flask – Sqlalchemy – 当数据有关系时,如何正确地将数据批量插入数据库

2023年6月18日 264次阅读

我有一系列事物的数据文件.每件东西都有一个基因列在其中.这是一个多关系,因为每个基因都可以是多个事物的一部分,但每个事物只能有一个基因.

想象一下这些模型大致如下：

class Gene(db.Model):

    __tablename__ = "gene"

    id          = db.Column(db.Integer, primary_key=True)

    name1   = db.Column(db.Integer, index=True, unique=True, nullable=False)  # nullable might be not right
    name2   = db.Column(db.String(120), index=True, unique=True)

    things = db.relationship("Thing", back_populates='gene')

    def __init__(self, name1, name2=None):
        self.name1 = name1
        self.name2 = name2

    @classmethod
    def find_or_create(cls, name1, name2=None):
        record = cls.query.filter_by(name1=name1).first()
        if record != None:
            if record.name2 == None and name2 != None:
                record.name2 = name2
        else:
            record = cls(name1, name2)
            db.session.add(record)
        return record


class Thing(db.Model):

    __tablename__ = "thing"

    id          = db.Column(db.Integer, primary_key=True)

    gene_id     = db.Column(db.Integer, db.ForeignKey("gene.id"), nullable=False, index=True)
    gene        = db.relationship("Gene", back_populates='thing')

    data    = db.Column(db.Integer)

我想批量插入很多东西,但我害怕通过使用

    db.engine.execute(Thing.__table__.insert(), things)

我不会在数据库中拥有关系.是否有某种方法可以保留与批量添加的关系,或以某种方式顺序添加这些关系,然后在以后建立关系？所有the documentation about bulk adding似乎都假设您想要插入非常简单的模型,并且当您的模型更复杂时(例如上面的示例是一个愚蠢的版本),我有点迷失方向.

– 更新1 –

This answer似乎表明没有真正的解决方案.

This answer似乎证实了这一点.

最佳答案 我实际上改变了我的代码,我认为现在更好,所以我也改变了我的答案.

我定义了以下2个表.集合和数据,对于集合中的每个集合,数据中有许多数据.

class Sets(sa_dec_base):
    __tablename__ = 'Sets'
    id = sa.Column(sa.Integer, primary_key=True)
    FileName = sa.Column(sa.String(250), nullable=False)
    Channel = sa.Column(sa.Integer, nullable=False)
    Loop = sa.Column(sa.Integer, nullable=False)
    Frequencies = sa.Column(sa.Integer, nullable=False)
    Date = sa.Column(sa.String(250), nullable=False)
    Time = sa.Column(sa.String(250), nullable=False)
    Instrument = sa.Column(sa.String(250), nullable=False)
    Set_Data = sa_orm.relationship('Data')
    Set_RTD_spectra = sa_orm.relationship('RTD_spectra')
    Set_RTD_info = sa.orm.relationship('RTD_info')
    __table_args__ = (sa.UniqueConstraint('FileName', 'Channel', 'Loop'),)
class Data(sa_dec_base):
    __tablename__ = 'Data'
    id = sa.Column(sa.Integer, primary_key = True)
    Frequency = sa.Column(sa.Float, nullable=False)
    Magnitude = sa.Column(sa.Float, nullable=False)
    Phase = sa.Column(sa.Float, nullable=False)
    Set_ID = sa.Column(sa.Integer, sa.ForeignKey('Sets.id'))
    Data_Set = sa_orm.relationship('Sets', foreign_keys = [Set_ID])

然后,我将此函数写入bulk_insert数据与关系.

def insert_set_data(session, set2insert, data2insert, Data):
""" 
Insert set and related data; with uniqueconstraint check on the set
set2insert is the prepared set object without id. A correct and unique id will given by the db itself 
data2insert is a big pandas df, so that bulk_insert is used
"""

session.add(set2insert)
try:
    session.flush()
except sa.exc.IntegrityError as err: # here catch uniqueconstraint error if set already in db
    session.rollback()
    print('already inserted ', set2insert.FileName, 'loop ', set2insert.Loop, 'channel ', set2insert.Channel)
    pass
else: # if not error, flush will give the id to the set ("Set.id")
    data2insert['Set_ID'] = set2insert.id # pass Set.id to data2insert as foreign_keys to keep relationship
    data2insert = data2insert.to_dict(orient = 'records') # convert df to record for bulk_insert
    session.bulk_insert_mappings(Data, data2insert) # bulk_insert
    session.commit() # commit only once, so that it is done only if set and data were correctly inserted
    print('inserting ', set2insert.FileName, 'loop ', set2insert.Loop, 'channel ', set2insert.Channel)

无论如何,可能还有其他更好的解决方案.

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