Configure hibernate using JPA to store Y N for type Boolean instead of 0 1

Question

Can I setup JPA hibernate to persist Boolean types as Y N  In the database  the column is defined as varchar2 1   It currently stores them as 0 1  The database is Oracle

User · Answer

I used the concept from the answer posted by @marcg and it works great with JPA 2.1. His code wasn't quite right, so I'm posted my working implementation. This will convert Boolean entity fields to a Y/N character column in the database.

From my entity class:

@Convert(converter=BooleanToYNStringConverter.class)
@Column(name="LOADED", length=1)
private Boolean isLoadedSuccessfully;

My converter class:

/**
 * Converts a Boolean entity attribute to a single-character
 * Y/N string that will be stored in the database, and vice-versa
 * 
 * @author jtough
 */
public class BooleanToYNStringConverter 
        implements AttributeConverter<Boolean, String> {

    /**
     * This implementation will return "Y" if the parameter is Boolean.TRUE,
     * otherwise it will return "N" when the parameter is Boolean.FALSE. 
     * A null input value will yield a null return value.
     * @param b Boolean
     */
    @Override
    public String convertToDatabaseColumn(Boolean b) {
        if (b == null) {
            return null;
        }
        if (b.booleanValue()) {
            return "Y";
        }
        return "N";
    }

    /**
     * This implementation will return Boolean.TRUE if the string
     * is "Y" or "y", otherwise it will ignore the value and return
     * Boolean.FALSE (it does not actually look for "N") for any
     * other non-null string. A null input value will yield a null
     * return value.
     * @param s String
     */
    @Override
    public Boolean convertToEntityAttribute(String s) {
        if (s == null) {
            return null;
        }
        if (s.equals("Y") || s.equals("y")) {
            return Boolean.TRUE;
        }
        return Boolean.FALSE;
    }

}

This variant is also fun if you love emoticons and are just sick and tired of Y/N or T/F in your database. In this case, your database column must be two characters instead of one. Probably not a big deal.

/**
 * Converts a Boolean entity attribute to a happy face or sad face
 * that will be stored in the database, and vice-versa
 * 
 * @author jtough
 */
public class BooleanToHappySadConverter 
        implements AttributeConverter<Boolean, String> {

    public static final String HAPPY = ":)";
    public static final String SAD = ":(";

    /**
     * This implementation will return ":)" if the parameter is Boolean.TRUE,
     * otherwise it will return ":(" when the parameter is Boolean.FALSE. 
     * A null input value will yield a null return value.
     * @param b Boolean
     * @return String or null
     */
    @Override
    public String convertToDatabaseColumn(Boolean b) {
        if (b == null) {
            return null;
        }
        if (b) {
            return HAPPY;
        }
        return SAD;
    }

    /**
     * This implementation will return Boolean.TRUE if the string
     * is ":)", otherwise it will ignore the value and return
     * Boolean.FALSE (it does not actually look for ":(") for any
     * other non-null string. A null input value will yield a null
     * return value.
     * @param s String
     * @return Boolean or null
     */
    @Override
    public Boolean convertToEntityAttribute(String s) {
        if (s == null) {
            return null;
        }
        if (HAPPY.equals(s)) {
            return Boolean.TRUE;
        }
        return Boolean.FALSE;
    }

}

User · Answer

This is pure JPA without using getters setters  As of 2013 2014 it is the best answer without using any Hibernate specific annotations  but please note this solution is JPA 2 1  and was not available when the question was first asked    Entity public class Person             Convert converter BooleanToStringConverter class      private Boolean isAlive                  And then    Converter public class BooleanToStringConverter implements AttributeConverter lt Boolean  String gt          Override     public String convertToDatabaseColumn Boolean value                    return  value    null  amp  amp  value     Y     N                                   Override     public Boolean convertToEntityAttribute String value            return  Y  equals value                     Edit    The implementation above considers anything different from character  Y   including null  as false  Is that correct  Some people here consider this incorrect  and believe that null in the database should be null in Java   But if you return null in Java  it will give you a NullPointerException if your field is a primitive boolean  In other words  unless some of your fields actually use the class Boolean it s best to consider null as false  and use the above implementation  Then Hibernate will not to emit any exceptions regardless of the contents of the database   And if you do want to accept null and emit exceptions if the contents of the database are not strictly correct  then I guess you should not accept any characters apart from  Y    N  and null  Make it consistent  and don t accept any variations like  y    n    0  and  1   which will only make your life harder later  This is a more strict implementation    Override public String convertToDatabaseColumn Boolean value        if  value    null  return null      else return value    Y     N           Override public Boolean convertToEntityAttribute String value        if  value    null  return null      else if  value equals  Y    return true      else if  value equals  N    return false      else throw new IllegalStateException  Invalid boolean character      value           And yet another option  if you want to allow for null in Java but not in the database    Override public String convertToDatabaseColumn Boolean value        if  value    null  return  -       else return value    Y     N           Override public Boolean convertToEntityAttribute String value        if  value equals  -   return null      else if  value equals  Y    return true      else if  value equals  N    return false      else throw new IllegalStateException  Invalid boolean character      value

User · Answer

The only way I ve figured out how to do this is to have two properties for my class  One as the boolean for the programming API which is not included in the mapping  It s getter and setter reference a private char variable which is Y N  I then have another protected property which is included in the hibernate mapping and it s getters and setters reference the private char variable directly   EDIT  As has been pointed out there are other solutions that are directly built into Hibernate  I m leaving this answer because it can work in situations where you re working with a legacy field that doesn t play nice with the built in options  On top of that there are no serious negative consequences to this approach

User · Answer

To even do better boolean mapping to Y N  add to your hibernate configuration    lt  -- when using type  yes no  for booleans  the line below allow booleans in HQL expressions  -- gt   lt property name  hibernate query substitutions  gt true  Y   false  N  lt  property gt    Now you can use booleans in HQL  for example    FROM     SomeDomainClass class getName       somedomainclass      WHERE somedomainclass someboolean   false

User · Answer

Hibernate has a built-in  yes no  type that would do what you want  It maps to a CHAR 1  column in the database      Basic mapping   lt property name  some flag  type  yes no   gt       Annotation mapping  Hibernate extensions     Type type  yes no   public boolean getFlag

User · Answer

To do it in a generic JPA way using getter annotations  the example below works for me with Hibernate 3 5 4 and Oracle 11g  Note that the mapped getter and setter  getOpenedYnString and setOpenedYnString  are private methods  Those methods provide the mapping but all programmatic access to the class is using the getOpenedYn and setOpenedYn methods   private String openedYn    Transient public Boolean getOpenedYn       return toBoolean openedYn      public void setOpenedYn Boolean openedYn      setOpenedYnString toYesNo openedYn        Column name    OPENED YN   length   1  private String getOpenedYnString       return openedYn     private void setOpenedYnString String openedYn      this openedYn   openedYn      Here s the util class with static methods toYesNo and toBoolean   public class JpaUtil        private static final String NO    N       private static final String YES    Y        public static String toYesNo Boolean value            if  value    null              return null          else if  value              return YES          else             return NO             public static Boolean toBoolean String yesNo            if  yesNo    null              return null          else if  YES equals yesNo               return true          else if  NO equals yesNo               return false          else             throw new RuntimeException  unexpected yes no value     yesNo

[java] Configure hibernate (using JPA) to store Y/N for type Boolean instead of 0/1

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