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python - 自动映射的通用数据模型架构上的 SQLAlchemy 级联删除

问题描述

我有一个来自 OfBiz 安装的预定义 PostgreSQL 数据库。该数据库有许多外键组件。我正在尝试编写一个 python 程序来将数据从生产数据库复制到登台或开发数据库中。

最后一步是从我的数据集中清除一些开发人员不应该看到的私有数据。

我的反射设置如下：

def reflectSourceTables():
     global Base
     Base = automap_base(metadata = smeta)
     global baseNum
     baseNum = 0
     Base.prepare(name_for_collection_relationship=_name_for_collection_relationship, name_for_scalar_relationship=_name_for_scalar_relationship, generate_relationship=_generate_relationship)

我的反射设置如下

def _name_for_scalar_relationship(base, local_cls, referred_cls, constraint):
    global baseNum
    if constraint.name:
        baseNum += 1
        disc = '_'.join(col.name for col in constraint.columns)
        return referred_cls.__name__.lower() + '.' + disc + "_scalar_" + str(baseNum)
    # if this didn't work, revert to the default behavior
    return name_for_scalar_relationship(base, local_cls, referred_cls, constraint)

def _name_for_collection_relationship(base, local_cls, referred_cls, constraint):
    global baseNum
    if constraint.name:
        baseNum += 1
        
        disc = '_'.join(col.name for col in constraint.columns)
        return referred_cls.__name__.lower() + '.' + disc + "_collection_" + str(baseNum)
    
    # if this didn't work, revert to the default behavior
    return name_for_collection_relationship(base, local_cls, referred_cls, constraint)

def _generate_relationship(base, direction, return_fn, attrname, local_cls, referred_cls, **kw):
    
    if direction is interfaces.ONETOMANY:
        kw['cascade'] = 'all, delete-orphan'
        kw['passive_deletes'] = True
    
    return generate_relationship(base, direction, return_fn, attrname, local_cls, referred_cls, **kw)

我可以使用以下代码查看表之间的关系：

def getTableList(smeta):
    tableList = []
    if args.tables:
        ##Validate tables are in database
        for table in args.tables:
            if smeta.tables[table] in smeta.sorted_tables:
                tableList.append(str(smeta.tables[table]))
            else:
                log('Table {0} does not exist on source'.format(table))
    else:
        tableList = smeta.sorted_tables
    
    if args.tables:
        for table in tableList:
            
            for relationship in getattr(Base.classes,str(table)).__mapper__.relationships:
                #print(relationship)
                tableName = re.search(r'\.(.*)\.', str(relationship)).group(1)
                if tableName and tableName not in tableList:
                    tableList.append(tableName)
            
    return tableList

但我希望删除代码：

def cleanData():
    log("Clean Data")
    destSession = sessionmaker()
    destSess = destSession(bind=db2)
    
    for partyId in partyIds:
        log("Cleaning data for {0}".format(partyId))
        voucher = Base.classes.voucher
        invoice = Base.classes.invoice
        voucherDelete = destSess.query(voucher).filter_by(party_id=partyId)
        voucherDelete.delete(synchronize_session=False)
        invoiceDelete = destSess.query(invoice).filter_by(party_id_from=partyId)
        invoiceDelete.delete(synchronize_session=False)
        destSess.commit()

删除确实会删除凭证和发票，但不会删除子 invoice_item 记录。

我的数据库设置不包括外键的级联删除功能，但我希望我可以让 ORM 提供该功能。

理想情况下，此代码将删除凭证或发票的子代。

编辑

新的关系生成如下：

def _generate_relationship(base, direction, return_fn, attrname, local_cls, referred_cls, **kw):
## Write this to include cascade delete see: https://docs.sqlalchemy.org/en/latest/orm/extensions/automap.html#custom-relationship-arguments
if direction is interfaces.ONETOMANY or direction is interfaces.MANYTOMANY:
    kw['cascade'] = 'all, delete, delete-orphan'
    kw['passive_deletes'] = False

if direction is interfaces.MANYTOONE:
    kw['viewonly'] = True
    
return generate_relationship(base, direction, return_fn, attrname, local_cls, referred_cls, **kw)

