from django.db import models

class Student(models.Model):
    matnr = models.IntegerField(
                unique=True, 
                help_text='MatrNr. wird extern vergeben'
            )
    name  = models.CharField(max_length=64)
    hoert = models.ManyToManyField('Vorlesung', blank=True)
    GECHLECHT_CHOICES = (
            ('h', 'Herr'), 
            ('f', 'Frau'), 
            ('d', 'Divers'),
        )
    geschlecht = models.CharField(max_length=1, null=True, choices=GECHLECHT_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)
    # def get_absolute_url(self):
    #		viewname = 'show_prof'
    #		return reverse(viewname, args=(self.id,) )
    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, 
                on_delete     = models.SET_NULL,
             )
    def __str__(self):
        return "%s [%s]" % (self.titel, self.vorlnr)
    # def get_absolute_url(self):
    #     viewname = 'show_vl'
    #     return reverse(viewname, args=(self.id,) )
    class Meta:
         verbose_name        = 'Vorlesung'
         verbose_name_plural = 'Vorlesungen'
         ordering            = ('titel', 'vorlnr',)