title: Grails: Prevent cascading association between two domain classes with multiple relationships
body: <p>Consider two domain classes; Job and Quote.</p>
  
  <p>A Job has many Quotes but a Job also has an accepted quote. The accepted quote is nullable and should only be set once a particular Quote has been accepted by a user. I have the relationships mapped as follows (simplified for the purpose of illustration).</p>
  
  <pre><code>class Job {
      String title
      Quote acceptedQuote   
  }
  
  class Quote {
      Job job
      BigDecimal quoteAmount 
  }
  </code></pre>
  
  <p>The resultant tables are exactly what I require (at least aesthetically) but the problem arises when I go and save a Quote.
  The Quote is saved successfully with a jobId as per the logic in my code but unfortunately the quote's id gets saved in the Job table as the acceptedQuote. Is there anyway to block this cascading association? The code that persists the Quote is fairly basic and looks something like the following;</p>
  
  <pre><code>def quoteInstance = new Quote(job: jobInstance, quoteAmount: amount)
  if (quoteInstance.save(flush: true)) {
     render view: 'show', model: [quoteInstance: quoteInstance]
     break
  }
  </code></pre>
  
  <p>Obviously the jobInstance is passed to the Quote constructor to save an association in the Quote table but I do not know how to prevent the quote Id saving to the job table as the accepted quote.
  Maybe the GORM strategy I am using will not satisfy these requirements?</p>
  
  <p>Any help would be much appreciated.</p>