I want to exclude domain field from data binding
Is it possible to mark class field by an annotation?
For example domain:
class Article {
String text
.....
Author author
}
in code I have to write bindData(article, params, [exclude: ['author']]) for cheating prevention
But much easier simple to annotate Author author. But I didn't find how.
Since Grails 2.1.0 you can use the bindable constraint to indicate that a property should not be automatically assigned during data binding.
class Article {
String text
...
Author author
static constraints = {
author bindable: false
}
}
Now calling bindData(article, params) will automatically exclude the article's author property.
Related
Is there a way to create an association to an arbitrary domain object in grails?
Something like
class ThingHolder {
DomainObject thing;
}
and then
Book b=new Book(title: "Grails 101").save()
Author a=new Author(name: "Abe").save()
ThingHolder t1=new ThingHolder(thing:b).save()
ThingHolder t2=new ThingHolder(thing: a).save()
So that
ThingHolder.get(t1.id).thing // will be a Book
and
ThingHolder.get(t2.id).thing // will be an Author.
I'm still looking for a grailsier way to do this, but this seems to get the job done.
class ThingHolder {
static constraints = {
thing bindable:true // required so 'thing' is bindable in default map constructor.
}
def grailsApplication;
Object thing;
String thingType;
String thingId;
void setThing(Object thing) { //TODO: change Object to an interface
this.thing=thing;
this.thingType=thing.getClass().name
this.thingId=thing.id; //TODO: Grailsy way to get the id
}
def afterLoad() {
def clazz=grailsApplication.getDomainClass(thingType).clazz
thing=clazz.get(thingId);
}
}
Assuming you have a Book and Author (that do not override the ID attribute for the domain object).
def thing1=new Author(name : "author").save(failOnError:true);
def thing2=new Book(title: "Some book").save(failOnError:true);
new ThingHolder(thing:thing1).save(failOnError:true)
new ThingHolder(thing:thing2).save(failOnError:true)
ThingHolder.list()*.thing.each { println it.thing }
I found some extremely useful tips in these two answers.
How to make binding work in default constructor with transient values.
How to generate a domain object by string representation of class name
UPDATE (based on comment)
Since you don't want to (or can't) extend another class in your domain model, this won't be possible using GORM.
ORIGINAL Answer
Yes, you can do this. It's called inheritance. In your case you would have a Thing which is the super class of both Author and Book.
Your domain model might look like this:
class Thing {
// anything that is common among things should be here
}
class Author extends Thing {
// anything that is specific about an author should be here
}
class Book extends Thing {
// anything that is specific about a book should be here
}
class ThingHolder {
Thing thing
}
Since both Author and Book extend Thing they are considered to be a Thing as well.
However, doing this without understanding inheritance and how Grails/GORM models the data in your database is short sighted. You should research those topics fully to make sure this is really what you want.
I am recently working on grails and would like to know how to do more complex scaffolding
For example, if I want to Scaffold a class
class Book{
Author a
Publisher p
// ....
}
Author class
class Author{
String firstName
String lastName
// ...
}
Publisher class
class Publisher{
String name
String address
// ....
}
Now if I have a BookController
class BookController{
static scaffold = true;
}
I have a layout of
Author Publisher
However if I want a layout with
AuthorID AuthorFirstName AuthorLastName PublisherName PublisherAddress
I have looked through the http://grails.org/doc/latest/guide/scaffolding.html, however, I am unable to set it to the given property. I would like to know I am able to accomplish it? A tutorial would be helpful.
The scaffolding plugin within Grails is not designed to handle these types of complex views out of the box. You have a few options:
Use the install-templates command and modify the scaffolding templates to handle your needs.
Re-design your domain class to use embedded Author and Publisher. This will change the scaffolding output, but it also will change a lot more too. I wouldn't use this option unless you understand all the changes this will make to your domain model.
Generate the code using scaffolding then customize the output to suit your needs.
Of the three options presented here I would recommend the third as it makes the most sense to address the narrow scope of your issue.
