fix: tagged enum with flatten fields

utoipa-gen/CHANGELOG.md

@@ -1,5 +1,11 @@
 # Changelog - utoipa-gen
 
+## Unreleased
+
+### Fixed
+
+* Fix tagged enum with flatten fields (https://github.com/juhaku/utoipa/pull/1208)
+
 ## 5.2.0 - Nov 2024
 
 ### Fixed
@@ -454,7 +460,7 @@
 * Add support for multiple examples in response (https://github.com/juhaku/utoipa/pull/403)
 * Add Example type to OpenApi types (https://github.com/juhaku/utoipa/pull/402)
 * Add derive info support for derive OpenApi (https://github.com/juhaku/utoipa/pull/400)
-* Add `merge` functionality for `OpenApi` (https://github.com/juhaku/utoipa/pull/397) 
+* Add `merge` functionality for `OpenApi` (https://github.com/juhaku/utoipa/pull/397)
 * Add derive servers attribute for OpenApi (https://github.com/juhaku/utoipa/pull/395)
 * Add support for unit sructs (https://github.com/juhaku/utoipa/pull/392)
 * Add support for `schema_with` custom fn reference (https://github.com/juhaku/utoipa/pull/390)

utoipa-gen/src/component/schema.rs

@@ -313,6 +313,7 @@ pub struct NamedStructSchema {
     pub schema_as: Option<As>,
     fields_references: Vec<SchemaReference>,
     bound: Option<Bound>,
+    is_all_of: bool,
 }
 
 #[cfg_attr(feature = "debug", derive(Debug))]
@@ -385,6 +386,7 @@ impl NamedStructSchema {
             .flatten()
             .collect::<Vec<_>>();
 
+        let mut object_tokens_empty = true;
         let object_tokens = fields_vec
             .iter()
             .filter(|(_, field_rules, ..)| !field_rules.skip && !field_rules.flatten)
@@ -415,6 +417,7 @@ impl NamedStructSchema {
                     _field,
                     field_schema,
                 )| {
+                    object_tokens_empty = false;
                     let rename_to = field_rules
                         .rename
                         .as_deref()
@@ -513,8 +516,13 @@ impl NamedStructSchema {
                 tokens.extend(quote! {
                     utoipa::openapi::AllOfBuilder::new()
                         #flattened_tokens
-                    .item(#object_tokens)
+
                 });
+                if !object_tokens_empty {
+                    tokens.extend(quote! {
+                        .item(#object_tokens)
+                    });
+                }
                 true
             }
         } else {
@@ -552,6 +560,7 @@ impl NamedStructSchema {
             schema_as,
             fields_references,
             bound,
+            is_all_of: all_of,
         })
     }
 

utoipa-gen/src/component/schema/enums.rs

@@ -517,12 +517,26 @@ impl MixedEnumContent {
                     MixedEnumContent::split_enum_features(variant_features);
                 let schema = NamedStructSchema::new(root, fields, variant_features)?;
 
-                let schema_tokens = schema.to_token_stream();
+                let mut schema_tokens = schema.to_token_stream();
                 (
-                    EnumSchema::<ObjectSchema>::tagged(schema_tokens)
-                        .tag(tag, PlainSchema::for_name(name.as_ref()))
-                        .features(enum_features)
-                        .to_token_stream(),
+                    if schema.is_all_of {
+                        let object_builder_tokens =
+                            quote! { utoipa::openapi::schema::Object::builder() };
+                        let enum_schema_tokens =
+                            EnumSchema::<ObjectSchema>::tagged(object_builder_tokens)
+                                .tag(tag, PlainSchema::for_name(name.as_ref()))
+                                .features(enum_features)
+                                .to_token_stream();
+                        schema_tokens.extend(quote! {
+                            .item(#enum_schema_tokens)
+                        });
+                        schema_tokens
+                    } else {
+                        EnumSchema::<ObjectSchema>::tagged(schema_tokens)
+                            .tag(tag, PlainSchema::for_name(name.as_ref()))
+                            .features(enum_features)
+                            .to_token_stream()
+                    },
                     schema.fields_references,
                 )
             }

utoipa-gen/tests/schema_derive_test.rs

@@ -1089,6 +1089,55 @@ fn derive_simple_enum_serde_tag() {
     );
 }
 
+#[test]
+fn derive_simple_enum_serde_tag_with_flatten_content() {
+    #[derive(Serialize, ToSchema)]
+    #[allow(unused)]
+    struct Foo {
+        name: &'static str,
+    }
+
+    let value: Value = api_doc! {
+        #[derive(Serialize)]
+        #[serde(tag = "tag")]
+        enum Bar {
+            One {
+                #[serde(flatten)]
+                foo: Foo,
+            },
+        }
+    };
+
+    assert_json_eq!(
+        value,
+        json!({
+            "oneOf": [
+                {
+                    "allOf": [
+                        {
+                            "$ref": "#/components/schemas/Foo",
+                        },
+                         {
+                            "type": "object",
+                            "properties":  {
+                                "tag":  {
+                                    "type": "string",
+                                    "enum":  [
+                                        "One",
+                                    ],
+                                },
+                            },
+                            "required":  [
+                                "tag",
+                            ],
+                        },
+                    ],
+                },
+            ],
+        })
+    );
+}
+
 #[test]
 fn derive_simple_enum_serde_untagged() {
     let value: Value = api_doc! {