diff --git a/src/generate-class.ts b/src/generate-class.ts
index b66aaf9..9af64db 100644
--- a/src/generate-class.ts
+++ b/src/generate-class.ts
@@ -221,9 +221,11 @@ function generateRelationClass(
     }
   });
 
-  generateRelationImportsImport(sourceFile, [
-    ...relationImports,
-  ] as Array<string>);
+  if (relationImports.size > 0) {
+    generateRelationImportsImport(sourceFile, [
+      ...relationImports,
+    ] as Array<string>);
+  }
 
   sourceFile.addClass({
     name: `${model.name}Relations`,
@@ -264,6 +266,31 @@ function generateCombinedClass(
     namedImports: [`${model.name}Base`],
   });
 
+  // Add class validator imports for relation fields
+  const validatorImports = [
+    ...new Set(
+      relationFields
+        .map((field) => getDecoratorsImportsByType(field))
+        .flatMap((item) => item),
+    ),
+  ];
+
+  if (validatorImports.length > 0) {
+    generateClassValidatorImport(sourceFile, validatorImports as Array<string>);
+  }
+
+  // Add Swagger imports if enabled
+  if (
+    config.swagger &&
+    relationFields.length > 0 &&
+    shouldImportSwagger(relationFields as PrismaDMMF.Field[])
+  ) {
+    const swaggerImports = getSwaggerImportsByType(
+      relationFields as PrismaDMMF.Field[],
+    );
+    generateSwaggerImport(sourceFile, swaggerImports);
+  }
+
   // Import relation types for the combined class
   const relationImports = new Set();
   relationFields.forEach((field) => {
@@ -293,6 +320,7 @@ function generateCombinedClass(
               hasExclamationToken: field.isRequired,
               hasQuestionToken: !field.isRequired,
               trailingTrivia: '\r\n',
+              decorators: getDecoratorsByFieldType(field, config.swagger),
             };
           },
         ),
diff --git a/tests/swagger-generation.test.ts b/tests/swagger-generation.test.ts
index b1c9ec3..97c91d5 100644
--- a/tests/swagger-generation.test.ts
+++ b/tests/swagger-generation.test.ts
@@ -70,3 +70,124 @@ describe('Swagger Generation', () => {
     expect(userModel).toContain('@ApiProperty({');
   });
 });
+
+describe('Combined Class with separateRelationFields', () => {
+  beforeAll(async () => {
+    // Build the generator first
+    await execAsync('npm run build');
+
+    // Generate models for full-features schema (has both swagger and separateRelationFields)
+    const schemaPath = path.resolve(__dirname, 'schemas/full-features.prisma');
+    await execAsync(`npx prisma generate --schema="${schemaPath}"`);
+  }, 60000);
+
+  it('should generate combined class with class-validator and Swagger decorators for relations', () => {
+    const outputPath = path.resolve(__dirname, 'generated/full-features');
+
+    // Check User combined class
+    const userModelPath = path.join(outputPath, 'models', 'User.model.ts');
+    const userModel = readFileSync(userModelPath, 'utf-8');
+
+    // Check that it imports from UserBase
+    expect(userModel).toContain('import { UserBase } from "./UserBase.model"');
+
+    // Check for class-validator imports
+    expect(userModel).toContain('import { IsDefined } from "class-validator"');
+
+    // Check for Swagger imports
+    expect(userModel).toContain(
+      'import { ApiProperty } from "@nestjs/swagger"',
+    );
+
+    // Check for relation type imports (from index file)
+    expect(userModel).toContain('import { Post } from "./"');
+
+    // Check that class extends UserBase
+    expect(userModel).toContain('export class User extends UserBase');
+
+    // Check for relation field with decorators
+    expect(userModel).toContain('posts!: Post[]');
+    expect(userModel).toContain('@IsDefined()');
+    expect(userModel).toContain(
+      '@ApiProperty({ isArray: true, type: () => Post })',
+    );
+  });
+
+  it('should generate Post combined class with decorators for author relation', () => {
+    const outputPath = path.resolve(__dirname, 'generated/full-features');
+
+    // Check Post combined class
+    const postModelPath = path.join(outputPath, 'models', 'Post.model.ts');
+    const postModel = readFileSync(postModelPath, 'utf-8');
+
+    // Check that it imports from PostBase
+    expect(postModel).toContain('import { PostBase } from "./PostBase.model"');
+
+    // Check for class-validator imports for optional relation
+    expect(postModel).toContain('import { IsOptional } from "class-validator"');
+
+    // Check for Swagger imports
+    expect(postModel).toContain(
+      'import { ApiProperty } from "@nestjs/swagger"',
+    );
+
+    // Check for relation type imports (from index file)
+    expect(postModel).toContain('import { User } from "./"');
+
+    // Check that class extends PostBase
+    expect(postModel).toContain('export class Post extends PostBase');
+
+    // Check for optional relation field with decorators
+    expect(postModel).toContain('author?: User');
+    expect(postModel).toContain('@IsOptional()');
+    expect(postModel).toContain(
+      '@ApiProperty({ required: false, type: () => User })',
+    );
+  });
+
+  it('should generate base classes without relation fields', () => {
+    const outputPath = path.resolve(__dirname, 'generated/full-features');
+
+    // Check UserBase class
+    const userBasePath = path.join(outputPath, 'models', 'UserBase.model.ts');
+    const userBase = readFileSync(userBasePath, 'utf-8');
+
+    // Should have scalar fields with decorators
+    expect(userBase).toContain('@IsInt()');
+    expect(userBase).toContain('@IsString()');
+    expect(userBase).toContain('@ApiProperty({');
+    expect(userBase).toContain('id!: number');
+    expect(userBase).toContain('email!: string');
+    expect(userBase).toContain('name?: string');
+
+    // Should NOT have relation fields
+    expect(userBase).not.toContain('posts');
+    expect(userBase).not.toContain('Post[]');
+  });
+
+  it('should generate relation classes with only relation fields', () => {
+    const outputPath = path.resolve(__dirname, 'generated/full-features');
+
+    // Check UserRelations class
+    const userRelationsPath = path.join(
+      outputPath,
+      'models',
+      'UserRelations.model.ts',
+    );
+
+    // Check if file exists
+    expect(existsSync(userRelationsPath)).toBe(true);
+
+    const userRelations = readFileSync(userRelationsPath, 'utf-8');
+
+    // Should have relation field with decorators
+    expect(userRelations).toContain('export class UserRelations');
+    expect(userRelations).toContain('posts!: Post[]');
+    expect(userRelations).toContain('@IsDefined()');
+    expect(userRelations).toContain('@ApiProperty({');
+
+    // Should NOT have scalar fields
+    expect(userRelations).not.toContain('id!: number');
+    expect(userRelations).not.toContain('email!: string');
+  });
+});