I'm getting a strange model error in the final Django challenge. I get the same error in workspaces or on my own desktop.

The issue seems to be with the string representation of the Song class. However this shows up correctly in the admin with the format <title> by <artist>, so I'm not clear what is causing the issue?

Traceback:

ERROR: test_song_string (songs.tests.SongModelTests)

String version of Song should contain the title and artist

Traceback (most recent call last):
File "/home/treehouse/workspace/karaoke/songs/tests.py", line 25, in test_song_string
performer=self.performer)
File "/usr/local/pyenv/versions/3.4.1/lib/python3.4/site-packages/django/db/models/manager.py",
line 127, in manager_method
return getattr(self.get_queryset(), name)(args, **kwargs)
File "/usr/local/pyenv/versions/3.4.1/lib/python3.4/site-packages/django/db/models/query.py", l
ine 346, in create
obj = self.model(*kwargs)
File "/usr/local/pyenv/versions/3.4.1/lib/python3.4/site-packages/django/db/models/base.py", li
ne 480, in init
raise TypeError("'%s' is an invalid keyword argument for this function" % list(kwargs)[0])
TypeError: 'length' is an invalid keyword argument for this function

from django.db import models

# Create your models here.


class Performer(models.Model):
    name = models.CharField(max_length=255)

    def __str__(self):
        return self.name


class Song(models.Model):
    title = models.CharField(max_length=255)
    artist = models.CharField(max_length=255)
    performer = models.ForeignKey(Performer)
    duration = models.IntegerField()

    def __str__(self):
        return '{} by {}'.format(self.title, self.artist)

from django.shortcuts import render

from .models import Song, Performer


# Create your views here.
def song_list(request):
    songs = Song.objects.all()
    context = {'songs': songs }
    return render(request, 'songs/song_list.html', context)


def song_detail(request):
    context = {}
    return render(request, 'songs/song_detail.html', context)


def performer_detail(request):
    performer = Performer.get()
    context = {'performer': performer}
    return render(request, 'songs/performer_detail.html', context)

{% extends 'base.html' %}

{% block title %}{{ performer }}{% endblock %}

{% block content %}
<h2>{{ performer }}</h2>
{% endblock %}