Unknown column 'gamechess0_.playerBlack' in 'field list'

Amorgos · **Joined:** Wed Mar 15, 2006 3:20 pm **Posts:** 7

Hi,
I hope you can help, I really don't understand why I'm getting the following error

Code:

0    [main] ERROR org.hibernate.util.JDBCExceptionReporter  - Unknown column 'gamechess0_.playerBlack' in 'field list'

Hibernate version: 3.1 MySQL Version: 4.1.10a

My User object Mapping:

Code:

<class name="db.objects.User" table="user">
        <id name="username" column="username" />
        
        <property name="password" column="password" />
        <property name="firstName" column="first_name" />
        <property name="lastName" column="last_name" />
        <property name="email" column="email" />
        <property name="countryId" column="country" />
        <property name="gender" column="gender" type="boolean" />
        <property name="rating" column="rating" />
        
        <set name="roles" table="user_role">
           <key column="username" />
           <element type="string" column="role" />
        </set>
        <many-to-one name="country" foreign-key="countryId" insert="false" update="false" />
    </class>

My GameChess object Mapping:

Code:

    <class name="db.objects.GameChess" table="game_chess">
        <id name="id" column="id">
            <generator class="native"/>
        </id>
        
        <property name="title" column="title" />
        <property name="playerWhiteId" column="player_white" />
        <property name="playerBlackId" column="player_black" />
        <property name="timeLimit" column="time_limit" />
        <property name="board" column="board" />
        <property name="ratingMin" column="rating_min" />
        <property name="ratingMax" column="rating_max" />
        
        <many-to-one name="playerBlack" foreign-key="playerBlackId" insert="false" update="false" />
    </class>

The country many-to-one relationship you see above is working perfectly, The playerBlack is of type User as expected...But the many-to-one relationship in the GameChess object gives me the error.

help!

thanks a lot
Eurig

Amorgos · **Joined:** Wed Mar 15, 2006 3:20 pm **Posts:** 7

I've managed to get around this problem by replacing...

Code:

<many-to-one name="playerBlack" foreign-key="playerBlackId" insert="false" update="false" />

in the GameChess object with...

Code:

<many-to-one name="playerBlack" column="player_black" insert="false" update="false" />

The player_black is the database field which I'm after. But now I'm wondering if the first one is actualy supposed to work? Can I reference the objects foreign-key or am I using it incorrectly?

Regards,
Eurig

TheXFed · **Posted:** Wed Mar 15, 2006 5:41 pm

I see 2 things here that could be the cause:

1. You are using the foreign-key property and setting that to the property name. However, I believe this foreign-key property is only used when you are generating a schema based on hibernate mapping files. That way it knows what to name the constraint.

2. If you are creating a many-to-one relationship to a User, your mapping needs fixed:

Try this as your mapping and see how that works for you. Firstly you need to specify the class the relationship is pointing to. Next you must tell it the column of the foreign key, which looks to be player_black. Thirdly, I'd remove your mapping of the playerBlackId property. You probably won't need it if you are mapping the relationship.

Code:

<many-to-one
            name="playerBlack"
            class="<your fully-qualified User object class>"
            cascade="none"
            outer-join="auto"
            update="false"
            insert="false"
            column="player_black"/>

[/code]

Amorgos · **Joined:** Wed Mar 15, 2006 3:20 pm **Posts:** 7

Thanks for your reply Chris...

You have answered a lot! But I have one question for you...

TheXFed wrote:

Code:

<many-to-one
            name="playerBlack"
            class="<your fully-qualified User object class>"
            cascade="none"
            outer-join="auto"
            update="false"
            insert="false"
            column="player_black"/>

I've looked up the outer-join="auto" attribute above and I can't seem to find it anywhere in the 3.1 documentation. What does it do, or could you point me to some text where it tells me...

Much appreciated,
Eurig

TheXFed · **Posted:** Thu Mar 16, 2006 9:19 am

Good question. Actually I generate my mapping files using XDoclet, so it must just add that one in there by default. Looking at the DTD, valid values for that are true, false, and auto. However, I cannot find any information about it in the manual.

Amorgos · **Joined:** Wed Mar 15, 2006 3:20 pm **Posts:** 7

I still can't find any info anywhere. But I presume that it uses outer-join queries when querying as opposed to select queries. Alhough i'm not sure what the "auto" does