Trait apache_avro::schema::derive::AvroSchemaComponent
source · pub trait AvroSchemaComponent {
// Required method
fn get_schema_in_ctxt(
named_schemas: &mut HashMap<Name, Schema>,
enclosing_namespace: &Namespace,
) -> Schema;
}Expand description
Trait for types that serve as fully defined components inside an Avro data model. Derive
implementation available through derive feature. This is what is implemented by
the derive(AvroSchema) macro.
§Implementation guide
§Simple implementation
To construct a non named simple schema, it is possible to ignore the input argument making the general form implementation look like
ⓘ
impl AvroSchemaComponent for AType {
fn get_schema_in_ctxt(_: &mut Names, _: &Namespace) -> Schema {
Schema::?
}
}§Passthrough implementation
To construct a schema for a Type that acts as in “inner” type, such as for smart pointers, simply pass through the arguments to the inner type
ⓘ
impl AvroSchemaComponent for PassthroughType {
fn get_schema_in_ctxt(named_schemas: &mut Names, enclosing_namespace: &Namespace) -> Schema {
InnerType::get_schema_in_ctxt(names, enclosing_namespace)
}
}§Complex implementation
To implement this for Named schema there is a general form needed to avoid creating invalid schemas or infinite loops.
ⓘ
impl AvroSchemaComponent for ComplexType {
fn get_schema_in_ctxt(named_schemas: &mut Names, enclosing_namespace: &Namespace) -> Schema {
// Create the fully qualified name for your type given the enclosing namespace
let name = apache_avro::schema::Name::new("MyName")
.expect("Unable to parse schema name")
.fully_qualified_name(enclosing_namespace);
let enclosing_namespace = &name.namespace;
// Check, if your name is already defined, and if so, return a ref to that name
if named_schemas.contains_key(&name) {
apache_avro::schema::Schema::Ref{name: name.clone()}
} else {
named_schemas.insert(name.clone(), apache_avro::schema::Schema::Ref{name: name.clone()});
// YOUR SCHEMA DEFINITION HERE with the name equivalent to "MyName".
// For non-simple sub types delegate to their implementation of AvroSchemaComponent
}
}
}Required Methods§
fn get_schema_in_ctxt( named_schemas: &mut HashMap<Name, Schema>, enclosing_namespace: &Namespace, ) -> Schema
Object Safety§
This trait is not object safe.