I use hasOne for one-to-one relation in Grails:
class MyParent {
static hasOne = [child: MyChild]
}
class MyChild {
static belongsTo = [parent: MyParent]
static mapping = {
table: 'MyChild'
}
}
I have table in the DB named "MyChild" and thus I get the next error:
Invalid object name 'my_child'
How can I specify relation's table name in Parent class to be "MyChild" and not "my_child"?
Try it without ':'.
static mapping = { table "mychild"}
or use name label
static mapping = { table name:"mychild" }
Hope this helps
Related
I have this class:
class Word {
String word
static hasMany = [group: WordGroup]
static belongsTo = [language: Language]
static constraints = {
word(unique: ['language'], maxSize:255)
}
}
Which is working fine, but I would need to associate the unique constraint to both language and group, so different groups can insert the same "word".
The groups are in an intermediate table (WordGroup) as this is a many to many relationship.
If I try to do
word(unique: ['language', 'group'], maxSize:255)
I get the error
Missing IN or OUT parameter in index:: 3
Is there a way to do this?
EDIT: I am adding the other classes referenced in the Word class if it helps
WordGroup
class WordGroup {
static belongsTo = [word: Word, group: Group]
static constraints = {}
}
Group
class Group {
String name
String url
static hasMany = [words: Word]
static constraints = {
name blank: false, unique: true
}
}
Language
class Language {
String name
String code
static constraints = {
name maxSize:255
code maxSize:255
}
}
Thanks.
I see there is a strategy for a one to one mapping for domain objects across different databases. But I am trying to associate two Domain objects that are in different datasources and have a one to many relationship.
class DomainA {
// default data source
}
class DomainB {
static hasmany = [domainA: DomainA]
static mapping = {
datasource 'ds2'
}
}
Any suggestions on how to make this work? Or a workaround?
Found a solution to this and it works pretty well. Solution is to create a join table in the schema you own.
E.g.
class DomainA {
// default data source
}
class DomainB {
List<DomainA> domainAList
static transients = ['domainAList']
static hasmany = [domainAIds: Integer]
static mapping = {
datasource 'ds2'
domainAIds joinTable: [name: 'DOMAINB_DOMAINA', key: 'DOMAINB_ID', column: 'DOMAINA_ID']
}
List<DomainA> getDomainAList(){
domainAList = domainAIds.collect { DomainA.get(it) }
domainAList
}
}
I am new to grails. I have the following requirement, how to achieve it ?
class File {
list<Employee> listOfCaseWorkersWhoHaveWorkedOnThisFile; <<<---- how to achieve this ?
static constraints = {
}
}
class Employee {
list<File> filesOwnedByHim <<<<<-------- also this ?
static constraints = {
}
}
My requirement is that a File will have a list of Employees with zero or more elements and same for Employee.
Do I have to implement one of the GORM (one-to-one, one-to-many etc) here ? If yes how ?
You can use hasMany which is one-to-many association between your classes.
class File {
static hasMany = [employees: Employee]
static constraints = {
}
}
class Employee {
static hasMany = [files: File]
static constraints = {
}
}
Then you can easily use GORM operations on it (addTo,findBy,etc).
Ref: http://grails.org/doc/latest/ref/Domain%20Classes/hasMany.html
I'm creating a (theoretically) simple hasMany relationship within a domain class. I have two tables with a foreign key relationship between the two. Table 1's domain object is as follows:
Functionality{
String id
static hasMany = [functionalityControllers:FunctionalityController]
static mapping =
{
table 'schema.functionality'
id column:'FUNCTIONALITY_NAME', type:'string', generator:'assigned'
version false
}
}
and domain object 2
FunctionalityController
{
String id
String functionalityName
String controllerName
static mapping =
{
table 'schema.functionality_controller'
id column:'id', type:'string', generator:'assigned'
version:false
}
}
The issue I am having is that when I have the hasMany line inside of the Functionality domain object, the app won't start (both the app and the integration tests). The error is org.springframework.beans.factory.BeanCreationException leading to Invocation of init method failed; nested exception is java.lang.NullPointerException.
Any help would be appreciated.
UPDATE:
*Working Domains*:
class Functionality {
String id
static hasMany = [functionalityConts:FunctionalityCont]
static mapping =
{
table 'schema.functionality'
id column:'FUNCTIONALITY_NAME', type: 'string', generator: 'assigned'
functionalityConts( column:'functionality_name')
version false;
}
}
and
class FunctionalityCont {
String id
String functionalityName
String controllerName
static belongsTo = [functionality: Functionality]
static contraints = {
}
static mapping =
{
table 'schema.functionality_controller'
id column:'id', type: 'string', generator: 'assigned'
functionality(column:'FUNCTIONALITY_NAME')
version false;
}
}
Well 2 things...
1.I'm not sure but I guess that your domain class with the prefix 'Controller' maybe is the responsible, this is because grails is convention over configuration and by convention the controller class ends with Controller prefix and are in the controller folder, in this case is a lil' confusing
2.In GORM and in this case the relationship between objects can be unidirectional or bidirectional, is your decision to choose one, but in both cases there are different implementations, the class Functionality(btw is missing the 'class' word) has the right relationship to FunctionalityController through hasMany, but FunctionalityController doesn't knows about the relationship, so you can implement:
// For unidirectional
static belongsTo = Functionality
// For bidirectional
static belongsTo = [functionality:Functionality]
// Or put an instance of Functionality in your domain class,
// not common, and you manage the relationship
Functionality functionality
So check it out and tell us pls...
Regards
Try adding
static belongsTo = [functionality: Functionality]
to your FunctionalityController class. I suspect there is more to your error than what you've shown, but generally a hasMany needs an owning side to it. Since that is where the foreign key actually lives.
I have a Grails domain class that is a hierarchy of categories. Each Category has a parent category (except for the root category which is null).
class Category {
String name
static mapping = {
cache true
name index:'category_name_idx'
}
static belongsTo = [parent:Category]
static constraints = {
parent(nullable:true)
}
}
My problem: deletes cascade exactly opposite of what I'd expect:
someSubCategory.delete() deletes the category then tries to delete the parent category (which fails with an integrity violation if the parent has other children).
parentCategory.delete() does NOT cascade delete its children, but instead just fails with an integrity violation.
What am I doing wrong? My understanding is that the 'belongsTo' above should tell the GORM to cascade deletes from the parent to all children, but not from a child to its parent.
If I am understanding correctly a Category belongs to a parent and a parent can have multiple children, so I think you need a hasMany relationship, something like this:
class Category {
String name
static mapping = {
cache true
name index:'category_name_idx'
}
static belongsTo = [parent:Category]
static hasMany = [children: Category]
static constraints = {
parent(nullable:true)
}
}
I had had similar structures and never have issues with the delete doing it this way.
Hope this helps!
It's not an answer, but I found a workaround to my own question. You can remove the belongsTo = [parent:Category], replacing it with a simple instance variable. This stops subCategory.delete() from cascading to the parent.
class Category {
String name
Category parent
static mapping = {
cache true
name index:'category_name_idx'
}
static constraints = {
parent(nullable:true)
}
}