I need to map Domain classes and subclasses of a legacy database.
The model thath I need to recreate with Grails is to this tables:
Tables structure
CARD_PAYMET and CHEQUE_PAYMENT is subclasses of PAYMENT and share a composite key of two field: OrderId and PaymentId.
I try some ex scenarios, but I can´t arrive to solution. None of then recreate the same model data, and I can´t change this model.
Can any one help me?
Thanks.
Your database looks like a good fit for table-per-subclass inheritance. First, since you're using a composite primary key, your domain classes need to implement the Serializable interface. Then it's a matter of mapping each table column to a property.
import groovy.transform.EqualsAndHashCode
#EqualsAndHashCode(includes=['orderId', 'paymentId'])
class Payment implements Serializable {
int orderId
int paymentId
float amount
static mapping = {
version false
tablePerHierarchy false
id composite: ['orderId', 'paymentId']
orderId column: 'OrderId'
paymentId column: 'PaymentId'
/* Assuming case-insensitive db, so I left out 'Amount'. */
}
}
class CardPayment extends Payment {
String cardType
static mapping = {
version false
cardType column: 'CardType'
}
}
class ChequePayment extends Payment {
int checkNumber
static mapping = {
version false
checkNumber column: 'CheckNumber'
}
}
Note: In this example I used Groovy's EqualsAndHashCode AST transformation to implement Serializable.
With the domain classes in place you'll be able to do GORM polymorphic queries:
def payments = Payment.list() // All Payments (Payment, CardPayment, and ChequePayment).
def cardPayments = CardPayment.list() // Only CardPayments.
...
def nicePayments = Payment.where { amount > 1000 }.list()
Related
With Grails 3.2.5, hibernate 5.1.2 core.
I have a legacy database that has several clobs in a table. In order to avoid eager fetching, in earlier versions of Grails I defined a domain class that contained only those clobs in order to make them accessed via an (apparent) association which could then be lazily fetched. A sketch of the setup:
class Comment {
String someField // eager
CommentText cmntText // lazy
static mapping = {
id column: 'COMMENT_ID', generator:'sequence', params:[sequence:'cmnt_seq']
}
In a separate domain class file:
class CommentText {
String userComment
static mapping = {
table 'COMMENT'
id generator:'assigned'
userComment sqlType:'clob'
}
As noted, clob column 'user_comment' exists in the single table 'COMMENT'.
In 3.2.5, when doing this I get an error that column 'comment_text_id' is not defined in table 'comment'. This didn't use to be the case, nor should the field have to exist.
On a similar note, in another case I define a composite domain class (a class defined in the same file as the actual domain class). In this case too I get an error about a missing id:
class A {
B b
}
class B {
String someField
}
In this case I get an error saying that field b_id is not in table 'A'. But - it's supposed to be embedded composition, it should not be there.
I'm building within Intellij if that is relevant.
With GORM 6.1 this is now possible with a single domain class
import grails.gorm.hibernate.annotation.ManagedEntity
import static grails.gorm.hibernate.mapping.MappingBuilder.*
#ManagedEntity
class Comment {
String someField
String userComment
static constraints = {
}
static final mapping = orm {
id {
generator("sequence")
params(sequence:'cmnt_seq')
}
userComment = property {
lazy(true)
column {
sqlType 'clob'
}
}
}
}
I needed to create a custom join table to re-model a many-to-many mapping and following some great posts on here came up with the model below.
Now my question is, if I have either a Course or Journey object in a GSP, how do I access the extra column data belonging to the join table.
In this example, I want to access the field named extraColumn1 in the CourseJourneyDetail within my GSP if I have either a journey or course instance
I've tried the following :
${course.courseJourneyDetail.extraColumn1}
but it didn't work.
Here are (relevant parts of) my domain classes :
class Course {
static hasMany = [journies: CourseJourneyDetail]
String courseName
String organisersDescription
Set<Journey> getJournies() {
return CourseJourneyDetail.findAllByCourse(this)*.journey
}
}
class Journey {
static hasMany = [courses: CourseJourneyDetail]
java.util.Date dateCreated
java.util.Date lastUpdated
boolean enabled = true
User user
Set<Course> getCourses() {
return CourseJourneyDetail.findAllByJourney(this)*.course
}
}
class CourseJourneyDetail implements Serializable {
String extraColumn1
static belongsTo = [course: Course, journey: Journey]
boolean equals(other) {
if (!(other instanceof CourseJourneyDetail)) {
return false
}
other.journey?.id == journey?.id &&
other.course?.id == course?.id
}
int hashCode() {
def builder = new HashCodeBuilder()
if (course) builder.append(course.id)
if (journey) builder.append(journey.id)
builder.toHashCode()
}
static constraints = {
}
static mapping = {
version false
id composite: ['course', 'journey']
}
}
Since you've established that each Course/Journey has a collection of CourseJourneyDetail's rather than a single instance, ${course.courseJourneyDetail.extraColumn1} won't work (as you've discovered).
If you break down your groovy expression into this: course.courseJourneyDetail, it doesn't really make sense based on the relationships you have created. The reason being, Course doesn't have a single CourseJourneyDetail but rather a collection.
If your desire is to have Course and Journey in a one-to-one relationship, but with a join table with additional columns, then your domain structure needs to change to reflect this: rather than using static hasHany in each class, you would switch to a single instance.
