[英]FastAPI) SQLAlchemy Foreign Key Constraint Error
检查了这 4 件事,我似乎没有发现问题:
1. Same data type
2. Same nullable designation
3. Foreign Key being assigned to PK or Unique column
4. Same Charset for both
外键:table_entity.db_id FOR Unique Column:db_entity.db_id
db_entity_schema.py(父级)
from sqlalchemy import Column, String, SMALLINT
from sqlalchemy.dialects.mysql import SMALLINT, TINYINT, BIGINT, CHAR
class DbEntity(Base=declartive_base):
__tablename__ = "db_entity"
seq = Column(BIGINT(20), primary_key=True, autoincrement=True, nullable=False)
db_id = Column(String(24), unique=True, nullable=False, comment="DB ID")
db_service_id = Column(String(24), nullable=False)
table_entity_schema.py(子)
from sqlalchemy import Column, String, ForeignKey
from sqlalchemy.dialects.mysql import SMALLINT, TINYINT, BIGINT
from sqlalchemy import UniqueConstraint
class TableEntity(Base=declartive_base):
__tablename__ = "table_entity"
__table_args__ = (UniqueConstraint("schema_name", "table_name", name="schema_table_uq_constraint"),)
table_no = Column(BIGINT(20), primary_key=True, autoincrement=True, nullable=False)
db_id = Column(String(24), ForeignKey("db_entity.db_id"), nullable=False, comment="DB ID")
db_service_id = Column(String(24), nullable=False)
schema_name = Column(String(128), nullable=False)
table_name = Column(String(128), nullable=False)
迁移的时候,导致errno: 150 "Foreign key constraint is incorrectly formed"
比较费解。
您是否尝试过声明相关对象
from sqlalchemy import Column, String, ForeignKey
from sqlalchemy.dialects.mysql import SMALLINT, TINYINT, BIGINT
from sqlalchemy import UniqueConstraint
class TableEntity(Base=declartive_base):
__tablename__ = "table_entity"
__table_args__ = (UniqueConstraint("schema_name", "table_name", name="schema_table_uq_constraint"),)
table_no = Column(BIGINT(20), primary_key=True, autoincrement=True, nullable=False)
db_id = Column(String(24), ForeignKey(DbEntity.db_id), nullable=False, comment="DB ID")
db_service_id = Column(String(24), nullable=False)
schema_name = Column(String(128), nullable=False)
table_name = Column(String(128), nullable=False)
话虽如此,您似乎在 DbEntity.seq 上有一个非常好的主键,为什么不将它用作您的外键呢?
这可能不是完整的答案,但我发布这个是为了显示我自动生成的迁移,看看它是否有助于缩小问题的范围。
使用SQLAlchemy 1.4.45 、 alembic 1.9.0 、 pymysql 1.0.2和mysql 8.0.31-1.el8 (码头图像)。
我不太了解 mysql 驱动程序,所以我没有偏好。
"""empty message
Revision ID: 771ce744af5d
Revises:
Create Date: 2022-12-22 02:11:08.325864
"""
