[rust] support discriminators on existing fields

Author: Thomas Ville

bin/configs/rust-reqwest-oneOf-discriminator.yaml

@@ -0,0 +1,8 @@
+generatorName: rust
+outputDir: samples/client/others/rust/reqwest/oneOf-discriminator
+library: reqwest
+inputSpec: modules/openapi-generator/src/test/resources/3_0/oneOfDiscriminator.yaml
+templateDir: modules/openapi-generator/src/main/resources/rust
+additionalProperties:
+  supportAsync: false
+  packageName: oneof-discriminator-reqwest

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

@@ -318,6 +318,20 @@ public CodegenModel fromModel(String name, Schema model) {
         return mdl;
     }
 
+    @Override
+    public Map<String, ModelsMap> postProcessAllModels(Map<String, ModelsMap> objs) {
+        // Collect all models into a single list
+        List<ModelMap> allModels = new ArrayList<>();
+        for (ModelsMap models : objs.values()) {
+            allModels.addAll(models.getModels());
+        }
+
+        // Process oneOf discriminators across all models
+        postProcessOneOfModels(allModels);
+
+        return super.postProcessAllModels(objs);
+    }
+
     @Override
     public ModelsMap postProcessModels(ModelsMap objs) {
         for (ModelMap model : objs.getModels()) {
@@ -666,6 +680,66 @@ public void postProcessModelProperty(CodegenModel model, CodegenProperty propert
         }
     }
 
+    private void postProcessOneOfModels(List<ModelMap> allModels) {
+        final HashMap<String, List<String>> oneOfMapDiscriminator = new HashMap<>();
+
+        for (ModelMap mo : allModels) {
+            final CodegenModel cm = mo.getModel();
+
+            final CodegenComposedSchemas cs = cm.getComposedSchemas();
+
+            if (cs != null) {
+                final List<CodegenProperty> csOneOf = cs.getOneOf();
+
+                if (csOneOf != null) {
+                    for (CodegenProperty model : csOneOf) {
+                        // Generate a valid name for the enum variant.
+                        // Mainly needed for primitive types.
+                        String[] modelParts = model.dataType.replace("<", "Of").replace(">", "").split("::");
+                        model.datatypeWithEnum = StringUtils.camelize(modelParts[modelParts.length - 1]);
+
+                        // Primitive type is not properly set, this overrides it to guarantee adequate model generation.
+                        if (!model.getDataType().matches(String.format(Locale.ROOT, ".*::%s", model.getDatatypeWithEnum()))) {
+                            model.isPrimitiveType = true;
+                        }
+                    }
+
+                    cs.setOneOf(csOneOf);
+                    cm.setComposedSchemas(cs);
+                }
+            }
+
+            if (cm.discriminator != null) {
+                for (String model : cm.oneOf) {
+                    List<String> discriminators = oneOfMapDiscriminator.getOrDefault(model, new ArrayList<>());
+                    discriminators.add(cm.discriminator.getPropertyBaseName());
+                    oneOfMapDiscriminator.put(model, discriminators);
+                }
+            }
+        }
+
+        for (ModelMap mo : allModels) {
+            final CodegenModel cm = mo.getModel();
+
+            for (CodegenProperty var : cm.vars) {
+                var.isDiscriminator = false;
+            }
+
+            final List<String> discriminatorsForModel = oneOfMapDiscriminator.get(cm.getSchemaName());
+
+            if (discriminatorsForModel != null) {
+                for (String discriminator : discriminatorsForModel) {
+                    for (CodegenProperty var : cm.vars) {
+                        if (var.baseName.equals(discriminator)) {
+                            var.isDiscriminator = true;
+                            break;
+                        }
+                    }
+                }
+            }
+        }
+    }
+
     @Override
     public void postProcessParameter(CodegenParameter parameter) {
         super.postProcessParameter(parameter);

modules/openapi-generator/src/main/resources/rust/model.mustache

@@ -131,6 +131,9 @@ pub struct {{{classname}}} {
     {{#isByteArray}}
     {{#vendorExtensions.isMandatory}}#[serde_as(as = "serde_with::base64::Base64")]{{/vendorExtensions.isMandatory}}{{^vendorExtensions.isMandatory}}#[serde_as(as = "{{^serdeAsDoubleOption}}Option{{/serdeAsDoubleOption}}{{#serdeAsDoubleOption}}super::DoubleOption{{/serdeAsDoubleOption}}<serde_with::base64::Base64>")]{{/vendorExtensions.isMandatory}}
     {{/isByteArray}}
+    {{#isDiscriminator}}
+    #[serde(default = "{{{classname}}}::_name_for_{{#lambda.camelcase}}{{{name}}}{{/lambda.camelcase}}")]
+    {{/isDiscriminator}}
     #[serde(rename = "{{{baseName}}}"{{^required}}{{#isNullable}}, default{{^isByteArray}}, with = "::serde_with::rust::double_option"{{/isByteArray}}{{/isNullable}}{{/required}}{{^required}}, skip_serializing_if = "Option::is_none"{{/required}}{{#required}}{{#isNullable}}, deserialize_with = "Option::deserialize"{{/isNullable}}{{/required}})]
     pub {{{name}}}: {{!
     ### Option Start
@@ -172,6 +175,16 @@ impl {{{classname}}} {
         }
     }
 }
+{{#vars}}
+{{#isDiscriminator}}
+
+impl {{{classname}}} {
+    fn _name_for_{{#lambda.camelcase}}{{{name}}}{{/lambda.camelcase}}() -> String {
+        {{#defaultValue}}{{{.}}}{{/defaultValue}}{{^defaultValue}}String::from("{{classname}}"){{/defaultValue}}
+    }
+}
+{{/isDiscriminator}}
+{{/vars}}
 {{/oneOf.isEmpty}}
 {{^oneOf.isEmpty}}
 {{! TODO: add other vars that are not part of the oneOf}}

