@oneOf input objects (#1062, #1055, #1347)

Makefile

@@ -138,6 +138,7 @@ endif
 
 book.build:
 	mdbook build book/ $(if $(call eq,$(out),),,-d $(out))
+	rm -rf $(or $(out),book/_rendered)/lib.rs
 
 
 # Spellcheck Book.

book/src/types/enums.md

@@ -70,7 +70,7 @@ enum Episode {
 #
 # fn main() {}
 ```
-> **TIP**: Supported policies are: `SCREAMING_SNAKE_CASE`, `camelCase` and `none` (disables any renaming).
+> **TIP**: Supported policies are: `SCREAMING_SNAKE_CASE`, `snake_case`, `camelCase` and `none` (disables any renaming).
 
 
 ### Documentation and deprecation

book/src/types/input_objects.md

@@ -14,7 +14,7 @@ In [Juniper], defining a [GraphQL input object][0] is quite straightforward and
 #[derive(GraphQLInputObject)]
 struct Coordinate {
     latitude: f64,
-    longitude: f64
+    longitude: f64,
 }
 
 struct Root;
@@ -32,27 +32,48 @@ impl Root {
 # fn main() {}
 ```
 
+[`@oneOf`] [input objects][0] could be defined by using the [`#[derive(GraphQLInputObject)]` attribute][2] on a [Rust enum][enum]:
+```rust
+# #![expect(unused_variables, reason = "example")]
+# extern crate juniper;
+# use juniper::{GraphQLInputObject, ID};
+#
+#[derive(GraphQLInputObject)]
+enum UserBy {
+    Id(ID),       // Every `enum` variant declares a `Null`able input object field,
+    Name(String), // so there is no need to use `Option<String>` explicitly.
+}
+#
+# fn main() {}
+```
+
 
 ### Renaming
 
-Just as with [defining GraphQL objects](objects/index.md#renaming), by default [struct] fields are converted from [Rust]'s standard `snake_case` naming convention into [GraphQL]'s `camelCase` convention:
+Just as with [defining GraphQL objects](objects/index.md#renaming), by default [struct] fields (or [enum] variants) are converted from [Rust]'s standard naming convention into [GraphQL]'s `camelCase` convention:
 ```rust
 # extern crate juniper;
-# use juniper::GraphQLInputObject;
+# use juniper::{GraphQLInputObject, ID};
 #
 #[derive(GraphQLInputObject)]
 struct Person {
     first_name: String, // exposed as `firstName` in GraphQL schema
     last_name: String,  // exposed as `lastName` in GraphQL schema
 }
+
+#[derive(GraphQLInputObject)]
+enum UserBy {
+    Id(ID),       // exposed as `id` in GraphQL schema
+    Name(String), // exposed as `name` in GraphQL schema
+}
 #
 # fn main() {}
 ```
 
 We can override the name by using the `#[graphql(name = "...")]` attribute:
 ```rust
 # extern crate juniper;
-# use juniper::GraphQLInputObject;
+# use juniper::{GraphQLInputObject, ID};
 #
 #[derive(GraphQLInputObject)]
 #[graphql(name = "WebPerson")] // now exposed as `WebPerson` in GraphQL schema
@@ -62,14 +83,22 @@ struct Person {
     #[graphql(name = "websiteURL")]
     website_url: Option<String>, // now exposed as `websiteURL` in GraphQL schema
 }
+
+#[derive(GraphQLInputObject)]
+#[graphql(name = "By")] // now exposed as `By` in GraphQL schema
+enum UserBy {
+    #[graphql(name = "ID")]
+    Id(ID),       // now exposed as `ID` in GraphQL schema
+    Name(String), 
+}
 #
 # fn main() {}
 ```
 
 Or provide a different renaming policy for all the [struct] fields:
 ```rust
 # extern crate juniper;
-# use juniper::GraphQLInputObject;
+# use juniper::{GraphQLInputObject, ID};
 #
 #[derive(GraphQLInputObject)]
 #[graphql(rename_all = "none")] // disables any renaming
@@ -78,18 +107,25 @@ struct Person {
     age: i32,
     website_url: Option<String>, // exposed as `website_url` in GraphQL schema
 }
+
+#[derive(GraphQLInputObject)]
+#[graphql(rename_all = "none")] // disables any renaming
+enum UserBy {
+    Id(ID),       // exposed as `Id` in GraphQL schema
+    Name(String), // exposed as `Name` in GraphQL schema
+}
 #
 # fn main() {}
 ```
-> **TIP**: Supported policies are: `SCREAMING_SNAKE_CASE`, `camelCase` and `none` (disables any renaming).
+> **TIP**: Supported policies are: `SCREAMING_SNAKE_CASE`, `snake_case`, `camelCase` and `none` (disables any renaming).
 
