ORM, or Object-Relational Mapping, is a technique that enables developers to use an object-oriented paradigm to interact with a relational database.
In simpler terms, ORM frameworks help developers interact with databases as if they were interacting with a set of objects in their programming language of choice.
Relational databases, such as MySQL or PostgreSQL, store data in tables consisting of rows and columns. Each table typically represents a specific type of entity, such as users or orders, and columns represent attributes of that entity, such as a user’s name or an order’s date.
It allows developers to create classes that represent database tables, and instances of these classes represent rows in the table. These classes can have attributes corresponding to the table’s columns and methods that allow the developer to perform data operations.
ORM frameworks provide a set of tools and methods for mapping classes and relationships to the database schema. For example, the framework can generate SQL queries to update or retrieve data or automatically create tables and columns based on class definitions.
For various programming languages, popular ORM frameworks include Django ORM for Python, Hibernate for Java, and ActiveRecord for Ruby on Rails.
Choosing the correct ORM framework for a project can be influenced by factors such as the size and complexity of the database, the programming language and framework used, and the application’s specific requirements.
Use of ORM in the Backend
ORM (Object-Relational Mapping) is a powerful tool for backend development that allows developers to interact with relational databases using an object-oriented programming paradigm. ORM frameworks are widely used in backend development to help abstract away the complexity of working with databases and make it easier to write maintainable and secure code.
Defining Models
To use ORM in backend development, developers typically define models in their code representing the database tables they want to work with. A model is a class that defines the properties of the table, such as the columns and relationships between tables.
Interacting with the Database
Developers can then interact with the database by creating instances of these models and calling methods on them, such as saving or updating data. ORM frameworks typically provide a set of tools for working with models and the database, such as functions for querying the database, handling database migrations, and managing relationships between tables.
Benefits of ORM
One of the key advantages of using ORM in backend development is that it makes it easier to write maintainable code. ORM frameworks provide a high-level abstraction that allows developers to interact with the database using their preferred programming language rather than writing low-level SQL queries. This can make the code more readable and easier to understand, reducing the risk of errors and making it easier to maintain and update over time.
Querying the Database
ORM frameworks also provide tools for querying the database, allowing developers to retrieve and manipulate data more intuitively and flexibly. For example, you could use the following code to retrieve all users with a specific email address:
This code employs the ORM framework’s “query” method to retrieve all users with the specified email address.
Another benefit of ORM is that it can make it easier to handle relationships between tables. For example, let’s say you have a database that stores information about books and authors. You could define two models for these tables
This code defines a one-to-many relationship between the Author and Book tables, where each author can have many books. The “author_id” column in the Book table is a foreign key that references the “id” column in the Author table. The “books” property in the Author model is a relationship that defines how to retrieve all the books associated with a particular author.
Using ORM, you can easily retrieve all the books associated with a particular author by calling the “books” property on the Author instance:
This code retrieves the author with an ID of 1 and then retrieves all the books associated with that author.
Handling Database Migrations
ORM frameworks can also help with database migrations, which are changes to the database schema that must be propagated across all application instances. Its frameworks typically include tools for creating and running migrations, allowing programmers to modify the database schema without writing raw SQL statements.
Security Considerations
Finally, ORM can help to reduce the risk of SQL injection attacks. ORM frameworks also typically employ parameterized queries, which allow user input to be escaped and prevent malicious code from being executed on the database.