How to set a null in the database for the integer field using hibernate?

Question

I am trying to update a field in the database to null for an integer field. I am trying to do that using hibernate. I can set object field like String and any other object to null but no integer.

<?xml version="1.0" encoding="UTF-8"?>

<class name="App_Users" table="app_users" schema="bidtool">

    <id name="userId" type="int" column="user_id">           
        <generator class="assigned"/>
    </id>  

    <property name="username" type="string">
        <column name="username" length="20" not-null="true" />
    </property>
    <property name="password" type="string">
        <column name="password" length="20" not-null="true" />
    </property>
    <property name="firstname" type="string">
        <column name="firstname" length="20" />
    </property>
    <property name="lastname" type="string">
        <column name="lastname" length="20" />
    </property>
    <property name="userType" type="int">
        <column name="user_type" />
    </property>

    <many-to-one class="MasterOrg"  fetch="select"  name="masterOrg">
        <column name="master_org_id" />
    </many-to-one>

   <many-to-one class="CarrierScac"  fetch="select" name="carrierScac">
        <column name="scac" />
    </many-to-one>


     <one-to-one class="AppUserDetails" fetch="select" name="details" constrained="true"/>

    <set name="profiles" inverse="true">
        <key>
            <column name="user_id" />
        </key>
        <one-to-many class="Profiles" />
    </set>

    <set name="boilerPlates" inverse="true">
        <key>
            <column name="user_id" />
        </key>
        <one-to-many class="BoilerPlate" />
    </set>


    <set name="rates" inverse="true" >
        <key>
            <column name="user_id" />
        </key>
        <one-to-many class="BidToolRates" />
    </set>


</class>

In the above hibernate mapping code, I want to set MasterOrg field as null.

Does your database schema allow a NULL value for the master_org_id column? Maybe it's defined to use a default value. As long as your reference App_User.masterOrg = null it should just work — Brad
– Brad, Commented Jun 25, 2012 at 15:28
@JoeriHendrickx I tried to insert the null value into the database using the hibernate. The field in the database is of type primitive int. I need to insert null in the field of type int. — Alok Das Shrestha Nepali
– Alok Das Shrestha Nepali, Commented Jun 25, 2012 at 16:36
@Brad Yes my database schema allow a null value for the master_org_id column. I think the problem is being created because master_org_id is of type primitive int. It works fine for String and other object type — Alok Das Shrestha Nepali
– Alok Das Shrestha Nepali, Commented Jun 25, 2012 at 16:37
Given your mapping, the Hibernate field is of type MasterOrg: it's a many-to-one association. Setting it to null should't cause any problem. Why don't you show the code of the entity, the code you use to set it to null, and the stack trace of the exception you get? — JB Nizet
– JB Nizet, Commented Jun 25, 2012 at 22:06
@AlokDasShresthaNepali can you post the code where you set it to null and call the save? — Joeri Hendrickx
– Joeri Hendrickx, Commented Jun 26, 2012 at 15:05

ams · Accepted Answer · 2012-06-26 09:59:08Z

6

It is best to use the object wrappers for the primitive types i.e. Integer for int, Double for double, ... etc because primitive types don't allow for the possibility of null which is always possible in a database design.

Even if a value is declared not null in the database an Object type is still useful. Consider the follow scenario as an example.

@Entity 
public class ExampleEntity {
    @Column(name="some_column") // assume this column is defined not null in the database 
    private int someProperty; 

    getttes settters other fields go here

}

Assume you write the following code

ExampleEntity t = new ExampleEntity();
entityManager.persist(t);

In this example t.someProperty has a value of 0 because that is the default value for an int therefore entityManager.persist works but maybe 0 is not a valid value for that column. If you have database constraints on that column then you get an error otherwise you have bad data in the database.

If someProperty was declared with wrapper type of Integer and the developer forgets to set the somePorpety value then you will get a not null exception.

A second reason to always use wrappers is simplicity as a developer I want consistent structure across entities because code is read more often that it is written so universally using wrapper types on entities makes things predictable for some one maintaining the code 5 years from now.

edited Jun 26, 2012 at 9:59

answered Jun 25, 2012 at 19:54

ams

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4 Comments

JB Nizet Over a year ago

It's best to use object wrappers for nullable columns, and primitive types for non-nullable columns. Why would I force all the users of my entity to deal with potentially null values if the value can never be null?

JB Nizet Over a year ago

I completely disagree. If 0 is not an acceptable default value, then use proper OO design and unit tests to make sure a value is always set, by taking this value as argument of the constructor, for example. By your reasoning, if you forget to put the not null constraint, you'll also get bad data (and bad object design). Forgetting things can happen, and it leads to bugs. Correct the bugs, but don't compromise good OO design hoping this will lead to less bugs.

JB Nizet Over a year ago

And consistency is not a good reason either. By that reasoning, you should never use int, boolean or float, because sometime you use Integer, Boolean and Float. Why limit this reasoning to entities? Use the right type: Integer for nullable ints; int for non-nullable int. Entities are POJOs.

Joeri Hendrickx Over a year ago

I don't think this is an answer to the question. In code, he's not using primitive int, he's using MasterOrg. Which is nullable.

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