You could also use transients. But transients aren't displayed by default.
You need to modify the templates and explicitly hide otherwise hidden fields using constraints i.e. id
NOTE: code below untested, for illustration purposes only.
//optional, but allows code completion in IDE ;-P
String authorName
String getAuthorName(){
return a.firstName + ' ' + a.lastName
}
static transients = [authorName:String]
static constraints = {
id(display:false)
}
I'm beginner in Grails and I have a problem when I try to save a POGO
I have created 1 domain class
class Book {
String title
}
Then, I have generated the controller and view automatically.
Now, I want to be able to create a book with the code by clicking "create" (I know it is possible directly with the code generated but for my example I want to do it by the code). To do this, I have modified the method 'save(Book bookInstance)' in the controller like this
#Transactional
def save(Book bookInstance) {
def book = new Book(title:"New Grails Book").save()
But, when I go to the URL localhost:8080/myApp/book/create and then I click "Create", I have the error
message -> /myApp/WEB-INF/grails-app/views/book/save.jsp
description -> The requested resource is not available.
When I put this code in bootStrap, it is OK, so I don't understand why it is not in the controller
When you have a hasMany property in a domain class, Grails adds a Set property to the domain class with an AST transformation (so it's actually there in the bytecode, and it's visiable to Java) to represent the collection, and when you add a belongsTo a field of that type is added. So it's as if you had this code:
class Author {
Set<Book> books
static hasMany = [books: Book]
String name
}
and
class Book {
Author author
static belongsTo = [author: Author]
String title
}
The AST xform uses the map key as the field name, so you can use any valid field name, but the convention is to do what you did.
Properties are nullable:false by default, so your code doesn't save the Book instance because you didn't set the author property. When doing this explicitly you typically don't create the Book directly, but instead add it to the Author's collection using the dynamic addToBooks method. This sets the author field back-reference and when you save the author, the book is transitively validated and saved. This is all handled for you when you have code like new Book(params).save(), and you can do it directly, e.g.
Author author = ...
def book = new Book(title:"New Grails Book", author: author).save()
If you're using a generated controller and GSPs, there should be an author id in the params map, it'll likely be author.id, so that first line would be
Author author = Author.get(params['author.id'])
but you can add
println params
at the top of the action method to see all of the submitted params.
In general you don't want to look at the return value of the save call, since it will be null if there's a validation error and there's no way to retrieve the errors. So change
def book = new Book(...).save()
to
def book = new Book(...)
book.save()
and now you can call book.hasErrors(), book.getErrors(), book.errors, etc. to see if it was successful and if not, what went wrong.
But that's not the exact problem you're seeing, just one you will when you fix your problem. There's no save.gsp, and Grails also looks for save.jsp and confusingly includes that name in the not-found message. The save method is accessed via a POST request, typically from the form generated by the create action, and it either re-displays create.gsp with the submitted data and error messages when validation fails, or redirects to the view action when the save succeeds. There's no need for a save.gsp when using the generated code.
when i design database.I use embedded to embed common fields.but it's can't init dateCreated and createdBy,what'd i do?extends domain or embedded is right way to handle common fields?
code to say?
class Created {
Date dateCreated
Long createdBy
def beforeInsert()
{
dateCreated= new Date()
createdBy=0
}
}
class Updated {
Date lastUpdated
Long updatedBy
//it works?
def beforeUpdate(){
lastUpdated=new Date()
updatedBy=0
}
//it works?
def beforeInsert(){
lastUpdated=new Date()
updatedBy=0
}
}
class CreatedUpdated {
Created created
Updated updated
//Must use the embedded option, or the type of exception, can not find CreatedUpdated
static embedded = ['created','updated']
}
class Term {
String name
CreatedUpdated createdUpdated
static embedded = ['createdUpdated']
Term parent
static hasMany =[terms:Term]
static mapping = {
version false
}
String toString()
{
name
}
static constraints = {
name unique:true,size: 1..20
parent nullable: true
createdUpdated display:false,nullable:true
terms display:false
url url: true
}
}
or use extends?
class Term extends CreatedUpdated{
String name
Term parent
static hasMany =[terms:Term]
static mapping = {
version false
}
String toString()
{
name
}
static constraints = {
name unique:true,size: 1..20
parent nullable: true
terms display:false
url url: true
}
}
`
what is right to me?
