Add BRP method to mutate a component

crates/bevy_remote/src/builtin_methods.rs

@@ -17,8 +17,8 @@ use bevy_hierarchy::BuildChildren as _;
 use bevy_reflect::{
     prelude::ReflectDefault,
     serde::{ReflectSerializer, TypedReflectDeserializer},
-    NamedField, OpaqueInfo, PartialReflect, ReflectDeserialize, ReflectSerialize, TypeInfo,
-    TypeRegistration, TypeRegistry, VariantInfo,
+    GetPath as _, NamedField, OpaqueInfo, PartialReflect, ReflectDeserialize, ReflectSerialize,
+    TypeInfo, TypeRegistration, TypeRegistry, VariantInfo,
 };
 use bevy_utils::HashMap;
 use serde::{de::DeserializeSeed as _, Deserialize, Serialize};
@@ -50,6 +50,9 @@ pub const BRP_REPARENT_METHOD: &str = "bevy/reparent";
 /// The method path for a `bevy/list` request.
 pub const BRP_LIST_METHOD: &str = "bevy/list";
 
+/// The method path for a `bevy/reparent` request.
+pub const BRP_MUTATE_COMPONENT_METHOD: &str = "bevy/mutate_component";
+
 /// The method path for a `bevy/get+watch` request.
 pub const BRP_GET_AND_WATCH_METHOD: &str = "bevy/get+watch";
 
@@ -197,6 +200,28 @@ pub struct BrpListParams {
     pub entity: Entity,
 }
 
+/// `bevy/mutate`:
+///
+/// The server responds with a null.
+#[derive(Debug, Serialize, Deserialize, Clone, PartialEq)]
+pub struct BrpMutateParams {
+    /// The entity of the component to mutate.
+    pub entity: Entity,
+
+    /// The [full path] of component to mutate.
+    ///
+    /// [full path]: bevy_reflect::TypePath::type_path
+    pub component: String,
+
+    /// The [path] of the field within the component.
+    ///
+    /// [path]: bevy_reflect::GetPath
+    pub path: String,
+
+    /// The value to insert at `path`.
+    pub value: Value,
+}
+
 /// Describes the data that is to be fetched in a query.
 #[derive(Debug, Serialize, Deserialize, Clone, Default, PartialEq)]
 pub struct BrpQuery {
@@ -694,6 +719,70 @@ pub fn process_remote_insert_request(
     Ok(Value::Null)
 }
 
+/// Handles a `bevy/mutate_component` request coming from a client.
+///
+/// This method allows you to mutate a single field inside an Entity's
+/// component.
+pub fn process_remote_mutate_component_request(
+    In(params): In<Option<Value>>,
+    world: &mut World,
+) -> BrpResult {
+    let BrpMutateParams {
+        entity,
+        component,
+        path,
+        value,
+    } = parse_some(params)?;
+    let app_type_registry = world.resource::<AppTypeRegistry>().clone();
+    let type_registry = app_type_registry.read();
+
+    // Get the fully-qualified type names of the component to be mutated.
+    let component_type: &TypeRegistration = type_registry
+        .get_with_type_path(&component)
+        .ok_or_else(|| {
+            BrpError::component_error(anyhow!("Unknown component type: `{}`", component))
+        })?;
+
+    // Get the reflected representation of the component.
+    let mut reflected = component_type
+        .data::<ReflectComponent>()
+        .ok_or_else(|| {
+            BrpError::component_error(anyhow!("Component `{}` isn't registered.", component))
+        })?
+        .reflect_mut(world.entity_mut(entity))
+        .ok_or_else(|| {
+            BrpError::component_error(anyhow!("Cannot reflect component `{}`", component))
+        })?;
+
+    // Get the type of the field in the component that is to be
+    // mutated.
+    let value_type: &TypeRegistration = type_registry
+        .get_with_type_path(
+            reflected
+                .reflect_path(path.as_str())
+                .map_err(BrpError::component_error)?
+                .reflect_type_path(),
+        )
+        .ok_or_else(|| {
+            BrpError::component_error(anyhow!("Unknown component field type: `{}`", component))
+        })?;
+
+    // Get the reflected representation of the value to be inserted
+    // into the component.
+    let value: Box<dyn PartialReflect> = TypedReflectDeserializer::new(value_type, &type_registry)
+        .deserialize(&value)
+        .map_err(BrpError::component_error)?;
+
+    // Apply the mutation.
+    reflected
+        .reflect_path_mut(path.as_str())
+        .map_err(BrpError::component_error)?
+        .try_apply(value.as_ref())
+        .map_err(BrpError::component_error)?;
+
+    Ok(Value::Null)
+}
+
 /// Handles a `bevy/remove` request (remove components) coming from a client.
 pub fn process_remote_remove_request(
     In(params): In<Option<Value>>,

crates/bevy_remote/src/lib.rs

@@ -194,6 +194,19 @@
 //!
 //! `result`: null.
 //!
+//! ### `bevy/mutate_component`
+//!
+//! Mutate a field in a component.
+//!
+//! `params`:
+//! - `entity`: The ID of the entity to with the component to mutate.
+//! - `component`: The component's [fully-qualified type name].
+//! - `path`: The path of the field within the component. See
+//!   [`GetPath`](bevy_reflect::GetPath#syntax) for more information on formatting this string.
+//! - `value`: The value to insert at `path`.
+//!
+//! `result`: null.
+//!
 //! ### bevy/reparent
 //!
 //! Assign a new parent to one or more entities.
@@ -419,6 +432,10 @@ impl Default for RemotePlugin {
                 builtin_methods::BRP_REGISTRY_SCHEMA_METHOD,
                 builtin_methods::export_registry_types,
             )
+            .with_method(
+                builtin_methods::BRP_MUTATE_COMPONENT_METHOD,
+                builtin_methods::process_remote_mutate_component_request,
+            )
             .with_watching_method(
                 builtin_methods::BRP_GET_AND_WATCH_METHOD,
                 builtin_methods::process_remote_get_watching_request,