 
 ### Documentation and deprecation
 
 Similarly, [GraphQL input fields][1] may also be [documented][7] and [deprecated][9] via `#[graphql(description = "...")]` and `#[graphql(deprecated = "...")]`/[`#[deprecated]`][13] attributes:
 ```rust
 # extern crate juniper;
-# use juniper::GraphQLInputObject;
+# use juniper::{GraphQLInputObject, ID};
 #
 /// This doc comment is visible only in Rust API docs.
 #[derive(GraphQLInputObject)]
@@ -112,6 +148,28 @@ struct Person {
     #[deprecated]
     another: Option<f64>, // has no description in GraphQL schema
 }
+
+/// This doc comment is visible only in Rust API docs.
+#[derive(GraphQLInputObject)]
+#[graphql(description = "This description is visible only in GraphQL schema.")]
+enum UserBy {
+    /// This doc comment is visible only in Rust API docs.
+    #[graphql(desc = "This description is visible only in GraphQL schema.")]
+    //        ^^^^ shortcut for a `description` argument
+    Id(ID),
+
+    /// This doc comment is visible in both Rust API docs and GraphQL schema 
+    /// descriptions.
+    // `enum` variants represent `Null`able input fields already, so can be naturally
+    // deprecated without any default values.
+    #[graphql(deprecated = "Just because.")]
+    Name(String),
+
+    // If no explicit deprecation reason is provided,
+    // then the default "No longer supported" one is used.
+    #[deprecated]
+    Bio(String), // has no description in GraphQL schema
+}
 #
 # fn main() {}
 ```
@@ -120,11 +178,11 @@ struct Person {
 
 ### Ignoring
 
-By default, all [struct] fields are included into the generated [GraphQL input object][0] type. To prevent inclusion of a specific field annotate it with the `#[graphql(ignore)]` attribute:
+By default, all [struct] fields (or [enum] variants) are included into the generated [GraphQL input object][0] type. To prevent inclusion of a specific field/variant annotate it with the `#[graphql(ignore)]` attribute:
 > **WARNING**: Ignored fields must either implement `Default` or be annotated with the `#[graphql(default = <expression>)]` argument.
 ```rust
 # extern crate juniper;
-# use juniper::GraphQLInputObject;
+# use juniper::{GraphQLInputObject, ID};
 #
 enum System {
     Cartesian,
@@ -146,6 +204,15 @@ struct Point2D {
     //        ^^^^ alternative naming, up to your preference
     shift: f64, 
 }
+
+#[derive(GraphQLInputObject)]
+enum UserBy {
+    Id(ID),
+    // Ignored `enum` variants naturally doesn't require `Default` implementation or
+    // `default` value being specified, as they're just never constructed from an input.
+    #[graphql(ignore)]
+    Name(String),
+}
 #
 # fn main() {}
 ```
@@ -154,6 +221,9 @@ struct Point2D {
 
 
 
+
+[`@oneOf`]: https://spec.graphql.org/September2025#sec--oneOf
+[enum]: https://doc.rust-lang.org/stable/reference/items/enumerations.html
 [GraphQL]: https://graphql.org
 [Juniper]: https://docs.rs/juniper
 [Rust]: https://www.rust-lang.org

book/src/types/interfaces.md

@@ -312,7 +312,7 @@ trait Person {
 #
 # fn main() {}
 ```
-> **TIP**: Supported policies are: `SCREAMING_SNAKE_CASE`, `camelCase` and `none` (disables any renaming).
+> **TIP**: Supported policies are: `SCREAMING_SNAKE_CASE`, `snake_case`, `camelCase` and `none` (disables any renaming).
 
 
 ### Documentation and deprecation

book/src/types/objects/complex_fields.md

@@ -111,7 +111,7 @@ impl Person {
 #
 # fn main() {}
 ```
-> **TIP**: Supported policies are: `SCREAMING_SNAKE_CASE`, `camelCase` and `none` (disables any renaming).
+> **TIP**: Supported policies are: `SCREAMING_SNAKE_CASE`, `snake_case`, `camelCase` and `none` (disables any renaming).
 