from alembic import op
import sqlalchemy as sa
from sqlalchemy.dialects import mysql
# revision identifiers, used by Alembic.
revision = '771ce744af5d'
down_revision = None
branch_labels = None
depends_on = None
def upgrade() -> None:
# ### commands auto generated by Alembic - please adjust! ###
op.create_table('db_entity',
sa.Column('seq', mysql.BIGINT(display_width=20), autoincrement=True, nullable=False),
sa.Column('db_id', sa.String(length=24), nullable=False, comment='DB ID'),
sa.Column('db_service_id', sa.String(length=24), nullable=False),
sa.PrimaryKeyConstraint('seq'),
sa.UniqueConstraint('db_id'),
schema='testdb'
)
op.create_table('table_entity',
sa.Column('table_no', mysql.BIGINT(display_width=20), autoincrement=True, nullable=False),
sa.Column('db_id', sa.String(length=24), nullable=False, comment='DB ID'),
sa.Column('db_service_id', sa.String(length=24), nullable=False),
sa.Column('schema_name', sa.String(length=128), nullable=False),
sa.Column('table_name', sa.String(length=128), nullable=False),
sa.ForeignKeyConstraint(['db_id'], ['testdb.db_entity.db_id'], ),
sa.PrimaryKeyConstraint('table_no'),
sa.UniqueConstraint('schema_name', 'table_name', name='schema_table_uq_constraint'),
schema='testdb'
)
# ### end Alembic commands ###
def downgrade() -> None:
# ### commands auto generated by Alembic - please adjust! ###
op.drop_table('table_entity', schema='testdb')
op.drop_table('db_entity', schema='testdb')
# ### end Alembic commands ###
我只是把它放在一起以自动生成一个修订版,所以请原谅它的格式和混乱的导入。
from logging.config import fileConfig
from sqlalchemy import engine_from_config
from sqlalchemy import pool
from alembic import context
# this is the Alembic Config object, which provides
# access to the values within the .ini file in use.
config = context.config
# Interpret the config file for Python logging.
# This line sets up loggers basically.
if config.config_file_name is not None:
fileConfig(config.config_file_name)
from sqlalchemy import (
Integer,
String,
ForeignKey,
UniqueConstraint,
)
from sqlalchemy.schema import (
Column,
)
from sqlalchemy.orm import backref, relationship, declarative_base, Session
from sqlalchemy import create_engine, MetaData, Column, ForeignKey, Integer, String
Base = declarative_base(metadata=MetaData(schema="testdb"))
from sqlalchemy import Column, String, SMALLINT
from sqlalchemy.dialects.mysql import SMALLINT, TINYINT, BIGINT, CHAR
class DbEntity(Base):
__tablename__ = "db_entity"
seq = Column(BIGINT(20), primary_key=True, autoincrement=True, nullable=False)
db_id = Column(String(24), unique=True, nullable=False, comment="DB ID")
db_service_id = Column(String(24), nullable=False)
class TableEntity(Base):
__tablename__ = "table_entity"
__table_args__ = (UniqueConstraint("schema_name", "table_name", name="schema_table_uq_constraint"),)
table_no = Column(BIGINT(20), primary_key=True, autoincrement=True, nullable=False)
db_id = Column(String(24), ForeignKey("db_entity.db_id"), nullable=False, comment="DB ID")
db_service_id = Column(String(24), nullable=False)
schema_name = Column(String(128), nullable=False)
table_name = Column(String(128), nullable=False)
# add your model's MetaData object here
# for 'autogenerate' support
# from myapp import mymodel
# target_metadata = mymodel.Base.metadata
target_metadata = Base.metadata
# other values from the config, defined by the needs of env.py,
# can be acquired:
# my_important_option = config.get_main_option("my_important_option")
# ... etc.
def run_migrations_offline() -> None:
"""Run migrations in 'offline' mode.
This configures the context with just a URL
and not an Engine, though an Engine is acceptable
here as well. By skipping the Engine creation
we don't even need a DBAPI to be available.
Calls to context.execute() here emit the given string to the
script output.
"""
url = config.get_main_option("sqlalchemy.url")
context.configure(
url=url,
target_metadata=target_metadata,
literal_binds=True,
dialect_opts={"paramstyle": "named"},
)
with context.begin_transaction():
context.run_migrations()
def run_migrations_online() -> None:
"""Run migrations in 'online' mode.
In this scenario we need to create an Engine
and associate a connection with the context.
"""
connectable = engine_from_config(
config.get_section(config.config_ini_section),
prefix="sqlalchemy.",
poolclass=pool.NullPool,
)
with connectable.connect() as connection:
context.configure(
connection=connection, target_metadata=target_metadata
)
with context.begin_transaction():
context.run_migrations()
if context.is_offline_mode():
run_migrations_offline()
else:
run_migrations_online()
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