I need to customize the column names for composite foreign keys in GORM, and I didn't find any document that shows how to do it. I know how to customize PK columns, and how to customize a single-column FK, but not multi-column FK. Is it possible at all?
Thanks.
A domain class with composite id must implement the Serializable interface.
class Person implements Serializable {
...
}
You need the "id: composite" construct in your object mapping closure.
I have to leave for work, so here it is in brief:
class Person {
String firstName
String lastName
static mapping = {
id composite:['firstName', 'lastName']
}
}
Grails: Object Relational Mapping
Related
How can I use Relate and unique using aqueduct ORM?
In my code I want that the userapp be unique?
If I try to put #Column(unique: true) I receive a error like this:
*** Relationship 'userapp' on '_Professional' cannot both have 'Column' and 'Relate' metadata. To add flags for indexing or
nullability to a relationship, see the constructor for 'Relate'.
My code below:
class Professional extends ManagedObject<_Professional> implements _Professional {}
class _Professional {
#primaryKey
int id;
#Relate(#professionals)
Userapp userapp;
#Column(defaultValue: 'true')
bool active;
ManagedSet<ProfessionalSpecialty> professionalSpecialties;
}
Whether the foreign key column underlying userapp is unique or not is determined by the inverse relationship property. In this case, the inverse is Userapp.professionals.
If Userapp.professionals is of type Professional, then a unique constraint is added to userapp; this is a 'has-one' relationship.
If Userapp.professionals is of type ManagedSet<Professional>, no unique constraint is applied; this is a 'has-many' relationship.
I'd guess that because you are using the plural form (professionals) that you are declaring a ManagedSet<Professional>. Change the declaration in the _Userapp table definition and make sure your inverse matches in _Professional:
class _Userapp {
...
Professional professional;
}
class _Professional {
...
#Relate(#professional)
Userapp userapp;
}
I am having a GORM issue.
I try to map one domain Object with another with hasMany.
class PrototypePriceModifierCode {
...
static hasMany = [activitys:Activity]
...
}
Since I don't need a back reference in Class Activity I don't have any reference to PrototypePriceModifierCode.
Having only this creates my mapping table as expected (1).
prototype_price_Modifier_code_id activity_id
In the Activity, I need a reference to a PrototypePriceModifier, which has nothing to do with the above mapping table.
The problem is that the mapping table is not generated anymore as soon as I define
class Activity{
...
PrototypePriceModifierCode prototypePriceModifierCodeAttached
How can I get the mapping table created and having a reference to PrototypePriceModifierCode in my Activity domain class?
Try like this:
class Activity {
static belongsTo = [PrototypePriceModifierCode]
}
This way, there will be a column in the activity table for PrototypePriceModifierCode instead of creating a separate table for hasMany.
When Activity does not have the prototypePriceModifierCodeAttached property, the hasMany in PrototypePriceModifierCode results in a uni-directional one-to-many association. In the database, this is implemented with a mapping table.
However, when Activity has the prototypePriceModifierCodeAttached property the association changes to a bi-directional one-to-many. In the database this means the activity table has a foreign key pointing to it's prototype_price_modifierCode, so the mapping table is not used. You can read more about these differences here.
"prototypePriceModifierCodeAttached" property
If you want a uni-directional one-to-many and the property Activity.prototypePriceModifierCodeAttached, you can create a getter method which looks up the PrototypePriceModifierCode:
class Activity {
PrototypePriceModifierCode getPrototypePriceModifierCodeAttached() {
PrototypePriceModifierCode.where {
activitys.id == this.id
}.get()
}
}
The downside here is that the property is inaccessible to GORM; can't query on it.
"price_modifier_code_id" column
On the other hand, if what you want is a price_modifier_code_id column in the activity table, you can add it as a long:
class Activity {
long prototypePriceModifierCodeAttached
static mapping = {
prototypePriceModifierCodeAttached column: 'price_modifier_code_id'
}
}
This makes it possible to use GORM queries on the property, but only on the PrototypePriceModifiedCode ID, not the domain class instance itself.
A combo
You can combine both approaches, as long as you're willing to do a bit of maintenance:
class Activity {
long priceModifierCodeId // <--- You gotta maintain this property manually.
PrototypePriceModifierCode getPrototypePriceModifierCodeAttached() {
PrototypePriceModifierCode.get(priceModifierCodeId)
}
}
Note: activitys is misspelled. It should be activities.
I ended up using String saving comma separated ids.
String activitys
this.activitys.split(',')each{
p.activitys.add(Activity.get(Long.parseLong(it)))
}
As I don't need referencial integrity here this works fine for me.
