CODEWITHSUNDEEP
pythonmysqldjango
Roger Liu
Roger Liu

Reputation: 1898

MySQL foreign key constraint fails in Django app

I'm doing a Django project using MySQL as the database, I have to get some data from another database to fill some fields of my Django database tables.

My Django model for student is like this:

class Student(models.Model):
    #user = models.OneToOneField(User)
    email = models.EmailField(blank=True, null=True)
    email_verified = models.BooleanField(blank=True)
    mobile = models.CharField(max_length=11, unique=True, blank=True, null=True)
    mobile_verified = models.BooleanField(blank=True)

    nickname = models.CharField(max_length=20, blank=True, null=True)
    gender = models.PositiveSmallIntegerField(choices=GENDER_CHOICES,
                                              null=True, blank=True)
    level = models.PositiveSmallIntegerField(choices=STUDENT_LEVELS_CHOICES,
                                             null=True, blank=True)

    source = models.PositiveSmallIntegerField(choices=SOURCE_SITE, blank=True, null=True)
    register_at = models.DateTimeField(blank=True, null=True)
    enroll_at = models.DateTimeField(blank=True, null=True)

    state = models.PositiveSmallIntegerField(choices=STUDENT_MAINTAIN_STATE, blank=True, null=True)
    is_company_user = models.BooleanField(blank=True)
    company_name = models.CharField(max_length=40, blank=True, null=True)
    importance = models.PositiveSmallIntegerField(choices=IMPORTANCE_STATE, blank=True, null=True)
    feature = models.PositiveSmallIntegerField(choices=USER_FEATURE, blank=True, null=True)
    description = models.CharField(max_length=1000, blank=True, null=True)

    sales = models.ForeignKey(User)
    remaining = models.IntegerField(blank=True, null=True)#订单余额
    last_state_change_time = models.DateTimeField(blank=True, null=True)

    is_delete = models.BooleanField(blank=True, default=False)

    objects = StudentManager()

    def __unicode__(self):
        return self.nickname

I wrote a py script to transfer data from another database,the script is:

import MySQLdb

try:
    conn = MySQLdb.connect(host='localhost', user='root', passwd='', db='a')
    cur = conn.cursor()
    cur.execute('select * from student;')
    res = cur.fetchall()
    cur.close()
    conn.close()


    conn = MySQLdb.connect(host='localhost', user='root', passwd='', db='b')
    cur = conn.cursor()
    for item in res:
        if item:
            cur.execute('insert into student_student (email, email_verified, mobile, mobile_verified, nickname, gender, level, register_at) values (%s, %s, %s, %s, %s, %s, %s, %s);', (item[3], item[4], item[1], item[2], item[7], item[8], item[6], item[14]))


    conn.commit()
    cur.close()
    conn.close()



except MySQLdb.Error, e:
    print "Mysql Error %d: %s" % (e.args[0], e.args[1])

My goal is to read the data from "a" to "b", and some field of b could be null (because just a few fields from a is fit for b). And when I run my script, I got the following error:

Mysql Error 1452: Cannot add or update a child row: a foreign key constraint fails (crm.student_student, CONSTRAINT sales_id_refs_id_6e3649f6 FOREIGN KEY (sales_id) REFERENCES auth_user (id))

How to fix this?

I changed my storage engine to be innodb, but it doesn't work.

Upvotes: 2

Views: 7017

Answers (1)

Bibhas Debnath
Bibhas Debnath

Reputation: 14939

sales = models.ForeignKey(User) field is not null and yet when inserting, you're not providing any value to student_student.sales_id. Either provide sales_id or add blank=True and null=True to that field

Upvotes: 2

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