使用Flask-SQLAlchemy和Python建模

Question

我最近開始學習Flask，之前曾是C＃開發人員。那麼作爲一個很好的練習，我想創建一個項目，但這次是我以前做過的C＃Webform項目的一個副本。

下面是DB怎麼看起來像在Microsoft SQL

我有一個很難與ORM，並閱讀了一些指南和提示。但是，似乎當我嘗試創建我的項目時，我收到了一些錯誤。下面是模型看起來像在Python

class User(db.Model): 
    __tablename__ = 'users' 
    userID = db.Column(db.Integer, primary_key=True) 
    email = db.Column(db.String(64), unique=True) 
    firstName = db.Column(db.String(64)) 
    lastName = db.Column(db.String(64)) 
    address = db.Column(db.String(64)) 
    zipcode = db.Column(db.Integer, db.ForeignKey('zipcodes.zipcode')) 
    roleID = db.Column(db.Integer, db.ForeignKey('roles.roleID')) 
    password = db.Column(db.String(64)) 

class Role(db.Model): 
    __tablename__ = 'roles' 
    roleID = db.Column(db.Integer, primary_key=True) 
    roleName = db.Column(db.String(64), unique=True, index=True) 

    users = db.relationship('User', backref='role_role') 

class Zipcode(db.Model): 
    __tablename__ = 'zipcodes' 
    zipcode = db.Column(db.Integer, primary_key=True, autoincrement=False) 
    city = db.Column(db.String(64)) 

    users = db.relationship('User', backref='zipcode_zipcode') 


class Artistname(db.Model): 
    __tablename__ = 'artistnames' 
    artistID = db.Column(db.Integer, db.ForeignKey('users.userID'), primary_key=True, autoincrement=False) 
    artistname = db.Column(db.String(64), unique=True) 

    a_users = db.relationship('User', backref='artistname') 

class Act(db.Model): 
    __tablename__ = 'acts' 
    actID = db.Column(db.Integer, primary_key=True) 
    title = db.Column(db.String(64), unique=True) 
    artistID = db.Column(db.Integer, db.ForeignKey('artistnames.artistID')) 
    description = db.Column(db.Text) 
    duration = db.Column(db.Integer) 
    imageURL = db.Column(db.String(64)) 

    a_artistnames = db.relationship('Artistname', backref='act') 

class Performance(db.Model): 
    __tablename__ = 'performances' 
    performanceID = db.Column(db.Integer, primary_key=True) 
    actID = db.Column(db.Integer, db.ForeignKey('acts.actID')) 
    date = db.Column(db.Date) 
    stageID = db.Column(db.Integer, db.ForeignKey('stages.stageID')) 

class Stage(db.Model): 
    __tablename__ ='stages' 
    stageID = db.Column(db.Integer, primary_key=True) 
    stageName = db.Column(db.String(64)) 

我不知道，如果你需要一點點數據庫描述，但這裏有雲，如果你需要它。

數據庫描述

市 與城市的名稱和相應的郵政編碼的表。

角色 包含用於用戶的角色名稱和相應角色ID的表。

用戶 的表與用戶

ARTISTNAME 如果用戶是有作用（artistuser），所以我用這個表中的所有數據是誰需要一個用戶名的用戶。當連接ArtistID =用戶名看到T-SQL它會是什麼樣子的MS數據庫，如果你需要參考

法 一個表，其中顯示了連接是從ARTISTNAME行爲， ArtistID = ArtistID看看誰做的行爲

性能 時的行爲是滾動，例如動作1，顯示錶是現場週一至週五。

階段 一個表格，顯示演奏的位置。

的錯誤

那麼當我運行這段代碼（我成功地插入到兩個表，角色和郵編）。但是，當我嘗試插入第三個表時， - 用戶我收到錯誤。 如何插入

# Role 
    r1 = Role(roleName='Role 1') 
    r2 = Role(roleName='Role 2') 
    r3 = Role(roleName='Role 3') 
    db.session.add_all([r1, r2, r3]) 

