Subclass F objects to provide JSONB field access in Django 1.8+

extensions.py

from django.db.models import F                                                                      
                                                                                                    
# Needs expansion but may eventually allow things like:                                             
# recs = Record.objects.annotate(num_killed=JBF('data').jbPath(Value("{Accident Details, Number killed}"))).filter(num_killed__asint=1)
                                                                                                    
class JBF(F):                                                                                       
    JB_PATH = '#>'                                                                                  
    JB_PATH_STR = '#>>'                                                                             
    JB_FIELD = '->'                                                                                 
    JB_FIELD_STR = '->>'                                                                            
    JB_ELEM = '->'                                                                                  
    JB_ELEM_STR = '->'                                                                              
                                                                                                    
    def jbPath(self, other):                                                                        
        return self._combine(other, self.JB_PATH, False)                                            
                                                                                                    
    def jbPathStr(self, other):                                                                     
        return self._combine(other, self.JB_PATH_STR, False)