I'm struggling to get association right on Grails. Let's say I have two domain classes:
class Engine {
String name
int numberOfCylinders = 4
static constraints = {
name(blank:false, nullable:false)
numberOfCylinders(range:4..8)
}
}
class Car {
int year
String brand
Engine engine = new Engine(name:"Default Engine")
static constraints = {
engine(nullable:false)
brand(blank:false, nullable:false)
year(nullable:false)
}
}
The idea is that users can create cars without creating an engine first, and those cars get a default engine. In the CarController I have:
def save = {
def car = new Car(params)
if(!car.hasErrors() && car.save()){
flash.message = "Car saved"
redirect(action:index)
}else{
render(view:'create', model:[car:car])
}
}
When trying to save, I get a null value exception on the Car.engine field, so obviously the default engine is not created and saved. I tried to manually create the engine:
def save = {
def car = new Car(params)
car.engine = new Engine(name: "Default Engine")
if(!car.hasErrors() && car.save()){
flash.message = "Car saved"
redirect(action:index)
}else{
render(view:'create', model:[car:car])
}
}
Didn't work either. Is Grails not able to save associated classes? How could I implement such feature?
I think you need a belongsTo in your Engine ie
static belongsTo = [car:Car]
Hope this helps.
For what is worth, I finally nailed it.
The exception I got when trying to save a car was
not-null property references a null or
transient value
It was obvious that the engine was null when trying to save, but why? Turns out you have to do:
def car = new Car(params)
car.engine = new Engine(name: "Default Engine")
car.engine.save()
Since engine doesn't belongs to a Car, you don't get cascade save/update/delete which is fine in my case. The solution is to manually save the engine and then save the car.
Related
My Integration-Test for my grails application is returning a null object when I try to get a domain object using grails dynamic get method.
This is a simplified example of my problem. Lets say I have a controller TrackerLogController that uses a service TrackerLogService to save an updated Log domain for another Tracker domain.
Domain Tracker:
class Tracker {
int id
String name
static hasMany = [logs: Log]
}
Domain Log:
class Log {
int id
String comment
static belongsTo = [tracker: Tracker]
}
Controller TrackerLogController save:
def TrackerLogService
def saveTrackerLog() {
def trackerId = params.trackerId
def trackerInstance = Tracker.get(trackerId)
Log log = TrackerLogService.saveTrackerLogs(trackerInstance, params.comment)
if( log.hasErrors() ){
//render error page
}
//render good page
}
Service TrackerLogService save:
Log saveTrackerLogs( Tracker tracker, String comment) {
Log log = new Log(tracker: tracker, comment: comment)
log.save()
return log
}
So now I want to write an Integration-Test for this service but I'm not sure if I should be writing one just for the simple logic in the controller (if error, error page else good page) I would think I would write a Unit test for that, and an Integration-Test to check the persistence in the Database.
This is what I have for my Integration-Test:
class TrackerLogServiceTests {
def trackerLogService
#Before
void setUp(){
def tracker = new Tracker(id: 123, name: "First")
tracker.save()
//Now even if I call Tracker.get(123) it will return a null value...
}
#Test
void testTrackerLogService() {
Tacker trackerInstance = Tracker.get(123) //I have tried findById as well
String commit = "This is a commit"
//call the service
Log log = trackerLogService.saveTrackerLogs(trackerInstance , commit)
//want to make sure I added the log to the tracker Instance
assertEquals log , trackerInstance.logs.findByCommit(commit)
}
}
So for this example my trackerInstance would be a null object. I know the Grails magic doesn't seem to work for Unit tests without Mocking, I thought for Intigration-Tests for persistence in the DB you would be able to use that grails magic.