 
 ### Documentation and deprecation

book/src/types/objects/index.md

@@ -123,7 +123,7 @@ struct Person {
 #
 # fn main() {}
 ```
-> **TIP**: Supported policies are: `SCREAMING_SNAKE_CASE`, `camelCase` and `none` (disables any renaming).
+> **TIP**: Supported policies are: `SCREAMING_SNAKE_CASE`, `snake_case`, `camelCase` and `none` (disables any renaming).
 
 
 ### Deprecation

juniper/CHANGELOG.md

@@ -24,7 +24,11 @@ All user visible changes to `juniper` crate will be documented in this file. Thi
 ### Added
 
 - [September 2025] GraphQL spec: ([#1347])
-    - `__Type.isOneOf` field. ([#1348], [graphql/graphql-spec#825])
+    - `@oneOf` input objects: ([#1354], [#1062], [#1055], [graphql/graphql-spec#825])
+        - `@oneOf` built-in directive.
+        - `__Type.isOneOf` field. ([#1348])
+        - `schema::meta::InputObjectMeta::is_one_of` field.
+        - `enum`s support to `#[derive(GraphQLInputObject)]` macro.
     - `SCHEMA`, `OBJECT`, `ARGUMENT_DEFINITION`, `INTERFACE`, `UNION`, `ENUM`, `INPUT_OBJECT` and `INPUT_FIELD_DEFINITION` values to `__DirectiveLocation` enum. ([#1348])
     - Arguments and input object fields deprecation: ([#1348], [#864], [graphql/graphql-spec#525], [graphql/graphql-spec#805])
         - Placing `#[graphql(deprecated)]` and `#[deprecated]` attributes on struct fields in `#[derive(GraphQLInputObject)]` macro.
@@ -37,6 +41,7 @@ All user visible changes to `juniper` crate will be documented in this file. Thi
     - Full Unicode range support. ([#1349], [graphql/graphql-spec#849], [graphql/graphql-spec#687])
     - Support parsing descriptions on operations, fragments and variable definitions. ([#1349], [graphql/graphql-spec#1170])
 - Support for [block strings][0180-1]. ([#1349])
+- Support of `#[graphql(rename_all = "snake_case")]` attribute in macros. ([#1354])
 
 ### Changed
 
@@ -50,10 +55,13 @@ All user visible changes to `juniper` crate will be documented in this file. Thi
 - Incorrect double escaping in `ScalarToken::String` `Display`ing. ([#1349])
 
 [#864]: /../../issues/864
+[#1055]: /../../issues/1055
+[#1062]: /../../issues/1062
 [#1347]: /../../issues/1347
 [#1348]: /../../pull/1348
 [#1349]: /../../pull/1349
 [#1353]: /../../pull/1353
+[#1354]: /../../pull/1354
 [graphql/graphql-spec#525]: https://github.com/graphql/graphql-spec/pull/525
 [graphql/graphql-spec#687]: https://github.com/graphql/graphql-spec/issues/687
 [graphql/graphql-spec#805]: https://github.com/graphql/graphql-spec/pull/805

juniper/src/schema/meta.rs

@@ -348,6 +348,8 @@ pub struct InputObjectMeta<S> {
     pub description: Option<ArcStr>,
     #[doc(hidden)]
     pub input_fields: Vec<Argument<S>>,
+    #[doc(hidden)]
+    pub is_one_of: bool,
     #[debug(ignore)]
     pub(crate) try_parse_fn: InputValueParseFn<S>,
 }
@@ -364,6 +366,7 @@ impl<S> InputObjectMeta<S> {
             name: name.into(),
             description: None,
             input_fields: input_fields.to_vec(),
+            is_one_of: false,
             try_parse_fn: try_parse_fn::<S, T>,
         }
     }
@@ -377,6 +380,15 @@ impl<S> InputObjectMeta<S> {
         self
     }
 
+    /// Marks this [`InputObjectMeta`] type as [`@oneOf`].
+    ///
+    /// [`@oneOf`]: https://spec.graphql.org/September2025#sec--oneOf
+    #[must_use]
+    pub fn one_of(mut self) -> Self {
+        self.is_one_of = true;
+        self
+    }
+
     /// Wraps this [`InputObjectMeta`] type into a generic [`MetaType`].
     pub fn into_meta(self) -> MetaType<S> {
         MetaType::InputObject(self)

juniper/src/schema/model.rs

@@ -250,14 +250,16 @@ impl<S> SchemaType<S> {
 
         registry.get_type::<SchemaType<S>>(&());
 
