Adding a new field to an entity

Shura Capricorn :

I have created a director class

@Entity(tableName = "director")
public class Director {

    @PrimaryKey(autoGenerate = true)
    @ColumnInfo(name = "did")
    public int id;

    @ColumnInfo(name = "full_name")
    @NonNull
    public String fullName;


    public Director(@NonNull String fullName) {
        this.fullName = fullName;
    }
}

I decided to add a new column by adding a migration method and adding a field to the class

@Entity(tableName = "director")
public class Director {

    @PrimaryKey(autoGenerate = true)
    @ColumnInfo(name = "did")
    public int id;

    @ColumnInfo(name = "full_name")
    @NonNull
    public String fullName;

    @ColumnInfo(name = "age")
    public int age;

    public Director(@NonNull String fullName) {
        this.fullName = fullName;
    }
}

the method

static final Migration MIGRATION_1_2 = new Migration(1, 2) {
    @Override
    public void migrate(SupportSQLiteDatabase database) {

        String query = "ALTER TABLE 'director' ADD COLUMN 'age' INTEGER ";

        database.execSQL(query);

    }
};

When I execute the code I get this error

Caused by: java.lang.IllegalStateException: Migration didn't properly handle

And it says it expected

age=Column{name='year', type='INTEGER', affinity='3', notNull=true, primaryKeyPosition=0, defaultValue='null'}},

And found

age=Column{name='year', type='INTEGER', affinity='3', notNull=false, primaryKeyPosition=0, defaultValue='null'},

I can see the problem is on the "notnull" part but how to fix this? I want it to be null.

Amos Korir :

Try setting the default age value to 0

 static final Migration MIGRATION_1_2 = new Migration(1, 2) {

  @Override
  public void migrate(SupportSQLiteDatabase database) {
    database.execSQL(
      "ALTER TABLE 'director' ADD COLUMN 'age' INTEGER NOT NULL DEFAULT 0"
     );
  }
};