from django.db import models

class Student(models.Model):
    matnr = models.IntegerField(unique=True, verbose_name="Matrikelnummer", help_text='Matrikelnummer wird extern vergeben')
    name  = models.CharField(max_length=64)
    hoert = models.ManyToManyField('Vorlesung', blank=True)
    ANREDE_CHOICES = (
        ('h', 'Herr'),
        ('f', 'Frau'),
        ('d', 'Divers'),
    )
    anrede = models.CharField(max_length=1, blank=True, choices=ANREDE_CHOICES)
    def __str__(self):
        return "%s [%s]" % (self.name, self.matnr)
    class Meta:
        verbose_name        = 'Student'
        verbose_name_plural = 'Studenten'
        ordering            = ('name', 'matnr',)

class Professor(models.Model):
    persnr = models.IntegerField(unique=True)
    name   = models.CharField(max_length=64)
    def __str__(self):
        return "%s [%s]" % (self.name, self.persnr)
    class Meta:
        verbose_name        = 'Professor'
        verbose_name_plural = 'Professoren'
        ordering            = ('name', 'persnr',)

class Vorlesung(models.Model):
    vorlnr = models.IntegerField(unique=True)
    titel  = models.CharField(max_length=128)
    dozent = models.ForeignKey(Professor, null=True, blank=True, on_delete=models.SET_NULL)
    def __str__(self):
        return "%s [%s]" % (self.titel, self.vorlnr)
    class Meta:
        verbose_name        = 'Vorlesung'
        verbose_name_plural = 'Vorlesungen'
        ordering            = ('titel', 'vorlnr',)