant that ComparatorProperty does carry exists only to preserve unknown property names for client-side round-tripping; servers cannot meaningfully sort by an unrecognised property without a registered extension.

More broadly, filter / comparator algebra is excluded because unrecognised clauses are a query-correctness hazard: silently dropping or round-tripping a clause the server does not understand can return the wrong set of records to the client without any error signal.

What to do instead

IETF-track path. Vendors who need both capability-level declaration and filterability for custom fields should use draft-ietf-jmap-metadata (capability URI urn:ietf:params:jmap:metadata), which defines a filterable Metadata / Annotation companion object. Implemented in jmap-metadata-types, jmap-metadata-server, and jmap-metadata-client (bd JMAP-06zp).

Pre-IETF escape. Vendors who cannot wait for the metadata draft can either escape to serde_json::Value or fork the per-crate FilterCondition / ComparatorProperty types. See crate-jmap-calendars-types/PLAN.md for the hybrid sloppy-value pattern.

Cross-reference: bd JMAP-lbdy “Decision: filter algebra excluded”.

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.

ReceivedAt

Sort by receivedAt.

Size

Sort by message size in octets.

From

Sort by the text of the From header field.

To

Sort by the text of the To header field.

Subject

Sort by the decoded Subject.

SentAt

Sort by sentAt.

HasKeyword

Sort by whether Emails in the Thread have the given keyword.

AllInThreadHaveKeyword

Sort by whether all Emails in the Thread have the given keyword.

SomeInThreadHaveKeyword

Sort by whether some Emails in the Thread have the given keyword.

Other(String)

A server-extension property name not listed above.

Trait Implementations

impl Clone for ComparatorProperty

fn clone(&self) -> ComparatorProperty

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for ComparatorProperty

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for ComparatorProperty

fn deserialize<D: Deserializer<'de>>(d: D) -> Result<Self, D::Error>

Deserialize this value from the given Serde deserializer.

impl Display for ComparatorProperty

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

Formats the value using the given formatter.

impl Eq for ComparatorProperty

impl Hash for ComparatorProperty

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for ComparatorProperty

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

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Serialize for ComparatorProperty

fn serialize<S: Serializer>(&self, s: S) -> Result<S::Ok, S::Error>

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for ComparatorProperty