Add support for enums of integers in rust-server generator.

modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/RustServerCodegen.java

@@ -386,7 +386,7 @@ public String toParamName(String name) {
 
     @Override
     public String toEnumValue(String value, String datatype) {
-        // rust-server templates expect value to be in quotes
+        // rust-server templates expect value to be in quotes for Display/FromStr
         return "\"" + super.toEnumValue(value, datatype) + "\"";
     }
 
@@ -1565,6 +1565,31 @@ public void postProcessModelProperty(CodegenModel model, CodegenProperty propert
     public ModelsMap postProcessModels(ModelsMap objs) {
         ModelsMap result = super.postProcessModelsEnum(objs);
 
+        // Fix for integer enums: add unquoted numeric values for serde serialization.
+        // Integer enums should serialize as JSON numbers, not strings.
+        for (ModelMap modelMap : result.getModels()) {
+            CodegenModel model = modelMap.getModel();
+
+            if (Boolean.TRUE.equals(model.isEnum) &&
+                (model.isInteger || model.isLong || model.isNumber) &&
+                model.allowableValues != null) {
+
+                @SuppressWarnings("unchecked")
+                List<Map<String, Object>> enumVars =
+                    (List<Map<String, Object>>) model.allowableValues.get("enumVars");
+
+                if (enumVars != null) {
+                    for (Map<String, Object> enumVar : enumVars) {
+                        String value = (String) enumVar.get("value");
+                        if (value != null) {
+                            // Strip quotes added by toEnumValue()
+                            enumVar.put("numericValue", value.substring(1, value.length() - 1));
+                        }
+                    }
+                }
+            }
+        }
+
         // Check for model names that conflict with serde_valid macro internals
         // Once we find one, set a class-level flag that persists across all model batches
         if (!hasConflictingModelNames) {

modules/openapi-generator/src/main/resources/rust-server/models.mustache

@@ -36,7 +36,12 @@ use crate::header;
 pub enum {{{classname}}} {
 {{#allowableValues}}
   {{#enumVars}}
+    {{#numericValue}}
+    #[serde(rename = {{{numericValue}}})]
+    {{/numericValue}}
+    {{^numericValue}}
     #[serde(rename = {{{value}}})]
+    {{/numericValue}}
     {{{name}}},
   {{/enumVars}}
 {{/allowableValues}}

samples/server/petstore/rust-server/output/petstore-with-fake-endpoints-models-for-testing/src/models.rs

@@ -3542,9 +3542,9 @@ impl EnumTest {
 #[cfg_attr(feature = "validate", derive(Validate))]
 #[cfg_attr(feature = "conversion", derive(frunk_enum_derive::LabelledGenericEnum))]
 pub enum EnumTestEnumInteger {
-    #[serde(rename = "1")]
+    #[serde(rename = 1)]
     Variant1,
-    #[serde(rename = "-1")]
+    #[serde(rename = -1)]
     Variant12,
 }
 
@@ -8464,9 +8464,9 @@ impl TestEnumParametersEnumQueryDoubleParameter {
 #[cfg_attr(feature = "validate", derive(Validate))]
 #[cfg_attr(feature = "conversion", derive(frunk_enum_derive::LabelledGenericEnum))]
 pub enum TestEnumParametersEnumQueryIntegerParameter {
-    #[serde(rename = "1")]
+    #[serde(rename = 1)]
     Variant1,
-    #[serde(rename = "-2")]
+    #[serde(rename = -2)]
     Variant2,
 }