Django获取Comment对象时如何获取外键commentGroup的commentGroupDesc字段

我需要从Comment模型的外键关联对象中获取commentGroupDesc字段，目前已经能正常获取到commentGroup，但需要该字段值用于表单填充。

相关代码 #

models.py

class commentGroup (models.Model):
        commentGroup = models.CharField(_("commentGroup"), primary_key=True, max_length=255)
        commentGroupDesc = models.CharField(_("commentGroupDesc"),null=True, blank=True, max_length=255)
        def __str__(self):
            return str(self.commentGroup)
        class Meta:
            ordering = ['commentGroup']
class Comment (models.Model):
        commentID = models.AutoField(_("commentID"),primary_key=True)
        commentUser = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.CASCADE)
        commentGroup = models.ForeignKey(commentGroup, on_delete=models.CASCADE,  null=True)
        commentCI = models.ForeignKey(Servicenow, on_delete=models.CASCADE,  null=True)
        commentText = RichTextField(_("commentText"), null=True, blank=True)
        commentTableUpdated = models.CharField(_("commentTableUpdated"), null=True, blank=True, max_length=25)
        def __str__(self):
            return str(self.commentGroup)
        class Meta:
            ordering = ['commentGroup']

views.py

comment = Comment.objects.get(pk=commentID)

解决方案 #

comment作为Comment的实例，它的commentGroup属性直接指向关联的commentGroup对象，通过链式访问即可拿到目标字段：

# 确认comment.commentGroup不为空时直接获取
comment_group_desc = comment.commentGroup.commentGroupDesc

# 若commentGroup可能为null，为避免触发AttributeError，可做空值判断
comment_group_desc = comment.commentGroup.commentGroupDesc if comment.commentGroup else ""
# 或者用getattr处理默认值
comment_group_desc = getattr(comment.commentGroup, 'commentGroupDesc', "")

拿到该字段值后即可直接用于表单填充。

内容的提问来源于stack exchange，提问作者user625079