How to do a proper upsert using sqlalchemy on postgresql?

How to do a proper upsert using sqlalchemy on postgresql?

An "upsert" operation refers to updating a row if it exists or inserting it if it doesn't exist (i.e., performing an "insert or update" operation). In PostgreSQL, this operation can be achieved using the INSERT ... ON CONFLICT ... statement. In SQLAlchemy, you can perform upserts using the insert() method along with the .on_conflict_do_update() method.

Here's how you can perform a proper upsert using SQLAlchemy on PostgreSQL:

from sqlalchemy import create_engine, text from sqlalchemy.orm import sessionmaker from sqlalchemy.ext.declarative import declarative_base from sqlalchemy import Column, Integer, String from sqlalchemy.dialects.postgresql import insert # Create a SQLAlchemy engine DATABASE_URL = "postgresql://username:password@localhost/dbname" engine = create_engine(DATABASE_URL) # Create a session Session = sessionmaker(bind=engine) session = Session() # Define a declarative base Base = declarative_base() # Define your model class Item(Base): __tablename__ = 'items' id = Column(Integer, primary_key=True) name = Column(String) # Define the values to upsert values = [ {'id': 1, 'name': 'Item 1'}, {'id': 2, 'name': 'Item 2'}, # ... ] # Create an insert statement with upsert (insert or update) logic stmt = insert(Item).values(values).on_conflict_do_update( constraint='items_pkey', # Primary key constraint name set_={'name': stmt.excluded.name} # Update the 'name' column ) # Execute the statement with engine.connect() as conn: conn.execute(stmt) # Commit the changes session.commit()

In this example:

  • Replace username, password, localhost, and dbname with your PostgreSQL connection details.
  • Define your model using SQLAlchemy's declarative syntax.
  • Create an insert statement using the insert() method and chain it with the .on_conflict_do_update() method.
  • Specify the primary key constraint name (you need to replace 'items_pkey' with your actual constraint name).
  • Specify the columns you want to update in case of a conflict using the set_ parameter.

This approach uses SQLAlchemy's powerful SQL expression language to construct the upsert statement. Keep in mind that the exact syntax may vary based on your specific use case, database schema, and version of SQLAlchemy.

Examples

  1. "SQLAlchemy upsert PostgreSQL example"

    • Description: This query aims to find examples demonstrating how to perform an upsert operation (insert or update) using SQLAlchemy with a PostgreSQL database.
    from sqlalchemy import create_engine, Column, Integer, String, MetaData, Table from sqlalchemy.dialects.postgresql import insert from sqlalchemy.orm import sessionmaker # Define database connection engine = create_engine('postgresql://username:password@localhost:5432/database') Session = sessionmaker(bind=engine) session = Session() # Define table metadata metadata = MetaData() table = Table('your_table_name', metadata, Column('id', Integer, primary_key=True), Column('name', String), Column('value', Integer)) # Prepare data for upsert data = {'id': 1, 'name': 'example', 'value': 100} # Define upsert query stmt = insert(table).values(data) stmt = stmt.on_conflict_do_update( constraint="your_table_name_pkey", set_=data ) # Execute upsert session.execute(stmt) session.commit()

  2. "SQLAlchemy PostgreSQL upsert with constraints"

    • Description: This query looks for examples demonstrating how to perform an upsert operation in SQLAlchemy while considering constraints in a PostgreSQL database.
    from sqlalchemy import create_engine, Column, Integer, String, MetaData, Table from sqlalchemy.dialects.postgresql import insert from sqlalchemy.orm import sessionmaker # Define database connection engine = create_engine('postgresql://username:password@localhost:5432/database') Session = sessionmaker(bind=engine) session = Session() # Define table metadata metadata = MetaData() table = Table('your_table_name', metadata, Column('id', Integer, primary_key=True), Column('name', String), Column('value', Integer)) # Prepare data for upsert data = {'id': 1, 'name': 'example', 'value': 100} # Define upsert query with constraints stmt = insert(table).values(data) stmt = stmt.on_conflict_do_update( constraint="your_table_name_constraint_name", set_=data ) # Execute upsert session.execute(stmt) session.commit()