+        let deprecated_directive = DirectiveType::new_deprecated(&mut registry);
         let include_directive = DirectiveType::new_include(&mut registry);
+        let one_of_directive = DirectiveType::new_one_of();
         let skip_directive = DirectiveType::new_skip(&mut registry);
-        let deprecated_directive = DirectiveType::new_deprecated(&mut registry);
         let specified_by_directive = DirectiveType::new_specified_by(&mut registry);
         directives.insert(include_directive.name.clone(), include_directive);
         directives.insert(skip_directive.name.clone(), skip_directive);
         directives.insert(deprecated_directive.name.clone(), deprecated_directive);
         directives.insert(specified_by_directive.name.clone(), specified_by_directive);
+        directives.insert(one_of_directive.name.clone(), one_of_directive);
 
         let mut meta_fields = vec![
             registry.field::<SchemaType<S>>(arcstr::literal!("__schema"), &()),
@@ -585,28 +587,33 @@ impl<S> DirectiveType<S> {
         }
     }
 
-    fn new_include(registry: &mut Registry<S>) -> Self
+    fn new_deprecated(registry: &mut Registry<S>) -> Self
     where
         S: ScalarValue,
     {
         Self::new(
-            arcstr::literal!("include"),
+            arcstr::literal!("deprecated"),
             &[
-                DirectiveLocation::Field,
-                DirectiveLocation::FragmentSpread,
-                DirectiveLocation::InlineFragment,
+                DirectiveLocation::FieldDefinition,
+                DirectiveLocation::ArgumentDefinition,
+                DirectiveLocation::InputFieldDefinition,
+                DirectiveLocation::EnumValue,
             ],
-            &[registry.arg::<bool>(arcstr::literal!("if"), &())],
+            &[registry.arg_with_default::<String>(
+                arcstr::literal!("reason"),
+                &"No longer supported".into(),
+                &(),
+            )],
             false,
         )
     }
 
-    fn new_skip(registry: &mut Registry<S>) -> Self
+    fn new_include(registry: &mut Registry<S>) -> Self
     where
         S: ScalarValue,
     {
         Self::new(
-            arcstr::literal!("skip"),
+            arcstr::literal!("include"),
             &[
                 DirectiveLocation::Field,
                 DirectiveLocation::FragmentSpread,
@@ -617,23 +624,30 @@ impl<S> DirectiveType<S> {
         )
     }
 
-    fn new_deprecated(registry: &mut Registry<S>) -> Self
+    fn new_one_of() -> Self
     where
         S: ScalarValue,
     {
         Self::new(
-            arcstr::literal!("deprecated"),
+            arcstr::literal!("oneOf"),
+            &[DirectiveLocation::InputObject],
+            &[],
+            false,
+        )
+    }
+
+    fn new_skip(registry: &mut Registry<S>) -> Self
+    where
+        S: ScalarValue,
+    {
+        Self::new(
+            arcstr::literal!("skip"),
             &[
-                DirectiveLocation::FieldDefinition,
-                DirectiveLocation::ArgumentDefinition,
-                DirectiveLocation::InputFieldDefinition,
-                DirectiveLocation::EnumValue,
+                DirectiveLocation::Field,
+                DirectiveLocation::FragmentSpread,
+                DirectiveLocation::InlineFragment,
             ],
-            &[registry.arg_with_default::<String>(
-                arcstr::literal!("reason"),
-                &"No longer supported".into(),
-                &(),
-            )],
+            &[registry.arg::<bool>(arcstr::literal!("if"), &())],
             false,
         )
     }