    # Zipcode 
    zip1 = Zipcode(zipcode=1, city='zip 1') 
    zip2 = Zipcode(zipcode=2, city='zip 2') 
    zip3 = Zipcode(zipcode=3, city='zip 3') 
    db.session.add_all([zip1, zip2, zip3]) 

    # User 
    u1 = User(
     email='a@a.dk', 
     firstName='John', 
     lastName='Doe', 
     address='test street 1', 
     zipcode=zip2, 
     roleID=r1, 
     password='john') 
    u2 = User(
     email='b@b.dk', 
     firstName='Jane', 
     lastName='Doe', 
     address='test street 1', 
     zipcode=zip1, 
     roleID=r2, 
     password='jane') 
    u3 = User(
     email='c@c.dk', 
     firstName='Jack', 
     lastName='Doe', 
     address='test street 1', 
     zipcode=zip3, 
     roleID=r3, 
     password='jack') 

    db.session.add_all([u1, u2, u3]) 

    # commit db 
    db.session.commit() 

和我得到

Traceback (most recent call last): 
    File "<console>", line 1, in <module> 
    File "C:\var\test\las_vegas\__program\test.py", line 52, in t 
    db.session.commit() 
    File "C:\var\test\las_vegas\lib\site-packages\sqlalchemy\orm\scoping.py", line 
149, in do 
    return getattr(self.registry(), name)(*args, **kwargs) 
    File "C:\var\test\las_vegas\lib\site-packages\sqlalchemy\orm\session.py", line 
768, in commit 
    self.transaction.commit() 
    File "C:\var\test\las_vegas\lib\site-packages\sqlalchemy\orm\session.py", line 
370, in commit 
    self._prepare_impl() 
    File "C:\var\test\las_vegas\lib\site-packages\sqlalchemy\orm\session.py", line 
350, in _prepare_impl 
    self.session.flush() 
    File "C:\var\test\las_vegas\lib\site-packages\sqlalchemy\orm\session.py", line 
1907, in flush 
    self._flush(objects) 
    File "C:\var\test\las_vegas\lib\site-packages\sqlalchemy\orm\session.py", line 
2025, in _flush 
    transaction.rollback(_capture_exception=True) 
    File "C:\var\test\las_vegas\lib\site-packages\sqlalchemy\util\langhelpers.py", 
line 57, in __exit__ 
    compat.reraise(exc_type, exc_value, exc_tb) 
    File "C:\var\test\las_vegas\lib\site-packages\sqlalchemy\util\compat.py", line 
172, in reraise 
    raise value 
    File "C:\var\test\las_vegas\lib\site-packages\sqlalchemy\orm\session.py", line 
1989, in _flush 
    flush_context.execute() 
    File "C:\var\test\las_vegas\lib\site-packages\sqlalchemy\orm\unitofwork.py", l 
ine 371, in execute 
    rec.execute(self) 
    File "C:\var\test\las_vegas\lib\site-packages\sqlalchemy\orm\unitofwork.py", l 
ine 524, in execute 
    uow 
    File "C:\var\test\las_vegas\lib\site-packages\sqlalchemy\orm\persistence.py", 
line 64, in save_obj 
    mapper, table, insert) 
    File "C:\var\test\las_vegas\lib\site-packages\sqlalchemy\orm\persistence.py", 
line 600, in _emit_insert_statements 
    execute(statement, params) 
    File "C:\var\test\las_vegas\lib\site-packages\sqlalchemy\engine\base.py", line 
727, in execute 
    return meth(self, multiparams, params) 
    File "C:\var\test\las_vegas\lib\site-packages\sqlalchemy\sql\elements.py", lin 
e 322, in _execute_on_connection 
    return connection._execute_clauseelement(self, multiparams, params) 
    File "C:\var\test\las_vegas\lib\site-packages\sqlalchemy\engine\base.py", line 
824, in _execute_clauseelement 
    compiled_sql, distilled_params 
    File "C:\var\test\las_vegas\lib\site-packages\sqlalchemy\engine\base.py", line 
954, in _execute_context 
    context) 
    File "C:\var\test\las_vegas\lib\site-packages\sqlalchemy\engine\base.py", line 
1119, in _handle_dbapi_exception 
    util.reraise(*exc_info) 
    File "C:\var\test\las_vegas\lib\site-packages\sqlalchemy\util\compat.py", line 
172, in reraise 
    raise value 
    File "C:\var\test\las_vegas\lib\site-packages\sqlalchemy\engine\base.py", line 
947, in _execute_context 
    context) 
    File "C:\var\test\las_vegas\lib\site-packages\sqlalchemy\engine\default.py", l 
ine 435, in do_execute 
    cursor.execute(statement, parameters) 
    File "C:\var\test\las_vegas\lib\site-packages\pymysql\cursors.py", line 130, i 
n execute 
    query = query % self._escape_args(args, conn) 
    File "C:\var\test\las_vegas\lib\site-packages\pymysql\cursors.py", line 96, in 
_escape_args 
    return tuple(conn.escape(arg) for arg in args) 
    File "C:\var\test\las_vegas\lib\site-packages\pymysql\cursors.py", line 96, in 
<genexpr> 
    return tuple(conn.escape(arg) for arg in args) 
    File "C:\var\test\las_vegas\lib\site-packages\pymysql\connections.py", line 69 
0, in escape 
    return escape_item(obj, self.charset) 
    File "C:\var\test\las_vegas\lib\site-packages\pymysql\converters.py", line 24, 
in escape_item 
    encoder = encoders[type(val)] 
KeyError: <class 'manage.Zipcode'> 

