feat(dojo-core): add read schema support

crates/dojo/core-cairo-test/src/tests/model/model.cairo

@@ -36,12 +36,39 @@ struct Foo3 {
     v2: u32,
 }
 
+#[derive(Copy, Drop, Serde, Debug, Introspect)]
+struct AStruct {
+    a: u8,
+    b: u8,
+    c: u8,
+    d: u8,
+}
+
+#[dojo::model]
+#[derive(Copy, Drop, Serde, Debug)]
+struct Foo4 {
+    #[key]
+    id: felt252,
+    v0: u256,
+    v1: felt252,
+    v2: u128,
+    v3: AStruct,
+}
+
+#[derive(Copy, Drop, Serde, Debug, Introspect)]
+struct FooSchema {
+    v0: u256,
+    v3: AStruct,
+}
+
 fn namespace_def() -> NamespaceDef {
     NamespaceDef {
         namespace: "dojo_cairo_test",
         resources: [
             TestResource::Model(m_Foo::TEST_CLASS_HASH.try_into().unwrap()),
             TestResource::Model(m_Foo2::TEST_CLASS_HASH.try_into().unwrap()),
+            TestResource::Model(m_Foo3::TEST_CLASS_HASH.try_into().unwrap()),
+            TestResource::Model(m_Foo4::TEST_CLASS_HASH.try_into().unwrap()),
         ]
             .span(),
     }
@@ -268,3 +295,48 @@ fn test_ptrs_from() {
     let ptrs_d = Model::<Foo>::ptrs_from_ids([foo.entity_id(), foo2.entity_id()].span());
     assert!(ptrs_a == ptrs_b && ptrs_a == ptrs_c && ptrs_a == ptrs_d);
 }
+
+#[test]
+fn test_read_schema() {
+    let mut world = spawn_foo_world();
+    let foo = Foo4 { id: 1, v0: 2, v1: 3, v2: 4, v3: AStruct { a: 5, b: 6, c: 7, d: 8 } };
+    world.write_model(@foo);
+
+    let schema: FooSchema = world.read_schema(foo.ptr());
+    assert!(
+        schema.v0 == foo.v0
+            && schema.v3.a == foo.v3.a
+            && schema.v3.b == foo.v3.b
+            && schema.v3.c == foo.v3.c
+            && schema.v3.d == foo.v3.d,
+    );
+}
+
+#[test]
+fn test_read_schemas() {
+    let mut world = spawn_foo_world();
+    let foo = Foo4 { id: 1, v0: 2, v1: 3, v2: 4, v3: AStruct { a: 5, b: 6, c: 7, d: 8 } };
+    let mut foo_2 = foo;
+    foo_2.id = 2;
+    foo_2.v0 = 12;
+
+    world.write_models([@foo, @foo_2].span());
+
+    let mut values: Array<FooSchema> = world.read_schemas([foo.ptr(), foo_2.ptr()].span());
+    let schema_1 = values.pop_front().unwrap();
+    let schema_2 = values.pop_front().unwrap();
+    assert!(
+        schema_1.v0 == foo.v0
+            && schema_1.v3.a == foo.v3.a
+            && schema_1.v3.b == foo.v3.b
+            && schema_1.v3.c == foo.v3.c
+            && schema_1.v3.d == foo.v3.d,
+    );
+    assert!(
+        schema_2.v0 == foo_2.v0
+            && schema_2.v3.a == foo_2.v3.a
+            && schema_2.v3.b == foo_2.v3.b
+            && schema_2.v3.c == foo_2.v3.c
+            && schema_2.v3.d == foo_2.v3.d,
+    );
+}

crates/dojo/core/src/model/model.cairo

@@ -12,6 +12,14 @@ pub struct ModelPtr<M> {
     pub id: felt252,
 }
 
+/// Trait that defines a method for converting a span of model pointers to a span of model indexes.
+///
+/// # Type Parameters
+/// - `M`: The type of the model.
+///
+/// # Methods
+/// - `to_indexes(self: Span<ModelPtr<M>>) -> Span<ModelIndex>`:
+///   Converts the span of model pointers to a span of model indexes.
 pub trait ModelPtrsTrait<M> {
     fn to_indexes(self: Span<ModelPtr<M>>) -> Span<ModelIndex>;
     fn to_member_indexes(self: Span<ModelPtr<M>>, field_selector: felt252) -> Span<ModelIndex>;

crates/dojo/core/src/model/storage.cairo

@@ -1,4 +1,4 @@
-use dojo::{model::{ModelPtr, model_value::ModelValueKey}};
+use dojo::{model::{ModelPtr, model_value::ModelValueKey}, meta::Introspect};
 
 // TODO: define the right interface for member accesses.
 
