GORM Domain Mapping Issue - sql

Question

I've got a bit of a complicated domain model I'm trying to implement and I'm having some trouble. (On top of that, I'm quite new to all this!)
I have a User domain which has multiple roles and multiple tests. The Role domain works great. The Test domain is a bit more compilciated though because it requires two foreign keys instead of just 1 like in the Role domain. The first foreign key is the user_id and the second is a uni_id (university ID).
The User domain model contains the following
class User {
static hasMany = [roles:Role, tests:Test]
Integer userId
...
static mapping = {
table 'user_data'
id generator: 'assigned', name: 'userId', type: 'long'
userId column: 'user_id'
version false
roles joinTable:[name:'user_role', key:'user_id']
tests joinTable:[name:'user_test', key:'user_id'] // Here is where I run into trouble
}
static constraints = {
}
}
The Test domain contains
class Test {
static belongsTo = User
static hasMany = [users:User]
static hasOne = [uni:Uni]
Integer testId // primary key
String testType
static mapping = {
table 'test'
id generator: 'assigned', name: 'testId', type: 'long'
testId column: 'test_id'
users joinTable:[name:'user_test', key:'test_id']
uni joinTable:[name:'user_test', key:'test_id'] // If I leave this out, everything is groovy
version false
}
static constraints = {
}
}
and the Uni domain contains
class Uni {
static belongsTo = Test
static hasMany = [tests:Test]
Integer uniId // primary key
String shortName
String fullName
static mapping = {
table 'uni'
id generator: 'assigned', name: 'uniId', type: 'long'
uniId column: 'uni_id'
version false
tests joinTable:[name:'user_test', key:'uni_id']
}
static constraints = {
}
}
If its not clear, what I'm trying to do is pull in the University ID, Test ID, and User ID to a table user_test to find based on the User ID which tests they have taken. Is there a simple way to do this?
The kinds of errors I'm getting lead me to believe that for some reason it is trying to perform all actions on the table test instead of user_test. For example,
Unsuccessful: alter table test add uni_id int not null
I'd like to be able to access the test and university information corresonding to the specific user via user.tests.testType and user.tests.uni.fullName or something to that extent. What am I doing wrong? More importantly, is there a better way to do this?! Thanks in advance!
Edit 1: something interesting I just thought of.. a user can have multiple tests, but the inverse isn’t true. A given test will never be shared among multiple people. So I think that changes things a bit.. I'll do some reading and post if I come up with anything new.
Edit 2: Here's the Role domain
class Role {
static belongsTo = User
static hasMany = [users:User]
Integer roleId
String shortName
String roleName
Integer roleLevel
static mapping = {
table 'role'
id generator: 'assigned', name: 'roleId', type: 'long'
roleId column: 'role_id'
users joinTable:[name:'user_role', column:'user_id', key:'role_id']
version false
}
static constraints = {
}
}
Edit 3: I am now trying to store all test information in the Test domain model and simply choose the Uni name to store as a field in Test, but am getting weird errors when I try this. My new files look like this
class User {
static hasMany = [roles:Role, tests:Test]
Integer userId
static mapping = {
table 'user_data'
id generator: 'assigned', name: 'userId', type: 'long'
userId column: 'user_id'
version false
roles joinTable:[name:'user_role', key:'user_id']
}
static constraints = {
}
}
and
class Test {
static belongsTo = User
Integer testId // primary key
Integer testTypeId
String testTypeName
String testUni
Date testDate
static mapping = {
table 'test'
id generator: 'assigned', name: 'testId', type: 'long'
testId column: 'test_id'
version false
}
static constraints = {
}
}
but now I'm getting the following error when I try to run it Caused by: org.hibernate.MappingException: Missing type or column for column[tests_test] on domain[User] referencing[Test]
Any idea what that's about?

Answer 1

Ok, one issue you have is that you're trying to share the User-to-Test association join table with the Test-to-Unit association. That's not going to work.
Lets look at it in database terms. I'm not an ASCII art expert, so I hope this diagram doesn't make your eyes bleed.
user_data (userId) |---|< (user_id) user_test (test_id) >|---| (testId) test
The diagram above shows the database implementation of the many-to-many association between the User and Test domain classes. You can see that the user_data.userId links to user_test.user_id and user_test.test_id links to test.testId.
Now here's where it starts to get weird. There are two different associations between Test and Uni: a bidirectional one-to-one and a one-to-many. I just don't understand that. But I want to illustrate an important issue with your join tables, so here it is.
test (testId) |---|< (test_id) user_test (uni_id) >|---| (uniId) uni
Because you're using the same join table (user_test) for two different associations you're asking GORM to create a table like this:
USER_TEST
- USER_ID
- TEST_ID
- UNIT_ID
GORM won't do that because join tables are supposed to have only two fields. Not only that, but also you're defining a many-to-many in database terms, and yet a bidirectional one-to-one and a one-to-many in GORM terms. Ouch!
TODO
The first change I recommend is to use a different join table for the Test-Uni association.

Answer 2

Finally got everything working (after a bit of modification in terms of the domain model)
class User {
static hasMany = [roles:Role, tests:Test]
Integer userId
static mapping = {
table 'user_data'
id generator: 'assigned', name: 'userId', type: 'long'
userId column: 'user_id'
version false
roles joinTable:[name:'user_role', column:'role_id', key:'user_id']
}
static constraints = {
}
}
and
class Test {
User user
Integer testId // primary key
String testType
String testUni
Date testDate
static mapping = {
table 'test'
id generator: 'assigned', name: 'testId', type: 'long'
testId column: 'test_id'
version false
}
static constraints = {
}
}
with
class Uni {
Integer uniId // primary key
String shortName
String fullName
static mapping = {
table 'uni'
id generator: 'assigned', name: 'uniId', type: 'long'
uniId column: 'uni_id'
version false
}
static constraints = {
}
}
So now what I'm doing is selecting the university from a drop down tab in my GSP and just saving it in Test as the string testUni. Then, the big change was removing all joinTables between the three and adding User user to Test. I'm still a little fuzzy on why what I was doing before didn't work, but I won't complain about a working app!