单元测试 - 类型错误："dict"对象不可调用

Question

我是数据库的新手，所以很抱歉，如果这个问题太基础了。

我正在尝试测试与Track模型有关系的Playlist模型。

class Track(db.Model):
    """
    Model for storing track information
    """
    id = db.Column(db.Integer, primary_key=True)
    artist = db.Column(db.String(140))
    title = db.Column(db.String(140))
    created = db.Column(db.DateTime, default=func.now())
    track_id = db.Column(db.String(140))
    tempo = db.Column(db.Float)      
    user_id = db.Column(db.Integer, db.ForeignKey('users.id'))
    def __init__(self, title, artist, uri):
        self.title = title
        self.artist = artist
        self.uri = uri
    @property
    def serialize(self):
       """Return object data in easily serializeable format"""
       return {
           'id' : self.id,
           'title': self.title,
           'artist': self.artist,
           'track_id': self.track_id,
            'tempo':self.tempo
       } 

然后我有这个辅助表：

tracks = db.Table('tracks',
    db.Column('track_id', db.Integer, db.ForeignKey('track.id')),
    db.Column('playlist_id', db.Integer, db.ForeignKey('playlist.id')))

在这里，Playlist模型：

class Playlist(db.Model):
    """
    Model for storing playlist information belonging to a specific user
    """
    __tablename__ = 'playlist'
    id = db.Column(db.Integer, primary_key=True)
    title = db.Column(db.String(50))
    created = db.Column(db.DateTime, default=func.now())    
    user_id = db.Column(db.Integer, db.ForeignKey('users.id'))
    tracks = db.relationship('Track', 
                            secondary=tracks,
                            backref=db.backref('playlists', 
                            lazy='dynamic'))
    def __init__(self, title):
        self.title = title
    @property
    def serialize(self):
       """Return object data in easily serializeable format"""
       return {
           'id' : self.id,
           'created' : self.created,
           'title': self.title,
           'tracks': [ item.serialize for item in self.tracks]
       }

现在我正在尝试测试Playlist，如下所示：

test_playlist_model.py

import unittest
# third party libs
from sqlalchemy.exc import IntegrityError
# application modules
from project.api.models.base import db
from project.api.models.all import Playlist, tracks
from project.tests.base import BaseTestCase
from project.tests.utils import add_playlist

class TestPlaylistModel(BaseTestCase):
    def test_add_track(self):
        track = add_track(title='Karma Police',
                          artist='Radiohead',
                          uri='spofity:test')
        self.assertEqual(track.title, 'Karma Police')
        self.assertEqual(track.artist, 'Radiohead')
        self.assertEqual(track.uri, 'spofity:test')

    def test_add_playlist(self):
        track = add_track(title='Karma Police',
                          artist='Radiohead',
                          uri='spofity:test')
        playlist = add_playlist(title='Alternative')
        self.assertEqual(playlist.title, 'Alternative')
        self.assertTrue(playlist.id)
        self.assertEqual(playlist.tracks, track.serialize())
if __name__ == '__main__':
    unittest.main()

utils.py

from project.api.models.base import db
from project.api.models.all import Playlist
def add_playlist(title):
    playlist = Playlist(
        title=title)
    db.session.add(playlist)
    db.session.commit()
    return playlist
def add_track(title, artist, uri):
    track = Track(
                title=title,
                artist=artist,
                uri=uri
            )
    db.session.add(track)
    db.session.commit()
    return track

但我得到：

======================================================================
ERROR: test_add_playlist (test_playlist_model.TestPlaylistModel)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/usr/src/app/project/tests/test_playlist_model.py", line 34, in test_add_playlist
    self.assertEqual(playlist.tracks, track.serialize())
TypeError: 'dict' object is not callable

我错过了什么？

Answer 1

您的方法Track.serialize实际上是一个属性，这意味着当您访问字典时，它会像属性一样返回字典。

您应该在track.serialize后删除括号(并考虑将属性重命名为 track.serialized以避免混淆(或删除@property修饰器。

---

class Playlist(db.Model):
    ...
    def serialize(self):
        ...

class Track(db.Model):
    ...
    def serialize(self):
        ...