@@ -53,6 +53,14 @@ pub trait ModelStorage<S, M> {
         ref self: S, ptrs: Span<ModelPtr<M>>, field_selector: felt252, values: Span<T>,
     );
 
+    /// Retrieves a subset of members in a model, matching a defined schema <T>.
+    fn read_schema<T, +Serde<T>, +Introspect<T>>(self: @S, ptr: ModelPtr<M>) -> T;
+
+    /// Retrieves part of multiple models, matching a schema.
+    fn read_schemas<T, +Drop<T>, +Serde<T>, +Introspect<T>>(
+        self: @S, ptrs: Span<ModelPtr<M>>,
+    ) -> Array<T>;
+
     /// Returns the current namespace hash.
     fn namespace_hash(self: @S) -> felt252;
 }

crates/dojo/core/src/world/storage.cairo

@@ -6,7 +6,7 @@ use dojo::model::{
     Model, ModelIndex, ModelValueKey, ModelValue, ModelStorage, ModelPtr, ModelPtrsTrait,
 };
 use dojo::event::{Event, EventStorage};
-use dojo::meta::Layout;
+use dojo::meta::{Layout, FieldLayout, Introspect};
 use dojo::utils::{
     entity_id_from_keys, entity_id_from_serialized_keys, serialize_inline, find_model_field_layout,
     deserialize_unwrap,
@@ -26,6 +26,17 @@ fn field_layout_unwrap<M, +Model<M>>(field_selector: felt252) -> Layout {
     }
 }
 
+fn make_partial_struct_layout<M, +Model<M>>(field_selectors: Span<felt252>) -> Layout {
+    let mut layouts: Array<FieldLayout> = array![];
+    for selector in field_selectors {
+        layouts
+            .append(
+                FieldLayout { selector: *selector, layout: field_layout_unwrap::<M>(*selector) },
+            );
+    };
+    Layout::Struct(layouts.span())
+}
+
 #[generate_trait]
 pub impl WorldStorageInternalImpl of WorldStorageTrait {
     fn new(world: IWorldDispatcher, namespace: @ByteArray) -> WorldStorage {
@@ -267,6 +278,33 @@ pub impl ModelStorageWorldStorageImpl<M, +Model<M>, +Drop<M>> of ModelStorage<Wo
         );
     }
 
+    fn read_schema<T, +Serde<T>, +Introspect<T>>(self: @WorldStorage, ptr: ModelPtr<M>) -> T {
+        deserialize_unwrap(
+            IWorldDispatcherTrait::entity(
+                *self.dispatcher,
+                Model::<M>::selector(*self.namespace_hash),
+                ModelIndex::Id(ptr.id),
+                Introspect::<T>::layout(),
+            ),
+        )
+    }
+
+    fn read_schemas<T, +Drop<T>, +Serde<T>, +Introspect<T>>(
+        self: @WorldStorage, ptrs: Span<ModelPtr<M>>,
+    ) -> Array<T> {
+        let mut values = ArrayTrait::<T>::new();
+
+        for entity in IWorldDispatcherTrait::entities(
+            *self.dispatcher,
+            Model::<M>::selector(*self.namespace_hash),
+            ptrs.to_indexes(),
+            Introspect::<T>::layout(),
+        ) {
+            values.append(deserialize_unwrap(*entity));
+        };
+        values
+    }
+
     fn namespace_hash(self: @WorldStorage) -> felt252 {
         *self.namespace_hash
     }

examples/benchmark/Scarb.lock

@@ -0,0 +1,28 @@
+# Code generated by scarb DO NOT EDIT.
+version = 1
+
+[[package]]
+name = "dojo"
+version = "1.0.12"
+dependencies = [
+ "dojo_plugin",
+]
+
+[[package]]
+name = "dojo_benchmark"
+version = "0.1.0"
+dependencies = [
+ "dojo",
+ "dojo_cairo_test",
+]
+
+[[package]]
+name = "dojo_cairo_test"
+version = "1.0.12"
+dependencies = [
+ "dojo",
+]
+
+[[package]]
+name = "dojo_plugin"
+version = "2.9.2"

examples/benchmark/Scarb.toml

@@ -0,0 +1,23 @@
+[package]
+cairo-version = "=2.9.2"
+name = "dojo_benchmark"
+version = "0.1.0"
+edition = "2024_07"
+
+[[target.starknet-contract]]
+sierra = true
+casm = true
+build-external-contracts = ["dojo::world::world_contract::world"]
+
+[dependencies]
+dojo = { path = "../../crates/dojo/core" }
+starknet = "2.9.2"
+
+[dev-dependencies]
+cairo_test = "2.9.2"
+dojo_cairo_test = { path = "../../crates/dojo/core-cairo-test" }
+
+[features]
+default = []
+
+[profile.sepolia]

examples/benchmark/dojo_dev.toml

@@ -0,0 +1,4 @@
+[world]
+description = "Simple world."
+name = "simple"
+seed = "simple"