額外

插入用戶與ARTISTNAME在MS

ALTER PROCEDURE [dbo].[sp_INSERT_MAGICIAN] 
    @newArtistName nvarchar(50), 
    @newFirstName nvarchar(50), 
    @newLastName nvarchar(50), 
    @newEmail nvarchar(50), 
    @newPassword varchar(50), 
    @newAddress nvarchar(50), 
    @newZipcode int 
AS 
    declare @inserr int 
    declare @maxerr int 

    set @maxerr = 0 

BEGIN TRANSACTION 

--add user 
INSERT INTO [User] 
    ([User].Firstname, [User].Lastname, [User].Email, [User].[Password], [User].[Address], [User].Zipcode, [User].[Role]) 
VALUES 
    (@newFirstName, @newLastName, @newEmail, @newPassword, @newAddress, @newZipcode, 3) 

INSERT INTO [Artistname]  
    ([Artistname].ArtistId, [Artistname].Artistname) 
VALUES 
    (SCOPE_IDENTITY(), @newArtistName) 

-- Save error number returned from Insert statement 
SET @inserr = @@error 
IF @inserr > @maxerr 
    SET @maxerr = @inserr 

-- If an error occured, roll back 
IF @maxerr <> 0 
    BEGIN 
     rollback transaction 
     print 'Transaction rolled back' 
    END 
ELSE 
    BEGIN 
     COMMIT transaction 
     PRINT 'Transaction comimitted' 
    END 
PRINT 'INSERT error number:' + cast(@inserr as nvarchar(8)) 

RETURN @maxerr 

錯誤

Answer 1

您需要在用戶使用它們之前提交角色和郵政編碼。這些對象在該點之前不會有整數ID。您還必須將用戶對象更改爲像

u1 = User(
    email='a@a.dk', 
    firstName='John', 
    lastName='Doe', 
    address='test street 1', 
    zipcode=zip2.zipcode, 
    roleID=r1.roleID, 
    password='john') 

郵政編碼和角色字段期望整數ids，而不是對象。