  3. "SQLAlchemy upsert PostgreSQL with composite primary key"

    • Description: This query seeks examples demonstrating how to perform an upsert operation in SQLAlchemy when dealing with a PostgreSQL table having a composite primary key.
    from sqlalchemy import create_engine, Column, Integer, String, MetaData, Table from sqlalchemy.dialects.postgresql import insert from sqlalchemy.orm import sessionmaker # Define database connection engine = create_engine('postgresql://username:password@localhost:5432/database') Session = sessionmaker(bind=engine) session = Session() # Define table metadata with composite primary key metadata = MetaData() table = Table('your_table_name', metadata, Column('id1', Integer, primary_key=True), Column('id2', Integer, primary_key=True), Column('name', String), Column('value', Integer)) # Prepare data for upsert data = {'id1': 1, 'id2': 2, 'name': 'example', 'value': 100} # Define upsert query for composite primary key stmt = insert(table).values(data) stmt = stmt.on_conflict_do_update( constraint="your_table_name_pkey", set_=data ) # Execute upsert session.execute(stmt) session.commit()

  4. "SQLAlchemy upsert PostgreSQL with unique constraint"

    • Description: This query looks for examples demonstrating how to perform an upsert operation in SQLAlchemy while considering a unique constraint in a PostgreSQL table.
    from sqlalchemy import create_engine, Column, Integer, String, MetaData, Table from sqlalchemy.dialects.postgresql import insert from sqlalchemy.orm import sessionmaker # Define database connection engine = create_engine('postgresql://username:password@localhost:5432/database') Session = sessionmaker(bind=engine) session = Session() # Define table metadata with unique constraint metadata = MetaData() table = Table('your_table_name', metadata, Column('id', Integer, primary_key=True), Column('name', String, unique=True), Column('value', Integer)) # Prepare data for upsert data = {'id': 1, 'name': 'example', 'value': 100} # Define upsert query with unique constraint stmt = insert(table).values(data) stmt = stmt.on_conflict_do_update( index_elements=['name'], set_=data ) # Execute upsert session.execute(stmt) session.commit()

  5. "SQLAlchemy PostgreSQL upsert with conditional update"

    • Description: This query aims to find examples demonstrating how to perform an upsert operation in SQLAlchemy on PostgreSQL with a conditional update.
    from sqlalchemy import create_engine, Column, Integer, String, MetaData, Table from sqlalchemy.dialects.postgresql import insert from sqlalchemy.orm import sessionmaker # Define database connection engine = create_engine('postgresql://username:password@localhost:5432/database') Session = sessionmaker(bind=engine) session = Session() # Define table metadata metadata = MetaData() table = Table('your_table_name', metadata, Column('id', Integer, primary_key=True), Column('name', String), Column('value', Integer)) # Prepare data for upsert data = {'id': 1, 'name': 'example', 'value': 100} # Define upsert query with conditional update stmt = insert(table).values(data) stmt = stmt.on_conflict_do_update( index_elements=['id'], set_=data ).where( table.c.value < 100 # Conditional update ) # Execute upsert session.execute(stmt) session.commit()

  6. "SQLAlchemy upsert PostgreSQL using raw SQL"

    • Description: This query seeks examples demonstrating how to perform an upsert operation in SQLAlchemy using raw SQL statements on PostgreSQL.
    from sqlalchemy import create_engine # Define database connection engine = create_engine('postgresql://username:password@localhost:5432/database') # Prepare data for upsert data = {'id': 1, 'name': 'example', 'value': 100} # Define raw SQL upsert statement sql = """ INSERT INTO your_table_name (id, name, value) VALUES (:id, :name, :value) ON CONFLICT (id) DO UPDATE SET name = :name, value = :value; """ # Execute raw SQL upsert with engine.connect() as conn: conn.execute(sql, **data)

