TypeError: The view function did not return a valid response. The function either returned None or ended without a return statement.
视图函数中，没有返回值或返回值缩进不正确。
sqlalchemy.exc.NoReferencedTableError: Foreign key associated with column 'AdminLog.user_id' could not find table 'admin' with which to generate a foreign key to target column 'id'
场景：外键关联，迁移数据库时。
解决方案：将原本Admin类中的__tablename__='Admin'，改为__tablename__='admin'
sqlalchemy.exc.InternalError: (pymysql.err.InternalError) (1050, "Table 'movies' already exists") [SQL: '\nCREATE TABLE `Movies` (\n\tid INTEGER
NOT NULL AUTO_INCREMENT, \n\ttitle VARCHAR(50), \n\tadd_time DATETIME, \n\ttag_id INTEGER, \n\turl VARCHAR(255), \n\tinfo TEXT, \n\tlogo VARCHA
R(255), \n\tarea VARCHAR(50), \n\tlength INTEGER, \n\trelease_time DATE, \n\tstar SMALLINT, \n\tPRIMARY KEY (id), \n\tFOREIGN KEY(tag_id) REFERE
NCES tag (id), \n\tUNIQUE (logo), \n\tUNIQUE (title), \n\tUNIQUE (url)\n)\n\n']
数据库中已存在movies表。（很奇怪为什么migrate的时候还会生成movies的脚本……）将迁移记录删除，重新迁移。