Ormlite - Constructor call failing when BaseDaoImpl is extended

问题

I have the following tables -

@DatabaseTable(tableName="b", daoClass=B_DaoImpl.class)
public class B {

   @DatabaseField
   public String b1 ;

   public B(){
     // For Ormlite
   }
}

@DatabaseTable(tableName="a", daoClass=A_DaoImpl.class)
public class A {

   @DatabaseField
   public String a1 ;

   @DatabaseField(foreign=true)
   public B b;

   public A(){
     // For Ormlite
   }
}

For these tables, the associated Dao and DaoImpl are as follows

public interface A_Dao extends Dao<A, String>{}
public interface B_Dao extends Dao<B, String>{}


public class B_DaoImpl extends BaseDaoImpl<User, String> implements B_Dao {

   public B_DaoImpl(ConnectionSource connectionSource) throws SQLException {
      super(connectionSource, B.class);
   }
}

public class A_DaoImpl extends BaseDaoImpl<User, String> implements A_Dao {

   public A_DaoImpl(ConnectionSource connectionSource) throws SQLException {
      super(connectionSource, A.class);
   }
}

Database helper is as follows:

 public class DatabaseHelperImpl extends OrmLiteSqliteOpenHelper implements DatabaseHelper {

   private A_DaoImpl aDao = null;
   private B_DaoImpl bDao = null;

   public B_DaoImpl getBDao() throws SQLException {
       if (bDao == null) {
          bDao = getDao(B.class);
       }
       return bDao;
   }

   public A_DaoImpl getA() throws SQLException {
        if (aDao  == null ) {
          aDao = getDao(A.class);
        }
        return aDao;
   }
}

Now, when I try to call -

ADao aDao = databaseHelper.getA();

it errors out with the following error:

 Could not call the constructor in class class A_DaoImpl

Now, if I do not have the foriegn key in A - ie if A does not contain public B b, it works fine. Is there something that I am missing here?

Thank you very much in advance.

回答1:

I suspect that there is cause message you are missing at the end of your exception stack trace. For example, if I duplicate your example above I get:

java.sql.SQLException: Could not call the constructor in class class 
      com.j256.ormlite.table.CustomDaoTest$A_DaoImpl
  at com.j256.ormlite.misc.SqlExceptionUtil.create(SqlExceptionUtil.java:22)
  ...
Caused by: java.lang.reflect.InvocationTargetException
  at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
  ...
Caused by: java.lang.IllegalArgumentException: Foreign field class
>>>>      com.j256.ormlite.table.CustomDaoTest$B does not have id field  <<<<<<
  at com.j256.ormlite.field.FieldType.configDaoInformation(FieldType.java:332)
  ...

Because A has a foreign field of class B, then B needs to have an id field. Identity fields are required for foreign fields.

I'm sure A and B are simplistic versions of your classes so if you post more of the exception including all of the cause information, I'll edit my answer appropriately.

来源：https://stackoverflow.com/questions/10184169/ormlite-constructor-call-failing-when-basedaoimpl-is-extended

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java

ormlite