How to Display Actual SQL Queries in SQLAlchemy?

Printing Actual SQL Queries in SQLAlchemy

In SQLAlchemy, it is crucial to understand how to display the raw SQL that corresponds to your database operations. This is essential for troubleshooting, debugging, and optimizing your application's database communication.

General Approach

In most cases, you can easily view the SQL string representation of a statement or query with:

<code class="python">print(str(statement))</code>

This applies both to ORM Queries and raw select() expressions.

Compiling to a Specific Dialect

If you need to view the SQL compiled for a specific dialect or engine, you can use the compile() method:

<code class="python">print(statement.compile(someengine))</code>

or without an engine:

<code class="python">from sqlalchemy.dialects import postgresql
print(statement.compile(dialect=postgresql.dialect()))</code>

Inlining Bound Parameters

Default behavior in SQLAlchemy is to use bind parameters in SQL strings, ensuring security by preventing SQL injection attacks. To bypass bound parameters and inline actual values, use the literal_binds flag in compile_kwargs:

<code class="python">print(s.compile(compile_kwargs={"literal_binds": True}))</code>

For custom types not supported by this approach, implement a TypeDecorator with a process_literal_param method to ensure inline rendering:

<code class="python">class MyFancyType(TypeDecorator):
    def process_literal_param(self, value, dialect):
        return "my_fancy_formatting(%s)" % value

print(
    tab.select().where(tab.c.x > 5).compile(
        compile_kwargs={"literal_binds": True})
)</code>

The above is the detailed content of How to Display Actual SQL Queries in SQLAlchemy?. For more information, please follow other related articles on the PHP Chinese website!