docs/geode-native-docs-cpp/serialization/cpp-serialization/using-enum-type-with-pdx.html.md.erb

---
title:  Using C++ Enum Type with PDX Serialization
---

<!--
Licensed to the Apache Software Foundation (ASF) under one or more
contributor license agreements.  See the NOTICE file distributed with
this work for additional information regarding copyright ownership.
The ASF licenses this file to You under the Apache License, Version 2.0
(the "License"); you may not use this file except in compliance with
the License.  You may obtain a copy of the License at

     http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
-->

Because there is no "object" base type in C++, enums cannot be directly passed as parameters to the `writeObject` and `readObject` API.

To use the C++ enum type with PDX serialization, you have to wrap the `enum` in the `CacheableEnum` class type by specifying classname, enumname and ordinal.

``` pre
enum enumQuerytest { id1, id2, id3 };
 class TESTOBJECT_EXPORT PdxEnumTestClass :public PdxSerializable
  {
  private:
    int m_id;
    CacheableEnumPtr m_enumid;

  public:
    int getID(){
      return m_id;
    }

    CacheableEnumPtr getEnumID() {
      return m_enumid;
    }

    PdxEnumTestClass(int id)
    {
      m_id = id;
      switch (m_id) {
        case 0:
          m_enumid = CacheableEnum::create("enumQuerytest", "id1", id1);
          break;
        case 1:
          m_enumid = CacheableEnum::create("enumQuerytest", "id2", id2);
          break;
        case 2:
          m_enumid = CacheableEnum::create("enumQuerytest", "id3", id3);
          break;
        default:
          m_enumid = CacheableEnum::create("enumQuerytest", "id1", id1);
          break;
      }
    }

    PdxEnumTestClass() { }

    void toData(PdxWriterPtr pw) {
      pw->writeInt("m_id", m_id);
      pw->writeObject("m_enumid", m_enumid);
    }

    void fromData(PdxReaderPtr pr) {
      m_id = pr->readInt("m_id");
      m_enumid = pr->readObject("m_enumid");
    }

    CacheableStringPtr toString() const {
      return CacheableString::create("PdxEnumTestClass");
    }

    char* GetClassName() const {
      return "com.example.PdxEnumTestClass";
    }

    static PdxSerializable* createDeserializable() {
      return new PdxEnumTestClass();
    }
  };
```

## <a id="concept_F38FDBC327204B4EB1E0BC74B4C95409__section_3491F76DB8C0464D89418B89372BBAEA" class="no-quick-link"></a>How Puts and Queries Work on Enums

The following code sample demonstrates how put and query operations work when using the C++ enum Type with PDX serialization:

``` pre
//Creating objects of type PdxEnumTestClass
PdxEnumTestClassPtr pdxobj1(new PdxEnumTestClass(0));
PdxEnumTestClassPtr pdxobj2(new PdxEnumTestClass(1));
PdxEnumTestClassPtr pdxobj3(new PdxEnumTestClass(2));

RegionPtr rptr = getHelper()->getRegion( "DistRegionAck" );

//PUT Operations
rptr->put( CacheableInt32::create(0), pdxobj1 );
LOG( "pdxPut 1 completed " );

rptr->put( CacheableInt32::create(1), pdxobj2 );
LOG( "pdxPut 2 completed " );

rptr->put( CacheableInt32::create(2), pdxobj3 );
LOG( "pdxPut 3 completed " );


//Query
try {
    Serializable::registerPdxType(PdxEnumTestClass::createDeserializable);
    LOG("PdxEnumTestClass Registered Successfully....");
} catch (geode::IllegalStateException&/* ex*/) {
    LOG("PdxEnumTestClass IllegalStateException");
}

RegionPtr rptr = getHelper()->getRegion( "DistRegionAck" );
SelectResultsPtr results = rptr->query("m_enumid.name = 'id2'");  
ASSERT(results->size()== 1 , "query result should have one item");
ResultSetPtr rsptr = dynCast<ResultSetPtr>(results);
SelectResultsIterator iter = rsptr->getIterator();  
while (iter.moveNext()) {
    PdxEnumTestClassPtr re = dynCast<PdxEnumTestClassPtr>(iter.current());
    ASSERT(re->getID()== 1 , "query should have returned id 1");
}    
```