I have legacy database and some tables have composite ids
class Client {
String id
static hasMany = [
settings: Setting
]
static mapping = {
id column: 'client_id', generator: 'assigned'
}
}
class Setting {
Client client
String nodeId
String ccyPairPattern
Character qualifier
static mapping = {
id composite: ['client', 'nodeId', 'pattern', 'qualifier']
}
}
I want to delete entry from GORM association:
client.get('1').removeFromSettings(settingToRemove)
// settingToRemove.delete(flush: true)
// delete-orphans does not help
This always raises exception after flush
org.hibernate.StaleObjectStateException: Row was updated or deleted by another transaction (or unsaved-value mapping was incorrect) :
This happens because method removeFrom* sets client property to null and generates query to delete with clientId = null as client is part of composite key
What is the best solution in this case. Looks like GORM has poor support for composite keys or my mapping is incorrect.
When you use hasMany without a belongsTo on the many side, in other words a unidirectional association, you get a join table. For example...
class PurchaseOrder {
static hasMany = [items: Item]
}
class Item { }
Would yield three database tables: purchase_order, item, and purchase_order_items. The purchase_order_items table would contain two columns: purchase_order_id and item_id. You can read more about join tables here.
Since you're dealing with a legacy database, I think the best solution is not to use addTo*() and removeFrom*().
Ensure you don't have a join table. If you have a join table, remove the hasMany association.
You'll need to add/remove Setting instances manually.
Example:
def client = Client.get(1)
// Adding a setting
def setting = new Setting(client: client, nodeId: blah...)
setting.save()
// Removing a setting
/*
The prototype is used to search for a domain instance with a composite primary key.
So simply set the composite key properties accordingly.
*/
def prototype = new Setting(client: client, nodeId: blah...)
def setting = Setting.get(prototype)
setting.delete()
Lacking a hasMany association, you won't be able to access a client's settings via the client.settings property. Instead you'd have to query for them like this:
def settings = Setting.findByClient(client)
A consequence of using a legacy database is that if the database doesn't align with that GORM/Hibernate expects it will be limited in what it can do for you.
Motivation : My EF4.1 DbContext is saving Entities in the wrong order
Reason : Lack of navigation properties on my models
How I want to fix it :
I want to set up foreign key relationships in my DbContext. The catch is that my entity objects have no navigation properties (I'm using it to populate a web service and then firing DTO objects over to my application).
The classes below would be an example. In MinorClass, I want to configure my context so that it knows MajorClassID is a foreign key. The articles I've been finding on the internet on how to explicitly define Foreign Keys involve using navigational properties, which my objects dont have.
Is there a way to map this relationship?
public class MinorClass
{
public Guid ID {get;set:}
public Guid MajorClassID {get;set;} // foreign key
public string Name {get;set;}
}
public class MajorClass
{
public Guid ID {get;set;}
public string Name {get;set;}
}
Navigation property is primary construct whereas foreign key is helper (imho wrong helper). EF recognizes ordering of DB commands by relationships which are defined by navigation properties. You cannot define relation just by foreign key. You need navigation property on at least one side of the relation.
I have same type of tables
ProductCodeTable, CountrycodeTable etc
All have key, value as their fields
When I use entity frame work,
Can I have a single entity for all these tables such that I can formulate different queries to get data from different tables?
You can create a base class for all of them and create sub class for each entity
public abstract class LookUpEntity
{
[Key]
public int Key { get; set; }
[Required]
public string Value { get; set; }
}
[Table("ProductCodeTable")]
public class ProductCode : LookUpEntity
{
}
This way you can model the relationships also and later if you wanted to add specific properties to those look up entities with out affecting other entities.
You can create a view with a Union of all tables like this:
create view AllKeyTables as
SELECT 'Product' as table, Productkey as Key, nameProduct as name
FROM ProductCodeTable
UNION
SELECT 'Country' as table, CountryISO as key, CountryName as name
FROM CountrycodeTable
UNION
...
Then update EF model and check 'table' and 'key' fields as Entity Primary Key.
Next question you will do is: 'How can I make a relation between this Entity and existing Entities?' The answer is 'you can't because EF is not able to join Entities between other fields than primary key'. Then, before implement this solution, be sure that this is you are looking for.
EF supports this only if you model it as inheritance (#Eranga showed it in code-first approach). You will have single base entity and derived entity for each table so you will not avoid having different type for each table. Otherwise the answer is no.
Inheritance will put additional requirements on data in your tables. For example Ids will have to be unique among all tables. So if ProductTableCode will have record with Id 1, CountryCodeTable (and any other code table) mustn't have record with Id 1.
Also inheritance in EF can produce nasty and very poorly performing queries.