You can't specify the id value unless you declare that it's "assigned". As it is now it's using an auto-increment, so your 123 value isn't used. It's actually ignored by the map constructor for security reasons, so you'd need to do this:
def tracker = new Tracker(name: "First")
tracker.id = 123
but then it would get overwritten by the auto-increment lookup. Use this approach instead:
class TrackerLogServiceTests {
def trackerLogService
private trackerId
#Before
void setUp(){
def tracker = new Tracker(name: "First")
tracker.save()
trackerId = tracker.id
}
#Test
void testTrackerLogService() {
Tacker trackerInstance = Tracker.get(trackerId)
String commit = "This is a commit"
//call the service
Log log = trackerLogService.saveTrackerLogs(trackerInstance , commit)
//want to make sure I added the log to the tracker Instance
assertEquals log , trackerInstance.logs.findByCommit(commit)
}
}
Also, unrelated - don't declare the id field unless it's a nonstandard type, e.g. a String. Grails adds that for you, along with the version field. All you need is
class Tracker {
String name
static hasMany = [logs: Log]
}
and
class Log {
String comment
static belongsTo = [tracker: Tracker]
}
I have a User class which has a List field namely pt. This field is not initialized when User register his account. But when user goes this controller action :
def updatePt() {
//performs some action
def user = User.get(springSecurityService.principal.id) //find the user
user.pt = []
//on certain conditions i put values into user.pt like this
user.pt << "E"
//at last I save it
user.save()
}
But using user/show action via scaffolding I found that pt field is not saved on users object. Where I'm making a mistake?
You have to provide a static mapping in the Users domain class so that Grails knows the field must be persisted:
class User {
static hasMany = [pt: String]
}
It's possible because of validation error. Try with
if (!user.save()) {
log.error('User not saved')
user.errors.each {
log.error('User error: $it')
}
}
PS or you can use println instead of log.error
I am developing an application which queries data from an XML file and creates multiple objects with that data.
class Search {String artist}
class Performance {static belongsTo = [events:Event, artists:Artist]}
class Location {static belongsTo = [events:Event]}
class Event {static hasMany = [performances:Performance]}
class Artist {static hasMany = [performances:Performance]}
This are the domain classes (for the sake of simplicity only relationships are shown).
Then I want to create instances of this objects when the user inserts a new artist in the SearchController. I tried to do that with the following code for the save closure in the SearchController but it seems that it's not working. The resultList is a Map with the values queried from the XML file.
def save = {
def searchInstance = new Search(params)
def resultsList = searchService.lastFmVenues(params.artist)
resultsList.each{
def performanceInstance = new Performance()
def locationInstance = new Location(venue:it.venue, street:it.street, city:it.city, postcode:it.postalcode, country:it.country, lat:it.lat, lng:it.lng)
def artistInstance = new Artist(name:params.artist).addToPerformances(performanceInstance)
def eventInstance = new Event(eventId:it.eventID, title:it.eventTitle, date:it.date, location:locationInstance)
if (searchInstance.save(flush:true) && eventInstance.save(flush: true) && artistInstance.save(flush: true) && locationInstance.save(flush: true) && performanceInstance.save(flush:true)) {
flash.message = "${message(code: 'default.created.message', args: [message(code: 'search.label', default: 'Search'), searchInstance.id])}"
}
else {
render(view: "create", model: [searchInstance: searchInstance])
}
}
redirect(action: "show", id: searchInstance.id)
}
Any ideas?
Thank you.
Try saving your objects with save(failOnError: true). This will cause grails to throw an exception if the objects don't validate. The default behavior is to simply return false from the save method.
You can make failOnError the default behavior by setting grails.gorm.failOnError=true in your Config.groovy, but I wouldn't recommend it for anything besides troubleshooting.
I have a grails application that has a service that creates reports. The report is defined as:
class Report {
Date createDate
String reportType
List contents
static constraints = {
}
}
The service generates a report and populates contents as a list that is returned by createCriteria.
My problem is that my service claims to be saving the Report, no errors turn up, logging says that its all there, but when I go to call show from the controller on that report, it says contents is null.
Another relevant bit, my Service is called by an ActiveMQ message queue. The message originating from my report controller.
