Django admin-外键显示其值（非内联）

Question

earlier this week, I asked this question about having foreign keys in your main model from your subclasses: Django Form With Foreign Key

I used the answer given to make a model and sub-models (code at the end). My question is, I know about admin inlines for foreign keys, but I can't use that since the main model has the foreign key to the subclasses, not the other way around. I want the foreign keys in my main class to be displayed in the admin.

Sorry it that sounds confusing, here's my model:

Subclass 1 PreObservation

class PreObservation( models.Model ):                                
    pre_observation = models.CharField(                              
                        max_length=255,                          
                        choices=OBS_STANDARD_TYPES,              
                        verbose_name="Pre-Observation Standard"  
                    )                                            
    obs__meter_reading = models.FloatField( blank=True, null=True )  
    obs_if_other = models.FloatField( blank=True, null=True )        

Subclass 2 FieldObservation

class FieldObservation( models.Model ):                                                          
      site_id = models.CharField( max_length=255, choices=STATION_CHOICES )                        
      site_name = models.CharField( max_length=255 )                                               
      stage_reading = models.FloatField( )                                                         
      specific_conductance = models.FloatField( )                                                  
      water_temp = models.FloatField( )                                                            

Main class Record

class Record( models.Model ):                                                                    
      observers = models.CharField( max_length=255, verbose_name="Name of Observer(s)")            

      pre_observation_standard_1 = models.ForeignKey(                                              
                                 PreObservation,                                              
                                 related_name="pre_observation_1"                             
                             )                                                                
      pre_observation_standard_2 = models.ForeignKey(                                              
                                 PreObservation,                                              
                                 related_name="pre_observation_2",                            
                                 blank=True, null=True                                        
                             )                                                                

      field_observation_1 = models.ForeignKey(                                                     
                         FieldObservation,                                                    
                         related_name="field_observation_1"                                   
                       )                                                                      
      field_observation_2 = models.ForeignKey(                                                     
                         FieldObservation,                                                    
                         related_name="field_observation_2",                                  
                         blank=True, null=True                                                
                       )                                                                      

      cloud_coverage = models.CharField( max_length=255, choices=CLOUD_COVERAGE )                  
      rain_past_three_days = models.BooleanField( verbose_name="Rain in Past 3 Days" )             
      snow = models.BooleanField( )                                                                
      snow_melt = models.FloatField( )                                                             
      temperature = models.CharField( max_length=255, choices=TEMPERATURE )                        
      wind = models.CharField( max_length=255, choices=WIND )                                      
      field_notes = models.TextField( )                                                            
      teachers_comments = models.TextField( )                                                      

      user = models.ForeignKey( User )                                                             
      group_name = models.CharField( max_length=255, blank=True )                                  

Answer 1

You can use

  class RecordAdmin(admin.ModelAdmin):
  list_display = ('pre_observation__pre_observation_standard_1', 
                'pre_observation__pre_observation_standard_2', )

  admin.site.register(Record, RecordAdmin)