modules/openapi-generator/src/test/resources/3_0/oneOfDiscriminator.yaml

@@ -298,3 +298,29 @@ components:
         - $ref: '#/components/schemas/FruitType'
       discriminator:
         propertyName: fruitType
+    AppleReqDiscReservedKeyword:
+      type: object
+      required:
+        - seeds
+        - type
+      properties:
+        seeds:
+          type: integer
+        type:
+          type: string
+    BananaReqDiscReservedKeyword:
+      type: object
+      required:
+        - length
+        - type
+      properties:
+        length:
+          type: integer
+        type:
+          type: string
+    FruitOneOfDiscReservedKeyword:
+      oneOf:
+        - $ref: '#/components/schemas/AppleReqDiscReservedKeyword'
+        - $ref: '#/components/schemas/BananaReqDiscReservedKeyword'
+      discriminator:
+        propertyName: type

samples/client/others/rust/hyper/composed-oneof/src/models/obj_a.rs

@@ -13,6 +13,7 @@ use serde::{Deserialize, Serialize};
 
 #[derive(Clone, Default, Debug, PartialEq, Serialize, Deserialize)]
 pub struct ObjA {
+    #[serde(default = "ObjA::_name_for_realtype")]
     #[serde(rename = "realtype", skip_serializing_if = "Option::is_none")]
     pub realtype: Option<String>,
     #[serde(rename = "message", skip_serializing_if = "Option::is_none")]
@@ -28,3 +29,9 @@ impl ObjA {
     }
 }
 
+impl ObjA {
+    fn _name_for_realtype() -> String {
+        String::from("ObjA")
+    }
+}
+

samples/client/others/rust/hyper/composed-oneof/src/models/obj_b.rs

@@ -13,6 +13,7 @@ use serde::{Deserialize, Serialize};
 
 #[derive(Clone, Default, Debug, PartialEq, Serialize, Deserialize)]
 pub struct ObjB {
+    #[serde(default = "ObjB::_name_for_realtype")]
     #[serde(rename = "realtype", skip_serializing_if = "Option::is_none")]
     pub realtype: Option<String>,
     #[serde(rename = "description", skip_serializing_if = "Option::is_none")]
@@ -31,3 +32,9 @@ impl ObjB {
     }
 }
 
+impl ObjB {
+    fn _name_for_realtype() -> String {
+        String::from("ObjB")
+    }
+}
+

samples/client/others/rust/hyper/composed-oneof/src/models/obj_c.rs

@@ -13,6 +13,7 @@ use serde::{Deserialize, Serialize};
 
 #[derive(Clone, Default, Debug, PartialEq, Serialize, Deserialize)]
 pub struct ObjC {
+    #[serde(default = "ObjC::_name_for_realtype")]
     #[serde(rename = "realtype", skip_serializing_if = "Option::is_none")]
     pub realtype: Option<String>,
     #[serde(rename = "state", skip_serializing_if = "Option::is_none")]
@@ -28,3 +29,9 @@ impl ObjC {
     }
 }
 
+impl ObjC {
+    fn _name_for_realtype() -> String {
+        String::from("ObjC")
+    }
+}
+

samples/client/others/rust/hyper/composed-oneof/src/models/obj_d.rs

@@ -13,6 +13,7 @@ use serde::{Deserialize, Serialize};
 
 #[derive(Clone, Default, Debug, PartialEq, Serialize, Deserialize)]
 pub struct ObjD {
+    #[serde(default = "ObjD::_name_for_realtype")]
     #[serde(rename = "realtype", skip_serializing_if = "Option::is_none")]
     pub realtype: Option<String>,
     #[serde(rename = "color", skip_serializing_if = "Option::is_none")]
@@ -28,3 +29,9 @@ impl ObjD {
     }
 }
 
+impl ObjD {
+    fn _name_for_realtype() -> String {
+        String::from("ObjD")
+    }
+}
+

samples/client/others/rust/hyper/oneOf/src/models/foo.rs

@@ -26,6 +26,7 @@ pub struct Foo {
     #[serde(rename = "@baseType", skip_serializing_if = "Option::is_none")]
     pub at_base_type: Option<String>,
     /// When sub-classing, this defines the sub-class Extensible name
+    #[serde(default = "Foo::_name_for_atType")]
     #[serde(rename = "@type")]
     pub at_type: String,
     #[serde(rename = "fooPropA", skip_serializing_if = "Option::is_none")]
@@ -48,3 +49,9 @@ impl Foo {
     }
 }
 
+impl Foo {
+    fn _name_for_atType() -> String {
+        String::from("Foo")
+    }
+}
+

samples/client/others/rust/hyper/oneOf/src/models/foo_ref.rs

@@ -26,6 +26,7 @@ pub struct FooRef {
     #[serde(rename = "@baseType", skip_serializing_if = "Option::is_none")]
     pub at_base_type: Option<String>,
     /// When sub-classing, this defines the sub-class Extensible name
+    #[serde(default = "FooRef::_name_for_atType")]
     #[serde(rename = "@type")]
     pub at_type: String,
     /// Name of the related entity.
@@ -53,3 +54,9 @@ impl FooRef {
     }
 }
 
+impl FooRef {
+    fn _name_for_atType() -> String {
+        String::from("FooRef")
+    }
+}
+