删除代码更改为：

voucher = Base.classes.voucher
    invoice = Base.classes.invoice
    invoiceDelete = destSess.query(invoice).filter_by(party_id_from=partyId)
    rs = invoiceDelete.all()
    for result in rs:
        destSess.delete(result)
    voucherDelete = destSess.query(voucher).filter_by(party_id=partyId)
    rs = voucherDelete.all()
    for result in rs:
        destSess.delete(result)
    destSess.commit()

这会导致以下错误：

sqlalchemy.exc.IntegrityError: (psycopg2.IntegrityError) update or delete on table "invoice_item" violates foreign key constraint "invoice_imat_itm" on table "invoice_item_attribute"
DETAIL:  Key (invoice_id, invoice_item_seq_id)=(19439, 00001) is still referenced from table "invoice_item_attribute".
 [SQL: 'DELETE FROM invoice_item WHERE invoice_item.invoice_id = %(invoice_id)s AND invoice_item.invoice_item_seq_id = %(invoice_item_seq_id)s'] [parameters: ({'invoice_id': '19439', 'invoice_item_seq_id': '00001'}, {'invoice_id': '33674', 'invoice_item_seq_id': '00001'}, {'invoice_id': '49384', 'invoice_item_seq_id': '00001'}, {'invoice_id': '58135', 'invoice_item_seq_id': '00001'}, {'invoice_id': '83457', 'invoice_item_seq_id': '00001'})] (Background on this error at: http://sqlalche.me/e/gkpj)

标签： pythonpostgresqlsqlalchemyofbiz

解决方案

以下配置允许我在我的数据库中删除凭证和发票的子记录。

关系自动映射器设置如下：

def _generate_relationship(base, direction, return_fn, attrname, local_cls, referred_cls, **kw):
    ## Write this to include cascade delete see: https://docs.sqlalchemy.org/en/latest/orm/extensions/automap.html#custom-relationship-arguments
    if direction is interfaces.ONETOMANY:
        kw['cascade'] = 'all, delete, delete-orphan'
        kw['passive_deletes'] = False
        kw['lazy'] = 'immediate'
    if direction is interfaces.MANYTOONE or direction is interfaces.MANYTOMANY:
        kw['viewonly'] = True

    return generate_relationship(base, direction, return_fn, attrname, local_cls, referred_cls, **kw)

删除代码是：

def cleanData():
    for partyId in partyIds:
        log("Cleaning data for {0}".format(partyId))

        invoice = Base.classes.invoice
        invoiceDelete = destSess.query(invoice).filter_by(party_id_from=partyId)
        rs = invoiceDelete.all()
        for result in rs:
            deleteChildren(result, destSess)
            destSess.delete(result)
        destSess.commit()

        voucher = Base.classes.voucher
        voucherDelete = destSess.query(voucher).filter_by(party_id=partyId)
        rs = voucherDelete.all()
        for result in rs:
            deleteChildren(result, destSess)        
            destSess.delete(result)

        destSess.commit()

def deleteChildren(result, destSess):
    for relationship in result.__mapper__.relationships:
        if relationship.direction is interfaces.ONETOMANY:
            childs = getattr(result, str(re.search(r'\.(.*)', str(relationship)).group(1)))
            for child in childs:
                if child.__mapper__.relationships:
                    deleteChildren(child, destSess)
                    destSess.commit()
                destSess.delete(child)
                destSess.commit()

解释一下，我得到了与我想从数据库中删除的派对 ID 相关的记录，并使用递归方法从我定义的关系中使用急切获取来获取孩子。如果该子记录有子记录，我将调用相同的方法。当我用完一对多关系时，我删除记录并返回其父级，同时删除该记录。

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