class Book {
   String title
   Date releaseDate
   String author
   static constraints = {
      releaseDate nullable: true
   }
}findWhere
Purpose
Uses named arguments corresponding to domain class property names to execute a query returning the first matching result.
Examples
Given the domain class:
You can query in the form:
def book = Book.findWhere(author: "Stephen King", title: "The Stand")
boolean isReleased = Book.findWhere(author: "Stephen King",
                                    title: "The Stand",
                                    releaseDate: null) != nullDescription
Parameters:
- 
queryParams- AMapof key/value pairs to be used in the query