If your desire is to keep the many-to-many relationship, then you need to think about how to fetch the appropriate join object that represents the association. One example:
CourseJourneyDetail.findAllByCourseAndJourney(<courseInstance>, <journeyInstance>)
If you want the additional columns collected for all of the many-to-many associations, you can use a syntax that you are already using in your convience methods (getJournies and getCourses):
course.journies*.extraColumn1
This would output an array of Strings, so its usage makes less sense within a ${} expression; and more sense within a g:each. It entirely depends on how you plan on using this data.
I have an abstract Event class which holds properties shared by all Event types and beneath it I have two subclasses with one table per class (MasterEvent and ParentEvent).
The problem is that in MasterEvent the id column is of type "number" and in the ParentEvent it is of type "varchar2".
This means that when I try to run the app I get :
Caused by HibernateException: Wrong column type in * for column event_id. Found: number, expected: varchar2(255 char).
Note that this is a legacy database, so there's no chance in changing the column types on the database level.
The sample code below should help in understanding better:
Event.groovy
package a
abstract class Event {
String id
static mapping = {
tablePerHierarchy "false"
id column: "id"
}
}
ParentEvent.groovy
package a
class ParentEvent extends Event {
static mapping = {
id column: "id"
}
}
MasterEvent.groovy
package a
class MasterEvent extends Event {
static mapping = {
id column: "id", type: "number"
}
}
I have tried putting type: number all sorts of combinations, but it's always giving me the same error.
Is there anyway to either cast the sqlType directly to String or have grails ignore this validation?
type: 'number' does not work because it is not a hibernate basic type
Try changing it to type: 'long' (or whatever fits your legacy DB)
Also see the docs: Link
Edit after your comment
I don't know what you are doing in your abstract class, but perhaps you can do something like that and use the getter in your abstract class (not tested!):
class MasterEvent extends Event {
Long longId
static mapping = {
longId column: "id"
}
#Override
String getId() {
longId?.toString()
}
}
Did you try to define id field in subclasses? "String id" in Parent event and "long id" in Master event?
You could try a custom Hibernate UserType which takes the number id column and converts it to a String. This would then go in the MasterEvent class:
static mapping = {
id column: "id", type: NumberToStringType
}
I'm a newbie in grails. i'm having a problem right now in my domain classes. I have 3 domain classes, class Patient,class Nurse and class NursePatient, the class NursePatient is a composite key where you can see who is the attending Nurse in a Patient, so if you view its table you can only see the id's of nurses and patients. This is my code for Nurse class:
class Nurse {
String name
Nurse partner
boolean idle = true
static belongsTo = [hospital: Hospital]
static constraints = {
name(blank:false)
partner(nullable:true)
hospital(nullable:false)
}
String toString(){
"Nurse ${name}"
}
}
--> and this is my domain class for NursePatient:
class NursePatient implements Serializable{
Nurse nurse
Patient patient
static mapping = {
version false
id composite:['nurse', 'patient']
}
static constraints = {
patient(nullable:false, validator:{val, obj -> val.hospital == obj.nurse.hospital})
nurse(nullable:false)
}
String toString(){
"Nurse ${nurse.name} - ${patient.name}"
}
void saveIt(Nurse x, Patient y){
def np = new NursePatient(nurse: x, patient: y)
if(np.save()){
def n = nurse.get(nurse.id)
n.idle = false
}
}
}
--> I was asked to print a list of nurses who doesn't have a patient. I was thinking that the moment I save in table using the saveIt() method from class NursePatient, once the save() is successful it changes the value of the property idle of class Nurse from true to false so that querying is much more easier. My problem is I don't if my code in class NursePatient is correct or is it possible to change the value of a property from another class. Please Help me.. thank You!!
Changing properties of domain classes inside different classes is fine.
However, you don't really need a NursePatient class. If you declare the relationship between Nurses and Patients as many-to-many, like this:
class Nurse {
static hasMany = [patients: Patient]
...
}
class Patient {
static hasMany = [nurses: Nurse]
...
}
then Grails will create and update the needed join table automatically. You can then query for all the nurses without patients using Criteria API:
def nursesWithoutPatients = Nurse.withCriteria { isEmpty("patients") }
I have to implement map values in my Grails app.
I have a class that can contain 0..N OsmTags, and the key is unique.
In Java I would model this with a Map in each object, but I don't know how to map classes in Grails.
So I defined this class:
class OsmTag {
/** OSM tag name, e.g. natural */
String key
/** OSM tag value, e.g. park */
String value
static constraints = {
key blank:false, size:2..80,matches:/[\S]+/, unique:false
value blank:false, size:1..250,matches:/[\S]+/, unique:false
}
}
That works ok, but it's actually quite ugly because the tag key is not unique.
Is there a better way to model this issue?
Cheers
If your tags are simple strings, then you can use a map directly.
class Taggable {
Map tags // key : String, value : String
}
If I understand your question correctly, then you want to ensure that each tag is unique within a particular instance of the tagged entity?
Assume that the entity to which the tags are attached is named Taggable, then
you can enforce this requirement using a custom constraint:
class Taggable {
static hasMany = [ tags: OsmTag ]
}
class OsmTag {
static belongsTo = [ taggable: Taggable ]
/** OSM tag name, e.g. natural */
String key
/** OSM tag value, e.g. park */
String value
static constraints = {
key(blank:false, size:2..80,matches:/[\S]+/, unique:false,
validator: { val, obj ->
if (obj.taggable.tags.key.count(val > 1)) {
return false
}
}
)
value(blank:false, size:1..250,matches:/[\S]+/, unique:false)
}
}
If you're looking for a NoSQL solution, you could try using MongoDB with Grails. The most recent version (1.4) supports Geospatial indexing and querying.