python - 如何使用 TastyPie 获取 REST Api 中的外键值？

Question

您好，我正在将 Tastypie 与我的 Django 项目一起使用。当我获取与资源api中其他模型有外键关系的模型值时，它返回空值。

我使用 MySql 作为我的数据库。

我的模型代码:

TopicDetail 模型

class Topicdetails(models.Model):
    apptopicid = models.IntegerField(db_column='appTopicID', primary_key=True) # Field name made lowercase.
    portaltopicid = models.IntegerField(db_column='portalTopicID', blank=True, null=True) # Field name made lowercase.
    topicname = models.CharField(db_column='topicName', max_length=500, blank=True) # Field name made lowercase.
    topicshortdescription = models.CharField(db_column='topicShortDescription', max_length=5000, blank=True) # Field name made lowercase.
    class Meta:
        managed = False
        db_table = 'TopicDetails'

讲师详细信息模型

class Instructordetails(models.Model): 
    appinstructorid = models.IntegerField(db_column='appInstructorID', primary_key=True) # Field name made lowercase.
    portalinstructorid = models.IntegerField(db_column='portalInstructorID') # Field name made lowercase.
    firstname = models.CharField(db_column='firstName', max_length=50, blank=True) # Field name made lowercase.
    middlename = models.CharField(db_column='middleName', max_length=50, blank=True) # Field name made lowercase.
    lastname = models.CharField(db_column='lastName', max_length=50, blank=True) # Field name made lowercase.
    optionalid = models.IntegerField(db_column='optionalID', blank=True, null=True) # Field name made lowercase.
    class Meta:
        managed = False
        db_table = 'InstructorDetails'

TopicInstructor Model ，有来自上述两个模型的两个外键。

class Topicinstructor(models.Model):
    topicinstructorrelationid = models.IntegerField(db_column='topicInstructorRelationID', primary_key=True) # Field name made lowercase.
    apptopicid = models.ForeignKey(Topicdetails, db_column='appTopicID') # Field name made lowercase.
    appinstructorid = models.ForeignKey(Instructordetails, db_column='appInstructorID') # Field name made lowercase.
    class Meta:
        managed = False
        db_table = 'TopicInstructor'

还有我的 TopicInstructor api 代码:

class TopicinstructorResource(ModelResource):
    # topicdetails = fields.ForeignKey(TopicdetailsResource,'topicdetails')
    #instructordetails = fields.ForeignKey(InstructordetailsResource, 'instructordetails')
    class Meta:
        queryset = Topicinstructor.objects.all()
        resource_name = 'topicinstructor'
        include_resource_uri = False

如果我从我的资源 api 中取消注释以上两行代码，则会显示错误:

{
error: "The model '<Topicinstructor: Topicinstructor object>' has an empty attribute 'instructordetails' and doesn't allow a null value."
}

当获取资源时，其返回输出如下:

{
meta: {
    limit: 20,
    next: "/api/topicinstructor/?offset=20&limit=20&format=json",
    offset: 0,
    previous: null,
    total_count: 994
    },
objects: [
    {
        topicinstructorrelationid: 1
    },
    {
        topicinstructorrelationid: 2
    },
    {
        topicinstructorrelationid: 3
    },
    {
        topicinstructorrelationid: 4
    },
  ]
}

但我还需要获取外键值。更多关于我使用 python manage.pyspectdb 命令从 MySql 数据库创建了我的模型文件。

请帮助我......

Answer 1

设置null=True，使其允许空值

topicdetails = fields.ForeignKey(TopicdetailsResource,'topicdetails',null=True)
 instructordetails = fields.ForeignKey(InstructordetailsResource,'instructordetails',null=True)