99 lines
3.1 KiB
Python
99 lines
3.1 KiB
Python
from django.db import models
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from song import Song
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from listfield import IntegerListField
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"""
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Playlist model
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Each playlist is a high-level ordering of songs. That's really it...
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"""
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class Playlist (models.Model):
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"The Playlist class defines the playlist model and its operations"
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name = models.CharField(max_length = 255)
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song_order = IntegerListField()
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#This is a bit of a backup field, since technically the song PK's are in
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#the song_order field. However, it might be useful to just get a reference
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#to the songs in this playlist. Additionally, it's kind of hackish to reference
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#the global Song manager, rather than something that is specific for this playlist.
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songs = models.ManyToManyField(Song)
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def _populate_songs(self):
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"""Make sure that the 'songs' relation is up-to-date."""
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#This operation works by getting the ID's for all songs currently in the playlist,
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#calculates what we need to add, what we need to remove, and then does it.
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#As much work as is possible is done on the python side to avoid the DB
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current_song_ids = [song.id for song in self.songs.all()]
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current_song_ids_set = set(current_song_ids)
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new_song_ids_set = set(song_order)
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remove_set = current_song_ids_set.difference(new_song_ids_set)
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add_set = new_song_ids_set.difference(current_song_ids_set)
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for song_id in remove_set:
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song = self.songs.get(id = song_id)
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song.remove()
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for song_id in add_set:
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song = Song.objects.get(id = song_id) #Using the global Songs manager is unavoidable for this one
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self.songs.add(song)
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def insert(self, position, new_song):
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"""Insert a new song into the playlist at a specific position."""
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if not isinstance(new_song, Song):
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#Not given a song reference, raise an error
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raise ValidationError("Not given a song reference to insert.")
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self.songs.add(new_song)
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self.song_order.insert(position, new_song.id)
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_populate_songs()
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def append(self, new_song):
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"""Add a new song to the end of the playlist."""
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if not isinstance(new_song, Song):
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#Not given a song reference, raise an error
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raise ValidationError("Not given a song reference to insert.")
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self.songs.add(new_song)
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self.song_order.append(new_song.id)
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def move(self, original_position, new_position):
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"""Move a song from one position to another"""
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if original_position == new_position:
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return
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song_id = self.song_order[original_position]
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#This is actually a bit more complicated than it first appears, since the index we're moving to may actually change
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#when we remove an item.
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if new_position < original_position:
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del self.song_order[original_position]
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self.song_order.insert(new_position, song_id)
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else:
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del self.song_order[original_position]
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self.song_order.insert(new_position - 1, song_id) #Account for the list indices shifting down.
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def remove(self, position):
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if position > len(self.song_order):
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return False
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del self.song_order[position]
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def export(self, playlist_type = "m3u"):
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"""Export this internal playlist to a file format."""
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#Default m3u playlist type, support others as I build them.
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if playlist_type = "pls":
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pass
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else:
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#Export m3u, default option
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