How to use where ActiveRecord method

The where ActiveRecord method is one of the most powerful features this ORM offers. It allows you to express your conditions as simple key-value pairs, making your code more readable & shielded from SQL injection attacks. Here’s a quick overview of how to use it:

User.where(name: "John")

The where method will return an array of matching records.

If you want to retrieve a single record you can use the first method:

User.where(name: "John").first

You can also specify multiple conditions using the and method:

User.where("name = ? and age = ?", "John", 20)

The above code will generate the following SQL:

sql
SELECT * FROM users WHERE name = 'John' AND age = 20

You can also use the or method:

User.where("name = ? or age = ?", "John", 20)

The above code will generate the following SQL:

sql
SELECT * FROM users WHERE name = 'John' OR age = 20

Specifying a Limit

You can use the limit method to specify the maximum number of records to return.

Example:

User.where(name: "John").limit(5)

This will generate the following SQL:

sql
SELECT * FROM users WHERE name = 'John' LIMIT 5

Ordering Results

You can use the order method to specify the order in which records are returned.

The order method accepts a column name & an optional direction (asc or desc).

Example:

User.where(name: "John").order("age asc")

Specifying a Default Order

If you want to specify a default order, you can use the default_scope method.

Example:

class User < ActiveRecord::Base
 default_scope { order("name asc") }
end

Specifying a Custom SQL

You can use the find_by_sql method to specify a SQL query.

Example:

User.find_by_sql("SELECT * FROM users WHERE name = 'John'")

You can also use the pluck method to specify the columns you want to retrieve.

Summary

In this article, you’ve learned how to use the ActiveRecord where limit, order and default_scope methods to manipulate the results.
This is just the tip of the iceberg. If you want to learn more about the different ways you can use where, we invite you to read the ActiveRecord where documentation.

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