Struct Relation 

pub struct Relation {
    pub source: String,
    pub target: String,
    pub kind: RelationKind,
    pub field: Option<String>,
    pub target_data_model: Option<String>,
    pub is_builtin: bool,
}

A directed edge between two resource-types in (or out of) a data-model.

Two kinds: a link relation (a link field on the source resource-type points to the target; the field name labels the relation — field is Some) and an inheritance relation (the source extends the target as a superclass — field is None). Carries a target_data_model tag for cross-data-model targets (mirroring Field.data_model in the target direction) and an is_builtin flag whose meaning is asymmetric by kind (see below).

Invariants (asserted in unit tests; not enforced structurally — same precedent as Field.link_target in resource_type.rs):

• (a) field.is_some() iff kind == RelationKind::Link.
• (b) target_data_model == None whenever the target is in a system namespace (knora-api, knora-base, etc.).

No serde derive: wire deserialization stays in src/client/http.rs. See ADR-0001 / ADR-0008 and the CONTEXT.md “Relation” entry.

Fields

source: String

Source resource-type local name (IRI fragment, e.g. letter).

target: String

Target resource-type or superclass local name (IRI fragment, e.g. person or writtenSource).

kind: RelationKind

Whether this is a link relation or an inheritance relation.

field: Option<String>

The link-field local name that labels this relation (e.g. hasSender). Some iff kind == RelationKind::Link; None for inheritance relations. This invariant is asserted in unit tests — the type does not enforce it structurally.

target_data_model: Option<String>

The target resource-type’s data-model name (the CURIE prefix of the target’s @id). None when the target’s prefix is a system namespace (knora-api, knora-base, etc.); Some(prefix) otherwise. The renderer emits [to <dm>] iff Some(x) and x != DataModelStructure.data_model. Mirrors Field.data_model (which tags the source direction for cross-data-model fields). This invariant is asserted in unit tests.

is_builtin: bool

Builtin flag — semantics are asymmetric by kind:

• Link → true iff the link field’s CURIE prefix is a system namespace. A project-defined link field pointing to a built-in target is false (shown by default), because the field is project-defined.
• Inherits → true iff the superclass (target) CURIE prefix is a system namespace (e.g. Resource, StillImageRepresentation).

The action filters !r.is_builtin by default; --include-builtins shows all.

Trait Implementations

impl Clone for Relation

fn clone(&self) -> Relation

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Relation

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

Formats the value using the given formatter.

impl Eq for Relation

impl PartialEq for Relation

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for Relation