Support serde deny_unknown_fields (#816)

utoipa-gen/Cargo.toml

@@ -23,7 +23,7 @@ ulid = { version = "1", optional = true, default-features = false }
 url = { version = "2", optional = true }
 
 [dev-dependencies]
-utoipa = { path = "../utoipa", features = ["uuid"], default-features = false }
+utoipa = { path = "../utoipa", features = ["debug", "uuid"], default-features = false }
 serde_json = "1"
 serde = "1"
 actix-web = { version = "4", features = ["macros"], default-features = false }

utoipa-gen/src/component/schema.rs

@@ -473,7 +473,7 @@ impl ToTokens for NamedStructSchema<'_> {
             })
             .collect();
 
-        if !flatten_fields.is_empty() {
+        let all_of = if !flatten_fields.is_empty() {
             let mut flattened_tokens = TokenStream::new();
             let mut flattened_map_field = None;
             for field in flatten_fields {
@@ -504,16 +504,30 @@ impl ToTokens for NamedStructSchema<'_> {
             }
 
             if flattened_tokens.is_empty() {
-                tokens.extend(object_tokens)
+                tokens.extend(object_tokens);
+                false
             } else {
                 tokens.extend(quote! {
                     utoipa::openapi::AllOfBuilder::new()
                         #flattened_tokens
                     .item(#object_tokens)
-                })
+                });
+                true
             }
         } else {
-            tokens.extend(object_tokens)
+            tokens.extend(object_tokens);
+            false
+        };
+
+        if !all_of
+            && container_rules
+                .as_ref()
+                .and_then(|container_rule| Some(container_rule.deny_unknown_fields))
+                .unwrap_or(false)
+        {
+            tokens.extend(quote! {
+                .additional_properties(Some(utoipa::openapi::schema::AdditionalProperties::FreeForm(false)))
+            });
         }
 
         if let Some(deprecated) = super::get_deprecated(self.attributes) {

utoipa-gen/src/component/serde.rs

@@ -24,6 +24,7 @@ fn parse_next_lit_str(next: Cursor) -> Option<(String, Span)> {
 
 #[derive(Default)]
 #[cfg_attr(feature = "debug", derive(Debug))]
+#[cfg_attr(test, derive(PartialEq, Eq))]
 pub struct SerdeValue {
     pub skip: bool,
     pub rename: Option<String>,
@@ -89,6 +90,7 @@ impl SerdeValue {
 /// The default case (when no serde attributes are present) is `ExternallyTagged`.
 #[derive(Clone)]
 #[cfg_attr(feature = "debug", derive(Debug))]
+#[cfg_attr(test, derive(PartialEq, Eq))]
 pub enum SerdeEnumRepr {
     ExternallyTagged,
     InternallyTagged {
@@ -116,10 +118,12 @@ impl Default for SerdeEnumRepr {
 /// Attributes defined within a `#[serde(...)]` container attribute.
 #[derive(Default)]
 #[cfg_attr(feature = "debug", derive(Debug))]
+#[cfg_attr(test, derive(PartialEq, Eq))]
 pub struct SerdeContainer {
     pub rename_all: Option<RenameRule>,
     pub enum_repr: SerdeEnumRepr,
     pub default: bool,
+    pub deny_unknown_fields: bool,
 }
 
 impl SerdeContainer {
@@ -129,6 +133,7 @@ impl SerdeContainer {
     ///     * `content = ...`
     ///     * `untagged = ...`
     ///     * `default = ...`
+    ///     * `deny_unknown_fields`
     fn parse_attribute(&mut self, ident: Ident, next: Cursor) -> syn::Result<()> {
         match ident.to_string().as_str() {
             "rename_all" => {
@@ -188,6 +193,9 @@ impl SerdeContainer {
             "default" => {
                 self.default = true;
             }
+            "deny_unknown_fields" => {
+                self.deny_unknown_fields = true;
+            }
             _ => {}
         }
         Ok(())
@@ -262,6 +270,9 @@ pub fn parse_container(attributes: &[Attribute]) -> Option<SerdeContainer> {
                 if value.default {
                     acc.default = value.default;
                 }
+                if value.deny_unknown_fields {
+                    acc.deny_unknown_fields = value.deny_unknown_fields;
+                }
                 match value.enum_repr {
                     SerdeEnumRepr::ExternallyTagged => {}
                     SerdeEnumRepr::Untagged
@@ -282,6 +293,7 @@ pub fn parse_container(attributes: &[Attribute]) -> Option<SerdeContainer> {
 
 #[derive(Clone)]
 #[cfg_attr(feature = "debug", derive(Debug))]
+#[cfg_attr(test, derive(PartialEq, Eq))]
 pub enum RenameRule {
     Lower,
     Upper,
@@ -395,7 +407,8 @@ impl FromStr for RenameRule {
 
 #[cfg(test)]
 mod tests {
-    use super::{RenameRule, RENAME_RULE_NAME_MAPPING};
+    use super::{parse_container, RenameRule, SerdeContainer, RENAME_RULE_NAME_MAPPING};
+    use syn::{parse_quote, Attribute};
 
     macro_rules! test_rename_rule {
         ( $($case:expr=> $value:literal = $expected:literal)* ) => {
@@ -467,4 +480,35 @@ mod tests {
             s.parse::<RenameRule>().unwrap();
         }
     }
+
+    #[test]
+    fn test_serde_parse_container() {
+        let default_attribute_1: syn::Attribute = parse_quote! {
+            #[serde(default)]
+        };
+        let default_attribute_2: syn::Attribute = parse_quote! {
+            #[serde(default)]
+        };
+        let deny_unknown_fields_attribute: syn::Attribute = parse_quote! {
+            #[serde(deny_unknown_fields)]
+        };
+        let unsupported_attribute: syn::Attribute = parse_quote! {
+            #[serde(expecting = "...")]
+        };
+        let attributes: &[Attribute] = &[
+            default_attribute_1,
+            default_attribute_2,
+            deny_unknown_fields_attribute,
+            unsupported_attribute,
+        ];
+
+        let expected = SerdeContainer {
+            default: true,
+            deny_unknown_fields: true,
+            ..Default::default()
+        };
+
+        let result = parse_container(attributes).unwrap();
+        assert_eq!(expected, result);
+    }
 }

utoipa-gen/src/lib.rs

@@ -238,6 +238,7 @@ use self::{
 /// * `untagged` Supported at the container level. Allows [untagged
 /// enum representation](https://serde.rs/enum-representations.html#untagged).
 /// * `default` Supported at the container level and field level according to [serde attributes].
+/// * `deny_unknown_fields` Supported at the container level.
 /// * `flatten` Supported at the field level.
 ///
 /// Other _`serde`_ attributes works as is but does not have any effect on the generated OpenAPI doc.

utoipa-gen/tests/schema_derive_test.rs

@@ -3771,6 +3771,31 @@ fn derive_schema_with_default_struct() {
     )
 }
 
+#[test]
+fn derive_struct_with_no_additional_properties() {
+    let value = api_doc! {
+        #[derive(serde::Deserialize, Default)]
+        #[serde(deny_unknown_fields)]
+        struct MyValue {
+            field: String
+        }
+    };
+
+    assert_json_eq!(
+        value,
+        json!({
+            "properties": {
+                "field": {
+                    "type": "string",
+                }
+            },
+            "required": ["field"],
+            "additionalProperties": false,
+            "type": "object"
+        })
+    )
+}
+
 #[test]
 #[cfg(feature = "repr")]
 fn derive_schema_for_repr_enum() {