please help with null exception when adding data with grails

I am trying to add data to a database, in grails but get this error:

Error 500: Executing action [getData] of controller [mgr.CollectDataEntryController] caused exception: groovy.lang.MissingMethodException: No signature of method: static groovy.lang.MissingMethodException.addToAlumConnectionEducations() is applicable for argument types: (mgr.AlumConnectionEducations) values: [mgr.AlumConnectionEducations : null]

where CollectDataEntryController is the controller doing the work. here is the code snippet from that controller:

saveNewAlum.addToAlumConnectionEducations(new AlumConnectionEducations(alumConnectionsId:connectionId, degree:alumConnectionEduDegree,endDate:alumConnectionEduEndDate,fieldOfStdudy:alumConnectionEduFieldOfStudy,schoolName:alumConnectionEduSchoolName,startDate:alumConnectionEduStartDate))

the domain, AlumConnectionEducations , belongs to a one to many relationship with another domain, AlumConnections, which in turn belongs to a one-to-many relationship with to another domain, alumProfile

to, in my code I first add the domain AlumConnection, which works fine but when i then try to add AlumConnectionEducations i get the above error. anyone have any idea of what i am d开发者_运维技巧oing wrong?

thanks jason

    package mgr
    import java.util.Date;
    class AlumConnections  {
String linkedinId
String firstName
String lastName
String headline
String locationName
String locationCode
String industry
    Date dateCreated
Date lastUpdated
long version
static belongsTo = [alumProfile:AlumProfile]
static hasMany = [  
alumConnectionEducations    :   AlumConnectionEducations
 ]
static mapping = {
    cache true

    columns {       
        linkedinId      type:'text'
        firstName       type:'text'
        lastName        type:'text'
        headline        type:'text'
        locationName    type:'text'
        locationCode    type:'text'
        industry        type:'text'

    }
}
static constraints = {  
    linkedinId      (nullable:false, blank:false)
    firstName       (nullable:true)
    lastName        (nullable:true)
    headline        (nullable:true)
    locationName    (nullable:true)
    locationCode    (nullable:true)
    industry        (nullable:true)

}
  }         

in the controller that calls the domains:

  def saveNewAlum = ""
  saveNewAlum = new AlumProfile(firstName:linkedinFirstName, lastName:linkedinLastName, dob:newDate,industry:linkedinIndustry, oAuthToken:oAuthtoken, secretKey:secretKey)

  saveNewAlum.addToAlumConnections(new   AlumConnections(linkedinId:connectionId,firstName:connectionFName, lastName:connectionLName, headline:connectionHeadline, locationName:connectionLocationname, locationCode:connectionLocationCode,industry:connectionIndustry))

The above code works fine and saves to the MySQL database. its only when i try to create saveNewAlum.addToAlumConnectionEducations that i get the error

---

well, it took all day but i got it. so, my assumption seemed to be right, it was the one-to-many with a one-to-many that was causing the problem. here's how i fixed it. The domains were right the way i had it. in the controller: first, i create the main parent:

         saveNewAlum=new AlumProfile(firstName:linkedinFirstName, lastName:linkedinLastName, dob:newDate, industry:linkedinIndustry, oAuthToken:oAuthtoken, secretKey:secretKey)

then, i create the object to be added to the child:

     myConnection= new AlumConnections(linkedinId:connectionId,firstName:connectionFName,lastName:connectionLName,headline:connectionHeadline,locationName:connectionLocationname, locationCode:connectionLocationCode,industry:connectionIndustry)

then, i save the child to the parent:

    saveNewAlum.addToAlumConnections(myConnection)

then, i create the object to save to the child's child:

  newConnectionEdu=  new AlumConnectionEducations(
              degree:alumConnectionEduDegree,
              endDate:alumConnectionEduEndDate,
              fieldOfStudy:alumConnectionEduFieldOfStudy,
              schoolName:alumConnectionEduSchoolName,
              startDate:alumConnectionEduStartDate)

then, finally, i add the child to the child:

 myConnection.addToAlumConnectionEducations(newConnectionEdu)

and that is how you add a child to a child!