Django生成相反模型列表

Question

我正试图开发一个程序，将确定哪些植物对其他植物有益和有害。我希望它能够遍历一个植物列表，比较并查看一种植物的detis_insects_and_imports物种是否与另一种植物的pestors，然后它将其添加到ally_dete_pests_for(self):中的列表。

     class AnimalSpecies(models.Model):
            common_name = CharField(max_length = 200, null = True, blank = True)
            scientific_name = CharField(max_length = 200, null = True, blank = True)
        
            genus = Foreign

Key(Genus, null = True, blank = True, on_delete = models.CASCADE)
        class Meta:
            verbose_name = "Animal Species"
            verbose_name_plural = "Animal Species"
        def __str__(self):
            return self.common_name
    #___________________________________________________________________________________Begin Species_______________________________________________
    class PlantSpecies(models.Model):
        #________________________Name & Relationships________________________
        common_name = CharField(max_length = 200, null = True, blank = True)
        species_name = CharField(max_length = 200, null = True, blank = True)
        genus = ForeignKey(Genus, blank = True, null =True, on_delete = models.CASCADE)
        rotation_family = ForeignKey(RotationFamily, blank = True, null = True, on_delete = models.CASCADE)
    
        #________________________Growth & Environment________________________
        annual = BooleanField(null = True, blank = True)
        GROWTH_HABIT_LIST = [
            ("H", "Herb"),
            ("S", "Shrub"),
            ("T", "Tree"),
            ("U", "Succulent"),
            ("G", "Grass"),
            ("F", "Fern"),
            ("V", "Vine")
        ]
        growth_habit = CharField(max_length = 20, blank = True, null = True, choices = GROWTH_HABIT_LIST)
        pruning = TextField(max_length = 1000, null = True, blank = True)
        days_to_germinate = IntegerField(null = True, blank = True, default = 0)
        days_to_maturity = IntegerField(null = True, blank = True, default = 0)
        zone = IntegerField(null = True, blank = True, default = 0)
    
        SUN_REQUIREMENT_LIST = [
            ("FH", "Full Shade"),
            ("FHPH", "Full Shade-Partial Shade"),
            ("PHFS", "Partial Shade-Full Sun"),
            ("FS", "Full Sun")
        ]
        sun_requirement = CharField(max_length = 200, null = True, blank = True, choices = SUN_REQUIREMENT_LIST)
        WATER_REQUIREMENT_LIST = [
            ("M", "Mesic"),
        ]
        water_requirement = CharField(max_length = 20, null = True, blank = True, choices = WATER_REQUIREMENT_LIST)
    
    
        pollinator = ManyToManyField(AnimalSpecies, blank = True, related_name = "pollinators")
        beneficials = ManyToManyField(AnimalSpecies, blank = True, related_name = "beneficials")
        pests = ManyToManyField(AnimalSpecies, blank = True, related_name = "Pests")
    
        deters_insect_and_animals = ManyToManyField(AnimalSpecies, blank = True, related_name = "deters_AnimalSpecies")
        
        #________________________Spacing________________________
        number_per_square_foot = IntegerField(null = True, blank = True, default = 0)
        spacing_inches = FloatField(max_length = 200, null = True, blank = True, default = 0)
        spread_inches = FloatField(max_length = 200, null = True, blank = True, default = 0)
        height = IntegerField(null = True, blank = True, default = 0)
        #________________________Yield________________________
        expected_yield_pounds = FloatField(max_length = 200, blank = True, null = True, default = 0)
        expected_pound_per_fruit = FloatField(max_length = 200, blank = True, null = True, default = 0)
        #________________________Description________________________
        COLOR_CHOICES = [
            ("RE", "Red"),
            ("OR", "Orange"),
            ("YE", "Yellow"),
            ("LGR", "Light Green"),
            ("GR", "Green"),
            ("DGR", "Dark Green"),
            ("BL", "Blue"),
            ("PU", "Purple"),
            ("PI", "Pink"),
            ("WH", "White")
        ]
       
        
        foliage_color = CharField(max_length = 20, null = True, blank = True, choices = COLOR_CHOICES)
        flower_color = CharField(max_length = 20, null = True, blank = True, choices = COLOR_CHOICES)
        fruit_color = CharField(max_length = 20, null = True, blank = True, choices = COLOR_CHOICES)
    
        PARTS_CHOICES = [
            ("FLRW", "Fruit, Leaves, Roots, Flowers"),
            ("FLW", "Fruit, Leaves, Flowers"),
            ("FR", "Fruit, Roots, Flowers"),
            ("LR", "Leaves, Roots, Flowers"),
            ("LRW", "Leaves, Roots, Flowers"),
            ("FL", "Fruit, Leaves"),
            ("FR", "Fruit, Roots"),
            ("LR", "Leaves, Roots"),
            ("F", "Fruit"),
            ("L", "Leaves"),
            ("R", "Roots"),
            ("W", "Flowers"),
            ("O", "Other"),
            ("N", "None")
        ]
        edible_parts = CharField(max_length = 20, null = True, blank = True, choices = PARTS_CHOICES)
        toxic_parts = CharField(max_length = 20, null = True, blank = True, choices = PARTS_CHOICES)
        @property
        def improves_growth_and_flavor(self):
            return ManyToManyField(self, blank = True, related_name = "improves_growth")
        
        @property
        def improves_health_and_flavor(self):
            return ManyToManyField(self, blank = True, related_name = "improves_health")
        @property
        def impairs_health_and_growth(self):
            return ManyToManyField(self, blank = True, related_name = "impairs_health")
            
        @property
        def visual_name(self):
            return f"{self.rotation_family.visual_color}{self.common_name}"
        visual_name.fget.short_description = "Name"
        @property
        def scientific_name(self):
            return f"{self.genus.scientific_name} {self.species_name}"
        @property
        def expected_fruit_yield(self):
            try:
                return self.expected_yield_pounds / self.expected_pound_per_fruit
            except:
                return "0"
    
        @property
        def ally_deter_pest_for(self):
            x = []
            y = PlantSpecies.objects.filter(self.pests)
            for i in range(len(self.deters_insect_and_animals)):
                for h in range(len(y)):
                    if self.deters_insect_and_animals[i] == y[h]:
                        x.append(f"{y[h].common_name} | {self.deters_insect_and_animals[i]}")
                    else:
                        pass
            return x

内部服务器错误：/admin/gardenapp/plantmonics/Traceback（最近的调用为last）：文件“C:\users\deant\appdata\local\programs\python\python39\lib\site-packages\django\db\models\options.py”，第575行，在get_field返回self.fields_map[field_name]键错误：“ally_dete_pest_for”

在处理上述异常的过程中，发生了另一个异常：

回溯（最近的调用最后）：文件“C:\users\deant\appdata\local\programs\python\python39\lib\site-packages\django\contrib\admin\utils.py”,第265行，在lookup_field f=_get_non_gfk_field（opts,name）文件“b\site-packages\django\db\models\options.py”，第577行，在get_field中引发fielddoesnotext（“%s没有名为'%s'的字段”%(self.object_name,field_name))django.core.exceptions.fielddoesnotext：plantvements没有名为'ally_dete_pest_for'的字段

在处理上述异常的过程中，发生了另一个异常：

Answer 1

您首先需要获得所有相关的对象。

for i in range(len(self.deters_insect_and_animals.all())):
    # further code

参考：ManyToMany关系