Struct bevy::reflect::serde::ReflectDeserializer

pub struct ReflectDeserializer<'a> { /* private fields */ }

A general purpose deserializer for reflected types.

This is the deserializer counterpart to ReflectSerializer.

See TypedReflectDeserializer for a deserializer that expects a known type.

Input

This deserializer expects a map with a single entry, where the key is the full type path of the reflected type and the value is the serialized data.

Output

This deserializer will return a Box<dyn Reflect> containing the deserialized data.

For value types (i.e. ReflectKind::Value) or types that register ReflectDeserialize type data, this Box will contain the expected type. For example, deserializing an i32 will return a Box<i32> (as a Box<dyn Reflect>).

Otherwise, this Box will contain the dynamic equivalent. For example, a deserialized struct might return a Box<DynamicStruct> and a deserialized Vec might return a Box<DynamicList>.

This means that if the actual type is needed, these dynamic representations will need to be converted to the concrete type using FromReflect or ReflectFromReflect.

Example

#[derive(Reflect, PartialEq, Debug)]
#[type_path = "my_crate"]
struct MyStruct {
  value: i32
}

let mut registry = TypeRegistry::default();
registry.register::<MyStruct>();

let input = r#"{
  "my_crate::MyStruct": (
    value: 123
  )
}"#;

let mut deserializer = ron::Deserializer::from_str(input).unwrap();
let reflect_deserializer = ReflectDeserializer::new(&registry);

let output: Box<dyn Reflect> = reflect_deserializer.deserialize(&mut deserializer).unwrap();

// Since `MyStruct` is not a value type and does not register `ReflectDeserialize`,
// we know that its deserialized representation will be a `DynamicStruct`.
assert!(output.is::<DynamicStruct>());
assert!(output.represents::<MyStruct>());

// We can convert back to `MyStruct` using `FromReflect`.
let value: MyStruct = <MyStruct as FromReflect>::from_reflect(&*output).unwrap();
assert_eq!(value, MyStruct { value: 123 });

// We can also do this dynamically with `ReflectFromReflect`.
let type_id = output.get_represented_type_info().unwrap().type_id();
let reflect_from_reflect = registry.get_type_data::<ReflectFromReflect>(type_id).unwrap();
let value: Box<dyn Reflect> = reflect_from_reflect.from_reflect(&*output).unwrap();
assert!(value.is::<MyStruct>());
assert_eq!(value.take::<MyStruct>().unwrap(), MyStruct { value: 123 });

Implementations

impl<'a> ReflectDeserializer<'a>

pub fn new(registry: &'a TypeRegistry) -> ReflectDeserializer<'a>

Examples found in repository

examples/reflection/reflection.rs (line 93)

fn setup(type_registry: Res<AppTypeRegistry>) {
    let mut value = Foo {
        a: 1,
        _ignored: NonReflectedValue { _a: 10 },
        nested: Bar { b: 8 },
    };

    // You can set field values like this. The type must match exactly or this will fail.
    *value.get_field_mut("a").unwrap() = 2usize;
    assert_eq!(value.a, 2);
    assert_eq!(*value.get_field::<usize>("a").unwrap(), 2);

    // You can also get the &dyn Reflect value of a field like this
    let field = value.field("a").unwrap();

    // you can downcast Reflect values like this:
    assert_eq!(*field.downcast_ref::<usize>().unwrap(), 2);

    // DynamicStruct also implements the `Struct` and `Reflect` traits.
    let mut patch = DynamicStruct::default();
    patch.insert("a", 4usize);

    // You can "apply" Reflect implementations on top of other Reflect implementations.
    // This will only set fields with the same name, and it will fail if the types don't match.
    // You can use this to "patch" your types with new values.
    value.apply(&patch);
    assert_eq!(value.a, 4);

    let type_registry = type_registry.read();
    // By default, all derived `Reflect` types can be Serialized using serde. No need to derive
    // Serialize!
    let serializer = ReflectSerializer::new(&value, &type_registry);
    let ron_string =
        ron::ser::to_string_pretty(&serializer, ron::ser::PrettyConfig::default()).unwrap();
    info!("{}\n", ron_string);

    // Dynamic properties can be deserialized
    let reflect_deserializer = ReflectDeserializer::new(&type_registry);
    let mut deserializer = ron::de::Deserializer::from_str(&ron_string).unwrap();
    let reflect_value = reflect_deserializer.deserialize(&mut deserializer).unwrap();

    // Deserializing returns a Box<dyn Reflect> value. Generally, deserializing a value will return
    // the "dynamic" variant of a type. For example, deserializing a struct will return the
    // DynamicStruct type. "Value types" will be deserialized as themselves.
    let _deserialized_struct = reflect_value.downcast_ref::<DynamicStruct>();

    // Reflect has its own `partial_eq` implementation, named `reflect_partial_eq`. This behaves
    // like normal `partial_eq`, but it treats "dynamic" and "non-dynamic" types the same. The
    // `Foo` struct and deserialized `DynamicStruct` are considered equal for this reason:
    assert!(reflect_value.reflect_partial_eq(&value).unwrap());

    // By "patching" `Foo` with the deserialized DynamicStruct, we can "Deserialize" Foo.
    // This means we can serialize and deserialize with a single `Reflect` derive!
    value.apply(&*reflect_value);
}

Trait Implementations

impl<'a, 'de> DeserializeSeed<'de> for ReflectDeserializer<'a>

type Value = Box<dyn Reflect>

The type produced by using this seed.

fn deserialize<D>( self, deserializer: D ) -> Result<<ReflectDeserializer<'a> as DeserializeSeed<'de>>::Value, <D as Deserializer<'de>>::Error>

where D: Deserializer<'de>,

Equivalent to the more common Deserialize::deserialize method, except with some initial piece of data (the seed) passed in.