fix: fixes union type with discriminator in go

docs/migrations/version-3-to-4.md

@@ -255,7 +255,7 @@ While the above changes work for primitives, it's problematic for objects with a
 
 ```go
 type Vehicle interface {
-  IsVehicleType() bool
+  IsVehicleType()
 }
 
 type Car struct {
@@ -264,19 +264,15 @@ type Car struct {
   AdditionalProperties map[string]interface{}
 }
 
-func (serdp Car) IsVehicleType() bool {
-  return true
-}
+func (r Car) IsVehicleType() {}
 
 type Truck struct {
   VehicleType *VehicleType
   RegistrationPlate string
   AdditionalProperties map[string]interface{}
 }
 
-func (serdp Truck) IsVehicleType() bool {
-  return true
-}
+func (r Truck) IsVehicleType() {}
 
 type VehicleType uint
 
@@ -307,7 +303,7 @@ Modelina now has support for nullable and required properties in go structs. Thi
 ```go
 type info struct {
   name string // required
-  description *string // nullable 
+  description *string // nullable
   version *float64
   isDevelopment *bool
 }

src/generators/go/renderers/StructRenderer.ts

@@ -3,7 +3,8 @@ import { StructPresetType } from '../GoPreset';
 import {
   ConstrainedObjectModel,
   ConstrainedObjectPropertyModel,
-  ConstrainedReferenceModel
+  ConstrainedReferenceModel,
+  ConstrainedUnionModel
 } from '../../../models';
 import { GoOptions } from '../GoGenerator';
 import { FormatHelpers } from '../../../helpers/FormatHelpers';
@@ -71,7 +72,13 @@ export const GO_DEFAULT_STRUCT_PRESET: StructPresetType<GoOptions> = {
   },
   field({ field }) {
     let fieldType = field.property.type;
-    if (field.property instanceof ConstrainedReferenceModel) {
+    if (
+      field.property instanceof ConstrainedReferenceModel &&
+      !(
+        field.property.ref instanceof ConstrainedUnionModel &&
+        field.property.ref.options.discriminator
+      )
+    ) {
       fieldType = `*${fieldType}`;
     }
     return `${field.propertyName} ${fieldType}`;
@@ -81,10 +88,8 @@ export const GO_DEFAULT_STRUCT_PRESET: StructPresetType<GoOptions> = {
       return '';
     }
 
-    return `func (serdp ${model.name}) Is${FormatHelpers.toPascalCase(
+    return `func (r ${model.name}) Is${FormatHelpers.toPascalCase(
       model.options.discriminator.discriminator
-    )}() bool {
-  return true
-}`;
+    )}() {}`;
   }
 };

src/generators/go/renderers/UnionRenderer.ts

@@ -9,12 +9,15 @@ import {
 import { GoOptions } from '../GoGenerator';
 import { FormatHelpers } from '../../../helpers/FormatHelpers';
 
-const unionIncludesPrimitives = (model: ConstrainedUnionModel): boolean => {
-  return !model.union.every(
-    (union) =>
-      union instanceof ConstrainedObjectModel ||
-      (union instanceof ConstrainedReferenceModel &&
-        union.ref instanceof ConstrainedObjectModel)
+const unionIncludesDiscriminator = (model: ConstrainedUnionModel): boolean => {
+  return (
+    !!model.options.discriminator &&
+    model.union.every(
+      (union) =>
+        union instanceof ConstrainedObjectModel ||
+        (union instanceof ConstrainedReferenceModel &&
+          union.ref instanceof ConstrainedObjectModel)
+    )
   );
 };
 
@@ -29,10 +32,7 @@ export class UnionRenderer extends GoRenderer<ConstrainedUnionModel> {
       `${this.model.name} represents a ${this.model.name} model.`
     );
 
-    if (
-      !unionIncludesPrimitives(this.model) &&
-      this.model.options.discriminator
-    ) {
+    if (unionIncludesDiscriminator(this.model)) {
       const content: string[] = [await this.runDiscriminatorAccessorPreset()];
 
       return `${doc}
@@ -99,6 +99,6 @@ export const GO_DEFAULT_UNION_PRESET: UnionPresetType<GoOptions> = {
 
     return `Is${FormatHelpers.toPascalCase(
       model.options.discriminator.discriminator
-    )}() bool`;
+    )}()`;
   }
 };

test/generators/go/__snapshots__/GoGenerator.spec.ts.snap

@@ -254,11 +254,11 @@ exports[`GoGenerator should render interfaces for objects with discriminator 1`]
 Array [
   "// Vehicle represents a Vehicle model.
 type Vehicle interface {
-  IsVehicleType() bool
+  IsVehicleType()
 }",
   "// Cargo represents a Cargo model.
 type Cargo struct {
-  Vehicle *Vehicle
+  Vehicle Vehicle
   AdditionalProperties map[string]interface{}
 }",
   "// Car represents a Car model.
@@ -268,9 +268,7 @@ type Car struct {
   AdditionalProperties map[string]interface{}
 }
 
-func (serdp Car) IsVehicleType() bool {
-  return true
-}
+func (r Car) IsVehicleType() {}
 ",
   "// VehicleType represents an enum of VehicleType.
 type VehicleType uint
@@ -301,9 +299,7 @@ type Truck struct {
   AdditionalProperties map[string]interface{}
 }
 
-func (serdp Truck) IsVehicleType() bool {
-  return true
-}
+func (r Truck) IsVehicleType() {}
 ",
 ]
 `;