How to Fetch Data from One Table Based on Another Table's ID Using FastAPI and SQLAlchemy

Learn how to easily retrieve data from one table based on another table's ID in FastAPI using SQLAlchemy without resorting to raw SQL queries.
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Introduction

When working with relational databases, it's common to have scenarios where you need to fetch data from one table based on the IDs of another table. If you're using FastAPI with SQLAlchemy, achieving this task becomes quite straightforward. In this post, we'll explore how to compare IDs from two tables and retrieve specific details, enhancing the process of working with databases in Python.

The Problem

Let's assume you have two tables:

Table1 which contains an id column.

Table2 which has an id, server, port, and endpoint columns.

Your objective is to compare the id fields from both tables and, when they match, fetch the server, port, and endpoint values from Table2. Importantly, you prefer not to use raw SQL queries but rather stick with ORM (Object-Relational Mapping) style queries provided by SQLAlchemy.

Setting Up Your Models

Before diving into the solution, let’s take a closer look at how to define your models using SQLAlchemy.

Model Definition

Here’s how your models should look for Table1 and Table2:

[[See Video to Reveal this Text or Code Snippet]]

Inserting Sample Data

To test our operations, we can insert some sample rows:

[[See Video to Reveal this Text or Code Snippet]]

Fetching the Data

Now that we have our models set up and data populated, we can proceed with the query to fetch the required information.

Querying with SQLAlchemy ORM

To retrieve the server, port, and endpoint based on matching id values from both tables, you can use the following query:

[[See Video to Reveal this Text or Code Snippet]]

Breakdown of the Query:

.all() fetches all results that satisfy the given condition.

Output

When you run this code, you should see results like:

[[See Video to Reveal this Text or Code Snippet]]

These results indicate that the records from Table2 where the id matches an id from Table1 have been successfully retrieved.

Conclusion

Fetching data from one table based on another table's ID using FastAPI and SQLAlchemy is a powerful feature that allows for efficient database querying while maintaining code simplicity and readability. This approach using ORM enables developers to avoid raw SQL, making their applications cleaner and easier to maintain.

By following the steps outlined above, you can efficiently perform relational data fetching in your applications. Happy coding!