As I'm a bit new to grails, I'm wondering how I can iterate through the current data i have saved in the database to check if the information already exists.
For instance, lets say I have a domain class for Books and I create an action that automatically adds more books but I want to check if the book.title already exists so I don't add it again.
Side note I'm just using the default database (whatever is used when the project is set to production mode)
Edit
I'll post my domains so it is a bit easier to understand. Instead of book.title, I changed it to where book belongs to author. So I only want the author added once but able to add many books for it. The issue happens in an action i created in the controller.
Author Domain:
class Author {
static hasMany = [books:Book]
String authorName
String notes
String age
String toString() { authorName }
static constraints = {
authorName()
notes(maxSize:500)
age()
}
}
Book Domain:
class Book {
static belongsTo = Author
String toString() { bookNumber }
Author bookAuthor
String title
String numberOfPages
static constraints = {
bookAuthor()
title()
numberOfPages()
}
}
Book Controller (this is where I'm having issues):
class BookController {
static allowedMethods = [save: "POST", update: "POST", delete: "POST"]
//took out index, create, list, etc. to focus on the once that I'm concerned about
//this action will simple read a text file and add books and authors
def gather = {
def parseData = new parseClient() //parses text file line by line and puts it into a list
def dataHolder = parseData.information //dataHolder will hold data from text file
int linesOfData = dataHolder.size() //get size to iterate and add authors & books
linesOfData.times {
def _author = dataHolder.author[it] //get author - Author
def _age = dataHolder.age[it] //get age - Author
def _title = dataHolder.title[it] //get title - Book
def _pages = dataHolder.pages[it] //get pages - Book
def authorInstance //create new Author to add
authorInstance = new Author() //for some reason I have to create and save AuthorName (can't have other fields) before I can add my Book correctly
authorInstance.setAuthorName(_author)
authorInstance.save()
def bookInstance
bookInstance = new Book() //create a new Book to add
bookInstance.setBookAuthor(authorInstance)
bookInstance.setTitle(_title)
bookInstance.setNumberOfPages(_pages)
bookInstance.save() //has to have access to the authorInstance to add correctly which is why i was wondering how to access the database to grab it if it existed
authorInstance.setAge(_age) //add whatever data is left for Author
authorInstance.save() //save again because cant save it with this information before I add authorInstance to the Book
}
}
}
Text File Content:
//You'll notice that author _Scott Davis_ is in here twice.
//I don't want to add two instances of Scott Davis but need to access it to add the book
//the unique constraint makes the value come up as not null but can't be added
Scott Davis : Groovy Recipes
Bashar Abdul Jawad : Groovy and Grails Recipes
Fergal Dearle : Groovy for Domain-Specific Languages
Scott Davis : GIS for Web Developers: Adding 'Where' to Your Web Applications
So I'm basically looking for a way to add that information and haven't found a way that seems to work without running into random problems.
Hope this clears my question up a bit, as the original question was a bit broad