Controller:
class ReportController {
def scaffold = Report
def show = {
def rep = Report.get(params.id)
log.info("Report is " + (rep? "not null" : "null")) //says report is not null
log.info("Report content is " + (rep.contents? "not null" : "null")) //always says report.contents is null.
redirect(action: rep.reportType, model: [results: rep.contents, resultsTotal: rep.contents.size()])
}
}
My service that creates the report:
class ReportService {
static transactional = false
static expose = ['jms']
static destination = "Report"
void onMessage(msg)
{
this."$msg.reportType"(msg)
}
void totalQuery(msg)
{
def results = Result.createCriteria().list {
//This returns exactly what i need.
}
Report.withTransaction() {
def rep = new Report(createDate: new Date(), reportType: "totalQuery", contents: results)
log.info("Validation results: ${rep.validate()}")
if( !rep.save(flush: true) ) {
rep.errors.each {
log.error(it)
}
}
}
}
Is there something obvious that I'm missing here? My thought is that since all my unit tests work, that the hibernate context is not being passed through the message queue. But that would generate Exceptions wouldn't it? I've been beating my head on this problem for days, so a point in the right direction would be great.
Thanks,
You can't define an arbitrary List like that, so it's getting ignored and treated as transient. You'd get the same behavior if you had a def name field, since in both cases Hibernate doesn't know the data type, so it has no idea how to map it to the database.
If you want to refer to a collection of Results, then you need a hasMany:
class Report {
Date createDate
String reportType
static hasMany = [contents: Result]
}
If you need the ordered list, then also add in a List field with the same name, and instead of creating a Set (the default), it will be a List:
class Report {
Date createDate
String reportType
List contents
static hasMany = [contents: Result]
}
Your unit tests work because you're not accessing a database or using Hibernate. I think it's best to always integration test domain classes so you at least use the in-memory database, and mock the domain classes when testing controllers, services, etc.
I'm having an issue with grails. I have a domain that looks like:
class Book {
static belongsTo = Author
String toString() { title }
Author bookAuthor
String title
String currentPage
static constraints = {
bookAuthor()
title(unique:true)
currentPage()
}
}
The main thing to note is that I have title(unique:true) to avoid from adding the same book twice. However, this is causing issues. In the controller I have created:
def populate = {
def bookInstance = new Book()
def dir = 'C:/currentBooks.txt'
def bookList
bookList = readFile(dir) //read file and push values into bookList
int numOfBooks = bookList.size()
numOfBooks.times {
bookInstance.setBookAuthor(bookList.author[it])
bookInstance.setTitle(bookList.title[it])
bookInstance.setCurrentPage(bookList.title[it])
bookInstance.save()
}
}
I call populate to read a file and populate the database with new Books. The problem is that I want to update it with new values. For instance, lets say that the book already exists in the database but I have read farther into the book and want to change the currentPage so the data is changed in the file and populate is called but doesn't update the page because the title already exists.
Can someone explain how to update the results with the new values?
First of all, you need a key for your Book domain object. You have the title marked as unique, which suggests you want to use that to uniquely identify a Book. I'd recommend against that (what happens when two books have the same title?) and use the id grails provides by default. That means you'll have to store the id in your currentBooks.txt in addition to your other fields.
Once you've got an id, you can try loading an existing record from the database. If not, create a new one. For Example:
def dir = 'C:/currentBooks.txt'
def bookList
bookList = readFile(dir) //read file and push values into bookList
int numOfBooks = bookList.size()
numOfBooks.times {
def bookInstance.get(bookList.id[it])
if (!bookInstance) {
bookInstance = new Book()
}
bookInstance.setBookAuthor(bookList.author[it])
bookInstance.setTitle(bookList.title[it])
bookInstance.setCurrentPage(bookList.title[it])
bookInstance.save()
}
Alternatively, you could use the title as the id. This is a bad idea as indicated above, but it saves having to keep track of a separate id and change the format of currentBooks.txt. With Book defined as below, you could call Book.get(bookList.title[it]):
class Book {
static belongsTo = Author
String toString() { title }
Author bookAuthor
String title
String currentPage
static constraints = {
bookAuthor()
title(unique:true)
currentPage()
}
static mapping = {
id name: 'title', generator: 'assigned'
}
}