I'd definitely make this example embedded rather than inherited. I don't think you should make this call based solely on the fact that objects contain common fields. Instead, you should use inheritance if it makes sense for your model using standard OO design techniques. For example, if "myClass is a myBaseClass" doesn't hold true, inheritance is probably the wrong solution.
In general, I'd stay away from classes like CreatedUpdated that are just a collection of properties and not an actual object from your domain. Java/Groovy has only single inheritance, so this only works if you have one base class like this.
Also, for that particular case, created and updated timestamps can automatically be applied by GORM. If you're using spring security, check out the audit-trail plugin for automatically creating createdBy and updatedBy columns.
In this particular case audit-trail plugin should suffice the requirements. However if you have such requirement for other fields wherein no plugin is available, then one of the possible solution could be to inject such common fields at compile time via AST Transformation. Internally audit-trail plugin uses this concept to inject those fields. Depending upon your requirement you can either use Global AST Transformations or Local AST Transformations.
I've been struggling to produce the right configurations to produce cascade-delete behaviour in a relatively simple Grails project.
Say I have the following simple domain classes:
class Author {
String name
static constraints = {
}
}
and
class Book {
String title
Author author
static constraints = {
}
}
If I create an author, and then create a book written by that author, I am not able to delete the Author without first manually deleting the book. I get an "Integrity constraint violation". This isn't suprising as MySQL (my underlying database) is created by Grails with a "foreign key constraint" on the "author" column of the "book" table as "Restrict" (and this behaviour is consistent with expectations from the Grails documentation as I understand it).
Now, if I were to manually change the underlying database constraint on the "author" column of the book table from "Restrict" to "Cascade", I get the behaviour I want. Namely, that if you delete the Author, all their books are also deleted.
So, what I'd like to do is change my Grails "Book" class in a way that creates the "book" table with "on delete cascade" on the author column. I've been reading plenty of information about doing this sort of thing and GORM defaults using "belongsTo" and explicit "mappings".
One way to do this, based on the documentation for "belongsTo", seemed to be to change the line in the Book class from:
Author author
to
static belongsTo = [author: Author]
Thereby making it explicit that the Author is the "owning side" of the relationship. The documentation seems to suggest that this should generate the cascade-delete behaviour I'm after. However, it doesn't work unless I add an explicit "hasMany = [books:Book]" into the Author class. I don't wish to do this. (This wish makes more sense in my actual business domain, but even just as an exercise in understanding, I don't yet get why I have to have the Author domain class know about books explicitly).
I'd just like a grails setting to change the Book class to produce the "cascade delete" setting in the database, without having to change the Author class. I tried using an explicit mapping like:
static mapping = {
author cascade: 'all'
}
and combinations of this with other explicit mapping or "belongsTo" options. This didn't work.
Noting that a simple change to the "constraints" in the underlying SQL database provides the behaviour I want, is there a way to get this through Grails? If not, have I misunderstood something fundamental here or am I trying to do something stupid?
I think you are missing the required field of type Book in Author.
Here's the sample code, which is as per the documentation (tested and works)
class Author {
String name
Book book //you are probably missing this field
static constraints = {
}
}
class Book {
String name
static belongsTo = [author: Author]
static constraints = {
}
}
Test case:
#TestFor(Author)
#Mock([Book])
class AuthorTests {
#Test
void testAuthorBookCascades() {
Author a = new Author(name: "Douglas Adams")
Book b = new Book(name: "So Long, and Thanks for all the Fish")
a.book = b
a.save()
assert Author.count() == 1
assert Book.count() == 1
a.delete()
assert Author.count() == 0
assert Book.count() == 0
}
}
As you can see, you need the Book argument in Author. No need for the hasMany or hasOne clause.