Grails GORM nested has-many relationship query

Question

I try to get all posts that are adressed to an audience containing one specific user by:

StreamPost.findAllByAudience(Friendzone.findAllByFriends(User.findAllById(2)))

or

def posts = StreamPost.where {
    audience.friends.id ==~ userId
}.list()

First results in

ERROR org.hibernate.engine.jdbc.spi.SqlExceptionHelper - No value specified for parameter 1

Second does not work either, returns:

[]

I have the following domain model:

class StreamPost {
    static belongsTo = User
    Friendzone audience

    Date postTimestamp
    String postComment
    String postType

    static constraints = {
        postType inList: ['event','activitylevel','checkin','rating']
    }
}

class Friendzone {
    static belongsTo = User
    static hasMany = [friends:User,
                      streamposts:StreamPost]
    User owner

    String zoneName
    static constraints = {
        owner nullable: false
        friends nullable: false
    }
}

class User {
    static hasMany = [friends:User,
                      friendzones:Friendzone,
                      streamposts:StreamPost]
    static mappedBy  = [ friends: 'friends' ]

    String username
    String password
    boolean enabled = true
    boolean accountExpired
    boolean accountLocked
    boolean passwordExpired

    static constraints = {
        username nullable: false
        password nullable: true
    }
}

So user1 might do a post visible for his friendzone1 which contains user2 and user3. Now I want to get all posts which are visible for user2...

Which ist the best method doing this? dynamic finders, where queries, criteria or hql? How can I avoid previous mentioned errors?

Database scheme:

table: user
id  |  username
1   |  user1
2   |  user2

table: user_friendzone
user_id  |  friendzone_id
2        |  1

table: friendzone
id  |  owner_id  |  zone_name
1   |  1         |  user2only

table: stream_post
id  |  audience_id  |  post_comment
1   |  1            |  comment

Edit 19.08.2015

I think the friendzone class causes the problems. With Emmanuel's comment I figured out that the error (same error as above) is thrown trying to query a friendzone. For example:

def audience = Friendzone.get(1)

Maybe it is the relationship to the "user class"

static belongsTo = User
static hasMany = [friends:User,
                  streamposts:StreamPost]

Answer 1

How about this?

def user = User.get(2)
def audiences = Friendzone.findAllByFriends(user)
def posts = StreamPost.findAllByAudienceInList(audiences)

I wrote it this way to make it easier to read, and to find which query is failing.