  7. "SQLAlchemy PostgreSQL upsert with multiple values"

    • Description: This query looks for examples demonstrating how to perform a batch upsert operation in SQLAlchemy on PostgreSQL with multiple values.
    from sqlalchemy import create_engine, Column, Integer, String, MetaData, Table from sqlalchemy.dialects.postgresql import insert from sqlalchemy.orm import sessionmaker # Define database connection engine = create_engine('postgresql://username:password@localhost:5432/database') Session = sessionmaker(bind=engine) session = Session() # Define table metadata metadata = MetaData() table = Table('your_table_name', metadata, Column('id', Integer, primary_key=True), Column('name', String), Column('value', Integer)) # Prepare data for upsert data = [ {'id': 1, 'name': 'example1', 'value': 100}, {'id': 2, 'name': 'example2', 'value': 200}, {'id': 3, 'name': 'example3', 'value': 300} ] # Define upsert query for multiple values stmt = insert(table).values(data) stmt = stmt.on_conflict_do_update( constraint="your_table_name_pkey", set_=dict([(col.name, col) for col in stmt.excluded]) ) # Execute upsert for multiple values session.execute(stmt) session.commit()

  8. "SQLAlchemy PostgreSQL upsert returning values"

    • Description: This query seeks examples demonstrating how to perform an upsert operation in SQLAlchemy on PostgreSQL and return the affected rows.
    from sqlalchemy import create_engine, Column, Integer, String, MetaData, Table from sqlalchemy.dialects.postgresql import insert from sqlalchemy.orm import sessionmaker # Define database connection engine = create_engine('postgresql://username:password@localhost:5432/database') Session = sessionmaker(bind=engine) session = Session() # Define table metadata metadata = MetaData() table = Table('your_table_name', metadata, Column('id', Integer, primary_key=True), Column('name', String), Column('value', Integer)) # Prepare data for upsert data = {'id': 1, 'name': 'example', 'value': 100} # Define upsert query with returning clause stmt = insert(table).values(data).returning(table.c.id, table.c.name, table.c.value) # Execute upsert and fetch affected rows result = session.execute(stmt) affected_rows = result.fetchall() # Print affected rows print(affected_rows)

  9. "SQLAlchemy upsert PostgreSQL using upsert() method"

    • Description: This query looks for examples demonstrating how to perform an upsert operation in SQLAlchemy on PostgreSQL using the upsert() method.
    from sqlalchemy import create_engine, Column, Integer, String, MetaData, Table from sqlalchemy.orm import sessionmaker # Define database connection engine = create_engine('postgresql://username:password@localhost:5432/database') Session = sessionmaker(bind=engine) session = Session() # Define table metadata metadata = MetaData() table = Table('your_table_name', metadata, Column('id', Integer, primary_key=True), Column('name', String), Column('value', Integer)) # Prepare data for upsert data = {'id': 1, 'name': 'example', 'value': 100} # Execute upsert using upsert() method session.merge(table, data) # Commit the transaction session.commit()

  10. "SQLAlchemy PostgreSQL upsert with subquery"

    • Description: This query aims to find examples demonstrating how to perform an upsert operation in SQLAlchemy on PostgreSQL using a subquery.
    from sqlalchemy import create_engine, Column, Integer, String, MetaData, Table from sqlalchemy.dialects.postgresql import insert from sqlalchemy.orm import sessionmaker # Define database connection engine = create_engine('postgresql://username:password@localhost:5432/database') Session = sessionmaker(bind=engine) session = Session() # Define table metadata metadata = MetaData() table = Table('your_table_name', metadata, Column('id', Integer, primary_key=True), Column('name', String), Column('value', Integer)) # Prepare data for upsert data = {'id': 1, 'name': 'example', 'value': 100} # Define subquery for upsert subquery = insert(table).values(data).on_conflict_do_update( constraint="your_table_name_pkey", set_=data ) # Execute subquery for upsert session.execute(subquery) session.commit()

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